# Using full frame lens on crop body cameras ?



## striperone (Dec 13, 2014)

From the video I've posted below, it looks as though it's a (big) waste of money to purchase high rent full frame glass for a crop body including the all new 7D mark II. 
I'm disappointed with this as it "was" my intention. 
So, I hope someone will clarify this for me but it seems that with the new 7D mark II will actually produce better results/sharper images with a cheaper lens that is made for a crop body? To my knowledge, Canon doesn't produce any high quality glass for their crop sensor cameras?

I wanted the 7D mark II with a Canon EF 70-200mm f/2.8L IS II USM Lens. If what I'm seeing in the video below is correct and I sure would assume so, that this combination is a total waste of money.

Perhaps I should wait to see if Canon is soon to release a new version of the 5D mark III?

https://www.youtube.com/watch?v=YDbUIfB5YUc&list=PLBE338967F8DB7F2A


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## wickidwombat (Dec 13, 2014)

hahaha 

as soon as i clicked the link and saw who it was i closed it

without even watching the video i can say its not worth the time wasted
the guy is an unmitigated ass clown

basically using full frame lenses on crop bodies work just fine

essentially you are "wasting" the outer part of the image circle which usually is not as sharp as the center
if you look at any lens mtf chart you will see the line drops off towards the right edge of the chart
basically with these charts the higher and flatter the line the better the optics and for crop vs full frame you truncate the graph at the line that represents crop instead of reading it all the way to the right

then there is the AF performance of f2.8 and faster lenses with canons high end af systems like the 5d3 1dx and 7d2 which perform better than slower lenses 

so in summary a great lens like the 70-200 f2.8 is still a fantastic lens on crop (i regularly use my 135 f2L on my eos M and its AF is great even on that camera)

be cautious about listening too much to these youtube vlog clowns that really struggle in the Intellect department.


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## striperone (Dec 14, 2014)

I hear ya' wickidwombat and can appreciate your thoughts on the utubes, and surely your rite in that you can't believe everything that everyone says. I also appreciate your reply.
I know you don't care for the guy in the video but take another minute and watch it starting at "2:40" this is where he talks about it with numbers. After you see that, tell me what you think. I have been told by others to dismiss it as well. Just looking for reassurance by people that are far more knowledgeable then I, cause I can't afford to pull the trigger on the purchase only to wish I had bought something else.

I want the best possible images I can get shooting motorsports mainly panning. My budget would allow the new 7D mark II or I can push it to the 5D mark III with the cannon EF 70-200mm f/2.8L IS II USM Lens. It's a hard decision because it can only be one of the camera bodies. 

I currently have a T3i with a canon 75-300 zoom. Anything at this point will be an improvement.


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## lintoni (Dec 14, 2014)

+1 to wickidwombat's comments.

Search "Tony Northrup" on this site and you'll find a few thmreads of people laughing at his pronouncements.

Lens - have you considered the new 100-400, or do you find you're using your 75-300 most often at 200 and below?


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## neuroanatomist (Dec 14, 2014)

wickidwombat said:



> hahaha
> 
> as soon as i clicked the link and saw who it was i closed it
> 
> ...



I didn't click the link, but judging by your comments I'm going to hazard a guess...Tony Northrup? He's the guy that's smart enough to have said that the D810 is the best camera, but the 5DIII is probably ok if your not a pro and you just post your pics to Facebook. So if that makes sense to someone, they should by all means take his words as Truth with a capital 'T'. 

:


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## striperone (Dec 14, 2014)

lintoni, I rarely push that lens out beyond say 150. Only to catch some action/accident etc. Anything beyond that and the image is quite shabby, even after extensive editing. I did see where they had released the lens your referring to and could use it now and then, but the 75-200 would probably be the 'go to' lens more often then not. 
I also did a quick search on tony northrup and now see what you guys mean...


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## dcm (Dec 14, 2014)

It's no waste, particularly if you might get a FF body down the road. Glass lasts a long time, bodies change faster. I never used the kit lens on my T2i or purchased any EF-S lenses for it. I purchased L glass to go with it and and kept adding to the collection. The 24-105L was my first L and it got a lot of use. Three years later I purchased a 6D. Some lenses that are soft around the edge might even benefit from a crop sensor ;-)

I later decided to go the M route for my crop sensor and added some EF-M lenses for it. I occasionally mount some L glass on it.


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## neuroanatomist (Dec 14, 2014)

striperone said:


> I know you don't care for the guy in the video but take another minute and watch it starting at "2:40" this is where he talks about it with numbers. After you see that, tell me what you think.



Well, I swore his D810 infomercial would be the first, last, and only Northrup video I watched. But, in general the higher-end EF-S lenses are often optically better than EF and/or L lenses on the same crop body. The 17-55/2.8 is better than the 24-105L, the 10-22mm is better than the 17-40L, to give a couple of examples. The 70-200/2.8L IS II is one of the best zooms available, but in fact the EF-S 55-250 STM comes close when stopped down to f/8. A lot of what you're paying for with the expensive L lenses is the (usually) fast and constant aperture and a lens that's nearly as sharp wide open as stopped down to f/8. 

So, a 7DII with a 55-250 STM comes pretty close to a 7DII with a 70-200/2.8L IS II. But...put that 70-200 II on a 5DIII and the IQ will soundly trump the same lens on the 7DII. 




striperone said:


> I want the best possible images I can get shooting motorsports mainly panning. My budget would allow the new 7D mark II or I can push it to the 5D mark III with the cannon EF 70-200mm f/2.8L IS II USM Lens. It's a hard decision because it can only be one of the camera bodies.



If 200mm on FF (same as 125mm on your T3i is long enough, the 5DIII + 70-200 II will deliver much better image quality. If you need more focal length, the 70-300/4-5.6L or new 100-400 II on the 5DIII would still surpass the 70-200 II on the 7DII.


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## Mt Spokane Photography (Dec 14, 2014)

I think that you generally are paying more than needed when buying a FF lens for a crop. However, for long telephoto lenses, 300mm or over, that's not the case. If you don't intend to go to FF, and a good crop lens exists, then there is no need to pay extra for a FF lens that is little if any better.

I'd certainly take a 17-55mm IS over the 17-40L for use on a crop. My 24-105mmL was great on my 40D and then 7D, but it did not go wide enough for many photos. My 70-200mm f/4 IS was surpurb on my 7D as well. 

I'd also be inclined to go for the 16-35mm f/4 on a crop, but my 15-85mm EF-s was a very good walk around lens. I finally sold it, several months after selling my last crop body and buying a 2nd FF body.


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## timmy_650 (Dec 14, 2014)

awhile ago I rented 70-200 2.8ii for my t2i and the pictures were amazing. I wouldnt call it a waste of money. I thought about getting that lens but I decide to use my money on a 6D and got a 70-200 f4 which fit my needs better. On the other hand I had got Tamron 17-35 2.8 lens when I still had my t2i which was kinda a "waste" of money I could of got something better for me money but I knew I wanted to go full frame, so it was nice to have when i got the 6D. So it also matter where you want to end up with your camera gear.


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## wickidwombat (Dec 14, 2014)

neuroanatomist said:


> So, a 7DII with a 55-250 STM comes pretty close to a 7DII with a 70-200/2.8L IS II. But...put that 70-200 II on a 5DIII and the IQ will soundly trump the same lens on the 7DII.



and thats not even accounting for the massive AF performance differential between the 2 lenses and the 2 extra stops of light, panning mode IS on the 70-200 f2.8 ....


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## wickidwombat (Dec 14, 2014)

if I was looking at getting a new 7D II and didnt have many lenses

I would get the following lenses
new 10-18mm IS canon STM
sigma 18-35 f1.8
sigma 50mm art
canon 70-200 f2.8 IS mkII

as it is i have the eos-M and 11-22 IS which i use ALOT because the package is so small (really hope the next M gets the 7D2 sensor)

i use the 50 art mostly on my 5Dmk3 and usually carry around the 135f2L if i like something longer
I use the 70-200 alot less since getting the 135 however there are many situations the flexability of the zoom trumps the speed and sweetness of the 135 f2L

I also bet the 135 f2L would be a stunningly good lens on the 7Dmk2 although i've never tried it YET!


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## FTb-n (Dec 14, 2014)

The video is nuts!

By Northrup's logic, my EF-S 18-135 should be sharper than my EF 70-200 f2.8L II within the same focal range. But, it just isn't so. By his math, the same 70-200 on a 7D should be sharper than on a 5D3 after cropping the image in post. But, this isn't so. I've done my own real world tests. Those 8 full frame megapixels can produce sharper images than those 18-20 crop body megapixels. (The 7D2 only has 20 MP, not 24.) Northrup fails consider the fact that larger full frame and smaller crop sensor pixels are different.

As for your dilemma, unless you shoot fast action in plenty of light, I can highly recommend the 5D3 with the 70-200 f2.8L II. The full frame body will give you greater control of DOF (because f2.8 yields a smaller DOF), better performance in low light, and more color depth. I also think that the focal range is more useful on full frame for events and indoor sports.

However, this lens is a great lens on crop. It was my most used lens by far with my 7D -- far sharper than my non-L tele-zooms. Based on reviews, the 7D2 would also be a fine choice.

There is one area in which I do agree with Northrup. The 24-70 2.8 II may not be the best choice for crop, only because the 17-55 f2.8 is such an exceptional lens. It likely offers a more useful focal range, plus it has IS. However, while I haven't done head-to-head tests, I would expect the 24-70 2.8 II to be sharper than the 17-55. When I use my 7D and need a short zoom, I still grab the 17-55 and would recommend it for the IS and wider focal length. As long as you understand the limitations of each lens and they won't hinder your need, then either lens will be just fine on crop.

For what it's worth, before going full frame, my goto kit was a 60D/17-25 f2.8 and 7D/70-200 f2.8L II.


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## sunnyVan (Dec 14, 2014)

striperone said:


> From the video I've posted below, it looks as though it's a (big) waste of money to purchase high rent full frame glass for a crop body including the all new 7D mark II.
> I'm disappointed with this as it "was" my intention.
> So, I hope someone will clarify this for me but it seems that with the new 7D mark II will actually produce better results/sharper images with a cheaper lens that is made for a crop body? To my knowledge, Canon doesn't produce any high quality glass for their crop sensor cameras?
> 
> ...



I didnt watch the video. I'm no expert but I will share my unbiased view. Full frame lenses are very difficult to design and expensive to produce. It's difficult because full frame area is so large and it's hard to make the corners as sharp as the central area. With a cropped sensor and a full frame lens, only the area towards the center is being used (maybe 80%?), so the corners are not being used, in a way wasted. However, there are not that many high quality efs lenses ( although the ones coming out seem pretty good). They cost less to produce and are cheaper for us consumers. Some people (most of us on this forum) get picky over time and move on to full frame bodies. It's wise to have full frame lenses to begin with because they should serve you well for many many years. Even though you don't use the corners now, down the road when you upgrade you will need ff lenses. They are better constructed and generally hold value well. But it all depends on your needs. I know I need full frame because I need high iso performance for indoor use. You may have different needs and may be happy with a cropped sensor. 7D mk2 is a great camera but it's not suitable for everyone. I don't your needs. You have to figure it out. Using full frame lenses on cropped body is not necessarily a waste of money. It depends. Just remember that ef lenses can fit all canon cameras and efs is dedicated to cropped body. Once I realized that fact I stopped investing in efs. On the other hand, efs lenses are typically cheaper and lighter. Again, for uncompromising image quality you will need full frame sensor and lenses eventually.


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## timmy_650 (Dec 14, 2014)

It isn't all about the sharpness and that whole part about 7mp ect. Some of my wife's favorite pictures came from my 1D which has 4 mp, so in the dxo mark numbers it is crap. But they are still hanging on my wall in 8x10 and look great.


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## TeT (Dec 14, 2014)

just regarding image quality: (there are other things that make an L lens an L lens)

studying comparison image quality charts just using the center & middle areas.. many of the EF S lenses compare nicely to the highest quality L lenses. 55 250 v 70 200 II (especially in optical light conditions) performs a lot closer than you would probably guess. 

many non EF S lenses improve with use on a crop sensor just by benefit of losing their worst attribute, corners. You dont have to avoid the edges for important image components wide open when used on a crop body.


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## 9VIII (Dec 14, 2014)

If you're going for sports or even medium paced action I wouldn't hesitate to get the 70-200ISII and 7DII, even if sharpness isn't optimal you aren't going to get blazing fast AF on an EF-S lens.
So that's a resounding NO as far as whether or not crop specific lenses are better than full frame lenses in that application.

If you're more into landscapes and slower paced shots I would put the money into a full frame body rather than a nice lens, a used 5D2 and the Pancake is an amazing combo (actually with prices on the 6D lately that's probably your best bet).
The 7D2 is going to be a favourite in many applications for a long time to come though, it can't hurt to have a machine gun even if you only need a pistol.


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## Hjalmarg1 (Dec 14, 2014)

striperone said:


> From the video I've posted below, it looks as though it's a (big) waste of money to purchase high rent full frame glass for a crop body including the all new 7D mark II.
> I'm disappointed with this as it "was" my intention.
> So, I hope someone will clarify this for me but it seems that with the new 7D mark II will actually produce better results/sharper images with a cheaper lens that is made for a crop body? To my knowledge, Canon doesn't produce any high quality glass for their crop sensor cameras?
> 
> ...


DxO produce very detailed scores for various FF lenses mounted on APS-C Cameras and they do NOT consider a waste of money. One example is the 7D2+400mm/5.6L combo which is one of the best for birding.


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## Don Haines (Dec 14, 2014)

A better quality lens is a better quality lens. Period.

If you use it on FF or if you use it on a crop body, it will produce higher image quality than an inferior lens. Period.

A 200F2.8 lens designed for a FF camera will have the same size big element as a 200F2.8 lens designed for a crop camera. The only differences would be that the internal elements would be slightly smaller.... but not very much so. The optical design for the two cameras would be VERY close... if not identical..... 

To design an EFS lens to be smaller than it's FF counterpart, you have to change the optical design so that the last element group bends the light more sharply than the FF counterpart. Sharper bends are bad! They are much harder to do well and all things being equal, you get an inferior lens. Plus, the light hitting your sensor is at a greater angle than with FF lenses... this can mean photons not hitting the active part of the sensor and that means less light.

A FF lens should outperform a crop lens when used on a crop camera.


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## Don Haines (Dec 14, 2014)

Take a 200mm lens with a 72mm large element. The F value is 200/72, or F2.8.

Take that lens and move it to a crop body.... it is still a 200mm lens with a 72mm large element.... it is still a F2.8 lens. There is no Harry Potter magic going on here... the length of the lens and the size of the elements do not magically change.... it is a 200F2.8 lens period! 

None of the optical properties of the lens are going to change. PERIOD!!!!!!!

Imagine two cameras built with the same level of technology.
Camera 1 is a 20Mpixel crop camera. Camera 2 is a 50Mpixel FF camera. The pixels on the sensor are the exact same size.... they are identical. Take a picture with the two cameras and the central part of the FF image will be indistinguishable from the crop image. They will have the same brightness.... they will have the same depth of field.... they will have the same sharpness.


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## neuroanatomist (Dec 14, 2014)

Don Haines said:


> A FF lens _should_ outperform a crop lens when used on a crop camera.



Except when it doesn't. The EF-S 17-55/2.8 IS delivers better IQ than the 24-105L or 17-40L, plus it's a stop faster. The 17-55 beats the 16-35 II as well as having IS and being half the cost. 

In the ultrawide to normal focal ranges, the smaller image circle makes optical design easier. That, in turn, leads to the potential for either lenses cheaper than 'comparable' EF lenses, or lenses similar in price but with better performance. As your examples highlight, in the telephoto range all that changes.


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## Berowne (Dec 14, 2014)

The new Crop-Lenses from Canon are really nice. The EF-S 18-55 STM is a bargain. You need no EF 16-35 on APS-C for more than 1000€, its simply not necessary. 

Is there anybody who will use Mediumformat-Lenses on 35mm-Fullframe? Will you use Cine-Lenses on DSLR - they are really expensive, they mus be a lot better! 

Greetings Andy


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## TexPhoto (Dec 14, 2014)

*Tony Northrop, any of these guys get way more hits when they take a controversial opinion.* FF lenses work great with crop cameras. For longer lenses, your only choice is FF lenses. 

Tony Northrop, has said again and again, his favorite wildlife combo is the 7d (now the 7DII) and the 400mm f5.6 (a FF lens!)


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## Ryan85 (Dec 14, 2014)

TexPhoto said:


> *Tony Northrop, any of these guys get way more hits when they take a controversial opinion.* FF lenses work great with crop cameras. For longer lenses, your only choice is FF lenses.
> 
> Tony Northrop, has said again and again, his favorite wildlife combo is the 7d (now the 7DII) and the 400mm f5.6 (a FF lens!)



+1 Absoluty


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## Harv (Dec 14, 2014)

I watch Tony Northrup vidoes for only one reason..... entertainment. They are always good for a laugh. ;D


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## RunAndGun (Dec 14, 2014)

Berowne said:


> The new Crop-Lenses from Canon are really nice. The EF-S 18-55 STM is a bargain. You need no EF 16-35 on APS-C for more than 1000€, its simply not necessary.
> 
> Is there anybody who will use Mediumformat-Lenses on 35mm-Fullframe? *Will you use Cine-Lenses on DSLR* - they are really expensive, they mus be a lot better!
> 
> Greetings Andy



I have… But you better use Live View to focus, because it's a Mother to try through the optical VF.  8)

On a side note, if they would get rid of the mirror and OVF (like on mirrorless) and put high quality EVF's(like we have on the TV side), like an OLED which use very small panels, but high magnification, manual focus becomes a very viable option, again.


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## Ryan85 (Dec 14, 2014)

GraFax said:


> While I understand that many people find Northrup's mannerisms annoying, I think it's a mistake to dismiss the notion that some of Canon's best performing EF lenses may not perform especially well on cameras with smaller image circles. I've spent a few minutes checking the relative performance of some of my lenses in DXO's database and I have to admit I've been surprised by what I've found. There does seem to be some merit in the idea that len's designed for the smaller image circle outperform the more expensive L's. No need to take my, or Northrup's, word for it. You can look for yourself if you're interested.



+1


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## Don Haines (Dec 14, 2014)

neuroanatomist said:


> Don Haines said:
> 
> 
> > A FF lens _should_ outperform a crop lens when used on a crop camera.
> ...


+1

There are some lenses that Canon really got right when designing..... like the series 2 big whites.. but for zoom lenses you have to love the 70-200's for FF and the 17-55 for crops.... both examples of superb design that would be very hard to improve on.... and both are within the 3X zoom range limit. It is very hard to do a decent zoom with 4X or more zoom... too much compromise in the design...


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## benperrin (Dec 14, 2014)

I really don't get the hatred towards Tony Northrup. He makes good videos in my opinion and tries to be as unbiased as possible. He publicly admits when he's wrong. He's also quite level headed and the constant victim of internet trolls. He's just a camera geek doing what he loves doing. The funny thing is I never see people having a go at Kelby or Polin who just talk crap for 99% of their videos. Yes, I don't trust Dxomark either and think that their data doesn't represent reality, but can we stop bashing Northrup for a moment.


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## wickidwombat (Dec 14, 2014)

benperrin said:


> I really don't get the hatred towards Tony Northrup. He makes good videos in my opinion and tries to be as unbiased as possible. He publicly admits when he's wrong. He's also quite level headed and the constant victim of internet trolls. He's just a camera geek doing what he loves doing. The funny thing is I never see people having a go at Kelby or Polin who just talk crap for 99% of their videos. Yes, I don't trust Dxomark either and think that their data doesn't represent reality, but can we stop bashing Northrup for a moment.


Don't even get me started on polin....
You tube is full of these clowns .... Northrup is particularly bad because he blatantly presents rubbish as fact which causes people who are trying to learn confusion and really he just talks crap for such a long time analysing numbers charts and spec sheets. Oh joy x manufacturer releases a specs sheet for new camera y immediately Northrup will trot out and hour long drivel fest going over the specs like he actually knows what he is talking about then he will proceed to making sweeping assessments as to good the camera is based on this rubbish.

Trouble is he believes his own press.


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## Ryan85 (Dec 14, 2014)

benperrin said:


> I really don't get the hatred towards Tony Northrup. He makes good videos in my opinion and tries to be as unbiased as possible. He publicly admits when he's wrong. He's also quite level headed and the constant victim of internet trolls. He's just a camera geek doing what he loves doing. The funny thing is I never see people having a go at Kelby or Polin who just talk crap for 99% of their videos. Yes, I don't trust Dxomark either and think that their data doesn't represent reality, but can we stop bashing Northrup for a moment.



+1. Ive only seen a handful of his videos and don't agree with everything he says and some of his test and stamens can be a little goofy. But I don't get the bashing of him about everything.


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## Joey (Dec 14, 2014)

Watched the early part of Tony Northrup's video until he asserts that a 24-70mm f/2.8 lens on a 1.5x crop body behaves 'exactly like' a 36-105mm f/4.2 lens on a full frame body - and follows that up by explaining 'you don't get either the depth of field, the total light gathered, or the angle of view you have to change all of those things'.

No, Tony, a 24-70mm f/2.8 lens on a 1.5x crop body behaves like a 26-105mm f/2.8 lens on a full frame body. It's an f/2.8 lens and that doesn't change. The light gathering that's relevant here is the light gathered per unit sensor area - and each unit of sensor area on the crop body is getting the same amount of light through the lens as each unit of sensor area on the full frame body. The crop reduces the field of view and has an effect on the depth of field if you change your camera position or (if it's a zoom lens) the focal length to give the same field of view.

So, ignoring Tony Northrup, to address your question (as others have done very fully):

It is not true that Canon have not produced any high quality EF-S glass - they just haven't produced any that they've designated 'L'. Several of the EF-S lenses are optically very very good, such as the 60mm macro which is optically comparable to the 100mm f/2.8L EF lens, also the 17-55mm f/2.8, and both the 10-22mm and 10-18mm ultrawide lenses are remarkably good. That they approach the optical quality of Canon's 'L' EF lenses does not indicate that 'L' lenses are wasted on crop bodies, rather that some of the EF-S lenses are very very good. 

It has always been true that the optical design of wide angle lenses for SLR bodies is difficult. A 24mm lens has an optical centre only 24mm from the focal plane and that doesn't leave enough room for a mirror between the lens and sensor so additional elements must be used to push the focus point further away from the rear of the lens, and also requires the outer elements to be larger. It's called retrofocal design. The EF-S lenses can be designed to protrude slightly into the lens throat because the mirror on a crop body is smaller than on a full frame body. So simpler designs and smaller lens elements may produce similar (or perhaps even better) optical quality as the expensive complex lenses designed for full frame. Retrofocal design is unnecessary for longer focal lengths so there's no reason to produce EF-S telephoto lenses.

Current crop sensors have VERY SMALL pixels. A lens that is not very sharp cannot render a point of light as a single point on the sensor but as a small circle or ellipse which may even split into different colours. If all the light nevertheless fits into a single pixel on the sensor this doesn't matter much but if the pixels are so small that what should be a single point of light on one pixel resolves as a smear of light across several pixels then the image will be soft and the sensor will show up the deficiencies of the lens where a sensor with bigger pixels would not. Therefore, all other things being equal (and they're not, for all sorts of reasons) a 20 megapixel crop sensor will need the very best glass to get the best out of the sensor, where a 20 megapixel full frame sensor might be more forgiving of slightly poorer glass because each pixel is nearly four times bigger.

Bottom line my answer: buying the best optics for your crop sensor camera is never a waste if you want the best from your sensor; it may even be more important than it would be for a full frame sensor. The best optics is not necessarily 'L' glass, although those lenses as well as being optically excellent are usually better made and weather- and dust-proofed too. The optically excellent EF-S lenses I mentioned earlier are not constructed as sturdily as Canon's 'L' glass, although the 60mm macro comes close.


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## Ryan85 (Dec 15, 2014)

I agree with you about the 24-70 2.8 on a crop sensor. You won't be able to get as shallow depth of field with a crop señor as with a ff. I think that's the point he's tying to make that you geting more like a f4 depth of field compared to a 2.8 on ff. But yes you still get the light of a 2.8 lens on a crop sensor


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## Ryan85 (Dec 15, 2014)

GraFax said:


> Ryan85 said:
> 
> 
> > I agree with you about the 24-70 2.8 on a crop sensor. You won't be able to get as shallow depth of field with a crop señor as with a ff. I think that's the point he's tying to make that you geting more like a f4 depth of field compared to a 2.8 on ff. But yes you still get the light of a 2.8 lens on a crop sensor
> ...



Let me know how the 17-55 2.8 works if you get one. I have a 24-105 f4, 16-35 f4, and I've been saving for the 24-70 2.8 but haven't pull the trigger and I'm thinking about the 17-55 2.8 now too.


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## wickidwombat (Dec 15, 2014)

GraFax said:


> Ryan85 said:
> 
> 
> > I agree with you about the 24-70 2.8 on a crop sensor. You won't be able to get as shallow depth of field with a crop señor as with a ff. I think that's the point he's tying to make that you geting more like a f4 depth of field compared to a 2.8 on ff. But yes you still get the light of a 2.8 lens on a crop sensor
> ...


i think the new 16-35 f4 might be a tad sharper over the frame but not by a significant amount
but given the extra zom range the 17-55 gives and an extra stop of light its still the better choice IMO


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## Ryan85 (Dec 15, 2014)

wickidwombat said:


> GraFax said:
> 
> 
> > Ryan85 said:
> ...



Thanks for the reply. I love the 16-35 f4 on my 5d3. Haven't tried it on a crop yet. But after reading about it I'm thinking about trying it out


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## dgatwood (Dec 15, 2014)

Ryan85 said:


> I agree with you about the 24-70 2.8 on a crop sensor. You won't be able to get as shallow depth of field with a crop señor as with a ff. I think that's the point he's tying to make that you geting more like a f4 depth of field compared to a 2.8 on ff. But yes you still get the light of a 2.8 lens on a crop sensor



Depends on how you look at it. I'd argue that with the exception of the f-stop's effect on autofocus, you really *don't* get the light of an f/2.8 lens on a crop sensor. I mean ostensibly yes, if you have two sensors with the same pixel size and you look at a pixel-sized crop, you would see the same amount of light, but that's not the way people use cameras in practice.

People typically use cameras by framing a shot, and then viewing it at screen size or printing it at a desired print size. So the only truly interesting metric is the amount of light that makes up *each square inch of output* at a given size. Using that metric, because a crop sensor sees light from only about 39% of the lens, per square inch of output, a crop body gives you an image produced with only about 39% of the light that you'd get shooting the same shot with a full-frame body (ignoring any differences in light caused by moving closer to the subject, which if included, would make the crop body look even worse by comparison).

When it comes to the actual image projected on the sensor, there's no meaningful difference between using a crop body and using a teleconverter on a full-frame camera—just a little bit of IQ loss caused by the quality of the TC's glass, and maybe a tiny bit of light loss from the glass itself. And we say that using a 1.4X teleconverter makes a lens act like it is a stop slower. By that same standard, using a glorified 1.6X teleconverter (a crop body) makes a lens act like it is 1.35 stops slower. The only real exceptions to that rule are when either A. you'd be cropping the image on a full-frame to match the crop body (the reach-limited case) or B. you're talking about how the autofocus behaves. But in the more general case, you really don't get the benefits of an f/2.8 lens.


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## Ryan85 (Dec 15, 2014)

dgatwood said:


> Ryan85 said:
> 
> 
> > I agree with you about the 24-70 2.8 on a crop sensor. You won't be able to get as shallow depth of field with a crop señor as with a ff. I think that's the point he's tying to make that you geting more like a f4 depth of field compared to a 2.8 on ff. But yes you still get the light of a 2.8 lens on a crop sensor
> ...



You may very well be right I don't know. I've always thought a 2.8 lens is a 2.8 lens whether it's on a ff or crop. Other than I know I'll get shallower depth of field with a ff and more depth of field with a crop at the same apertures.


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## candc (Dec 15, 2014)

There is some discussion about using the 16-35 f/4 on a crop body. If you already have one and want to use it for that great but don't buy one for that. The Sigma 18-35 is much better. It is sharper and its f/1.8 so you can get decent background blur in a normal zoom which is difficult with other lenses on aps-c.


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## Ryan85 (Dec 15, 2014)

GraFax I have and use the 16-35 f4 with the 5d3 and it is a great lens.


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## Ryan85 (Dec 15, 2014)

GraFax said:


> Ryan85 said:
> 
> 
> > GraFax I have and use the 16-35 f4 with the 5d3 and it is a great lens.
> ...



Yep I hear that.


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## Joey (Dec 15, 2014)

Ryan85 said:


> dgatwood said:
> 
> 
> > Ryan85 said:
> ...


An f/2.8 lens is an f/2.8 lens. f/2.8 is a formula, referring to the focal length of the lens divided by the effective maximum aperture of the lens (usually more-or-less the diameter of the outer element on a prime lens). Thus a telephoto lens needs bigger elements than a wide angle lens for the same f/2.8 (or whatever) aperture.
It's a red herring to introduce arguments about teleconverters into this discussion. A 1.4x converter doesn't 'make a lens act as though it's a stop slower', it really is a stop slower. The 1.4x converter changes the focal length of the lens combination but it doesn't change the size of the elements so the aperture formula changes. A 50mm lens with an effective diameter of 25mm has a maximum of aperture of 50/2 or f/2. Add a 2x converter and the lens combination now has a focal length of 100mm and the same 25mm diameter gives an aperture of 100/4 or f/4. It's maths. Nothing to do with the sensor.

The central paragraph of dgatwood's post is hard to follow but the physics works like this: the aperture of a lens defines how bright the image circle on the sensor is. Whether you use most of the image circle on a full frame sensor or less of the image circle (ff lens on crop body) the brightness of the image is the same - you're just using all or part of it. There will be no impact on image quality unless the individual pixels are of different sizes - and the pixels on a ff body are usually a lot bigger than the pixels on a crop body which has both benefits and disadvantages as discussed elsewhere on this thread and others. Some people including, I think, Tony Northrup, are confusing image brightness with 'total light capture' implying that unless you can use all the light that's coming through the lens you're losing quality which is plainly not so - we don't use, nor do we want to use, the edges of the image circle because the sharpness drops off and other distortions show up more.

The topic of depth of field - shallower depth of field on a ff and deeper dof on a crop body - is another subject and an interesting one. Make an image using a ff sensor of a particular scene and observe the depth of field - how much of the scene in front of and behind the point of focus is in acceptable focus. Now crop your image in software to the equivalent size of a crop sensor (in Canon terms, that's reducing the linear dimensions by 1.6) and look at the scene that is left. The depth of field hasn't changed, of course, it's the same image - you just have less of it. Now use the same lens at the same aperture from the same taking position on a crop body and take the same picture. You will get the same image you got after cropping the ff image. And the depth of field will be the same too because you used the same lens from the same taking position. Those are the elements that affect depth of field - taking position, focus distance, focal length of the lens and lens aperture. Sensor size does not of itself affect depth of field. HOWEVER - if you switch from ff to crop and change either the focal length of the lens or the taking position so that you get the same field of view as you had for the ff image UNCROPPED then you will get more depth of field. That's not because you're using a crop sensor, it's because you're using a shorter focal length lens or you're taking the picture from further away to get the same field of view as you got with the ff sensor. Since that's how we generally use our cameras, that's how we perceive it - we get more depth of field when we use a crop camera, because we're using shorter focal length lenses to get the same pictures.


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## wyldeguy (Dec 15, 2014)

+1 to Joey. That is probably the best explanation I've ever heard and also one of the most intelligent arguments I've seen on a forum in years. I had actually believed that none sense about depth of field on crop bodies until now. Thanks


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## Joey (Dec 15, 2014)

wyldeguy said:


> +1 to Joey. That is probably the best explanation I've ever heard and also one of the most intelligent arguments I've seen on a forum in years. I had actually believed that none sense about depth of field on crop bodies until now. Thanks


Thank you! I'm blushing...


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## wyldeguy (Dec 15, 2014)

You're welcome


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## weixing (Dec 15, 2014)

Hi,


wyldeguy said:


> +1 to Joey. That is probably the best explanation I've ever heard and also one of the most intelligent arguments I've seen on a forum in years. I had actually believed that none sense about depth of field on crop bodies until now. Thanks


 Actually, it's not nonsense, it's just that most people assume that the image framing is the same (same field of view) when mentioning the depth of field on crop camera.... to get the same image framing (same field of view... eg. half body portrait on FF camera = half body portrait on crop camera), you need to be further away from the subject or use a shorter lens at the same distance... which will increase the depth of field.

Have a nice day.


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## Helios68 (Dec 15, 2014)

Hi,

I have never tested a FF camera intensively. But I do own a couple of EF lenses, including the 70-200 f/2.8 and 100L. What I can say is that they produce just amazing pictures even on my T5i/700D. I do not want to say that it performs as good as a FF body (which I don't expect), but it is definitely crap to say it is not usable at all !

I have compared the kit lens 18-55 (quite acceptable) with the 100L and 70-200L and it is worth the price ! But if it is just about a "Canon bashing", I can understand this point of view...

Regards.


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## Jane (Dec 15, 2014)

Way to go, Joey. Well argued, well said.


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## privatebydesign (Dec 15, 2014)

Joey said:


> Ryan85 said:
> 
> 
> > dgatwood said:
> ...



I agree that this is generally a nice explanation, particularly about light intensity. However regarding the highlighted section and on, it is wrong.

DOF relies on two factors only, physical aperture (not numerical value) and subject magnification. Aperture seems easy for most of us to understand, though we must also understand the difference between apparent physical aperture and the numerical aperture; where so many slip up is subject magnification. The print or screen size, and viewing distance, both impact DOF. 

There are three situations for comparison and you have to decide which method you use because the outcome is different.

1/ Two people stand next to each other, one has a ff the other a crop camera, both have the 400 f5.6 and are shooting a nesting eagle a long way away. Both have to crop their images to get the framing they want. Obviously the ff image is cropped more but that is irrelevant, the eagle is projected on to both sensors the same size and both images are cropped to the same framing and reproduced the same size (on screen the same size) so the DOF is identical, indeed both images are identical. DOF is the same.

Same reproduction size, same physical aperture = same DOF.


2/ Both photographers decide they want to show a scene setting image and change their lenses to the widest they have, both have a 35mm f2 IS and use that to take a shot, obviously the framing is different. Both show the resulting image full screen on the same sized monitor, the crop image shows each element of the scene larger because it has less fov (framing). The DOF for the crop camera is less than the ff camera. Why is this? Because the reproduction ratio of the crop camera is higher and reproduction ratio is key to DOF. DOF is less with the crop camera.

Different reproduction size, same physical aperture = different DOF.


3/ The crop camera photographer remembers in the bottom of his bag he has an 11-22, they both stand next to each other and use the same settings, with different focal lengths to take 'the same' image. When viewed on a screen the same size the crop camera has more DOF even though it is enlarged more, why is this? Well the actual subject size on screen is the same for both images, but the aperture, although the same number, is physically smaller for the crop camera. The FF camera has a 35mm @ f10, or a 3.5mm aperture opening; the crop camera has a 35mm/1.6= 21mm @ f10, or a 2.1mm aperture opening. The smaller the apparent aperture the more dof. DOF is greater on the crop camera.

Same reproduction size, different physical aperture = different DOF.


So, as can be seen, sensor size in and of itself does not impact dof, how you choose to display that resulting capture does. You cannot disassociate end reproduction size from the dof calculation, you can make any comparison you like but you need to understand the impact of those different choices. 


The DOF is not greater on crop cameras in the most common comparison because we use a shorter focal length, it is greater because we use a smaller physical aperture to achieve the same exposure settings.


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## Joey (Dec 15, 2014)

privatebydesign said:


> Joey said:
> 
> 
> > Ryan85 said:
> ...


Are you using DOF (depth of field) to refer to something other than what I understand it to be - How much of the scene in front and behind the point focussed on is acceptably in focus? The four factors I list and you highlighted in red certainly do affect depth of field (just checked with Wikipedia to make sure I hadn't drifted into a parallel universe...)
However, I may possibly get your point to an extent: Technically, depth of field is calculated using the circle of confusion - the size of the circular out of focus image created by a point of light. The further out of focus, the larger the circle. Only one plane in any image is actually 'in focus' but a range of planes in front of and behind that plane are considered acceptably in focus because the circles of confusion created at these distances are small enough to be seen as points. It is true that what is 'acceptably in focus' will change with enlargement of the final image and the viewing distance but that is a subjective matter. There are figures for 'acceptable' circle of confusion for various formats and the figure used for 35mm cine for instance is larger than that for 16mm. However in still photography we are much more rigorous and 'acceptable' circle of confusion is vanishingly small. I generally consider that if I consider an image (or region of an image) out of focus on a 12 x 16 print, it will also be out of focus at 6 x 8, less so, but still unacceptably out of focus. Similarly the difference between full frame and crop sensors.
Interestingly, and touched on by the Wikipedia article, the difference in the amount of enlargement involved in producing a given image from a crop sensor rather than a full frame and the effect on the acceptable circle of confusion size should mean you get LESS depth of field from a crop camera. Most people's perception though, as I mentioned in my earlier post, is that you get MORE depth of field from a crop camera, which is because you use shorter focal length lenses or work from a greater distance to get the same field of view. I think that's part of the point you're making with your three scenarios. As Wikipedia puts it: "The comparative DOFs of two different format sizes depend on the conditions of the comparison. The DOF for the smaller format can be either more than or less than that for the larger format. " 

Your last statement "The DOF is not greater on crop cameras in the most common comparison because we use a shorter focal length, it is greater because we use a smaller physical aperture to achieve the same exposure settings." and the reasoning earlier in your post, seems to make an argument where no argument is necessary. We refer to lens' aperture as, for instance, f/2.8 in order to factor the focal length of the lens into the actual aperture of the lens to give a figure describing how bright the image circle will be. That's why we can say that focal length and aperture number both impact the depth of field.
I have re-drafted this response several times in an attempt to get it just right - apologies if you read an earlier version of this post...


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## Joey (Dec 15, 2014)

Jane said:


> Way to go, Joey. Well argued, well said.


Thank you Jane.


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## stefang (Dec 15, 2014)

I read a lot of bashing on the video by Tony Northrup over here, so I was curious and watched it. What I see is that he basically is right in his conclusions:
- The best APS-C lenses may be sharper than an equivalent FF lens on the same body
- When you are forced to crop you photo's to at least APS-C size, you may be better off with an APS-C body
That there may be very good reasons other than sharpness to buy FF lenses and bodies does not invalidate his conclusions....


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## Ryan85 (Dec 15, 2014)

Helios68 said:


> Hi,
> 
> I have never tested a FF camera intensively. But I do own a couple of EF lenses, including the 70-200 f/2.8 and 100L. What I can say is that they produce just amazing pictures even on my T5i/700D. I do not want to say that it performs as good as a FF body (which I don't expect), but it is definitely crap to say it is not usable at all !
> 
> ...


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## Chipcago (Dec 16, 2014)

Hi -- 

New member and not super techie, so please be nice. Also, I am a Tony/Chelsea fan, -- they are nice, goofy and earnest, IMHO, so again, please be nice. That said, I do get very confused by Tony's explanations. Here's why -- I think -- prior to digital phtotgraphy, using a 35 mm camera meant that light got to film causing a photochemical reaction which produced a picture. So, all the math was based on a constant. Now, there are ff digital cameras, which are "true" 35 mm equivalents and crop sensor cameras, which are camera with sensors that are smaller than 35 mm by varying degrees. In addition, the medium is not film, so instead of a photochemical reaction, the cameras are taking in information communicated by light and reacting electronically. 

Since both ff and crop sensors are pocessing the same light and then electronically converting that to an image, I don't understand his comments about the same amount of light getting to the sensor. In other words, if person A is using a ff to take a picture of statue 1 with a field of view of X and person B is using a crop to take a picture of statue 1 and adjusts his position to have the same field of view of X and both are using the same lens and the same focal length, isn't everything the same? Both cameras are working to take the same eaxact picture, with the same light coming to the sensor. The only difference I can think of is that if both camera's are 20 MP then the FF pixells are going to be larger. So, I get confused about his "sensor light collecting" statements, because it seems to me that this would only be relevant if the argument was about comparing a 35 mm film camera to a smaller sized film camera. It seems to me that the argument with ff versus crop has to do with how a 20 MP ff processes the electronic information versus a 20 MP crop, not about the light getting to the sensor. 

Thanks in advance for the assistance.

Chip


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## Ryan85 (Dec 16, 2014)

Chipcago said:


> Hi --
> 
> New member and not super techie, so please be nice. Also, I am a Tony/Chelsea fan, -- they are nice, goofy and earnest, IMHO, so again, please be nice. That said, I do get very confused by Tony's explanations. Here's why -- I think -- prior to digital phtotgraphy, using a 35 mm camera meant that light got to film causing a photochemical reaction which produced a picture. So, all the math was based on a constant. Now, there are ff digital cameras, which are "true" 35 mm equivalents and crop sensor cameras, which are camera with sensors that are smaller than 35 mm by varying degrees. In addition, the medium is not film, so instead of a photochemical reaction, the cameras are taking in information communicated by light and reacting electronically.
> 
> ...



Don't worry to much if there a little mean to you they don't like Tony Northrup here much. I don't agree with everything he says but he's ok. I think he gives his honest opinion.

I'm not a techie either but I'll explain your question the best I can. I'm sure others can and will explain it better than me or correct me if I'm wrong. 

So a FF sensor is the equivalent of a 35 MM film camera. A crop (sensor aps-c) has a smaller sensor. So a 100mm lens on a FF is 100mm lens. On a Canon crop sensor you have to multiply the the lens by 1.6. Since the sensor is smaller. So that same 100mm lens on a crop sensor camera would be a 160mm. A 50mm on FF is a 50mm. On a crop sensor a 50mm is a 80mm lens. And so on.

Now 100mm 2.8 on a FF is a 100mm 2.8. That 100mm 2.8 on a Canon crop sensor is 160mm 2.8. You multiply the focal length by 1.6 on your crop sensor but the aperture/ f number stays the same. 

Now with a FF your going to have a shallower depth of field. With a crop sensor you're going to have more depth of field. I don't know why but that's how it is. It's the sensor size and physics. I think when Tony say there's less light on a crop sensor he's actually meaning a 2.8 lens acts like a f4.5 lens because you don't get as shallow depth of field with a crop sensor. 

I hope that helps with your question. I wouldn't worry to much just shoot and enjoy it.


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## tcmatthews (Dec 16, 2014)

Chipcago said:


> Hi --
> 
> New member and not super techie, so please be nice. Also, I am a Tony/Chelsea fan, -- they are nice, goofy and earnest, IMHO, so again, please be nice. That said, I do get very confused by Tony's explanations. Here's why -- I think -- prior to digital phtotgraphy, using a 35 mm camera meant that light got to film causing a photochemical reaction which produced a picture. So, all the math was based on a constant. Now, there are ff digital cameras, which are "true" 35 mm equivalents and crop sensor cameras, which are camera with sensors that are smaller than 35 mm by varying degrees. In addition, the medium is not film, so instead of a photochemical reaction, the cameras are taking in information communicated by light and reacting electronically.
> 
> ...



Tony went a little off the reservation when it came to ISO. A full frame sensor only gathers more light because it has a larger area. Crop cameras are not providing more amplification to get the same brightness because they are smaller. More than likely the 7d and 5d II provide close to the same amplification per pixel. ISO performance(noise) is largely a function of the efficiency and size of the image pixels. 

His ISO noise math only works out because all the cameras used have close to the same amount of pixels. It is true when comparing film cameras. But it brakes down completely in digital where pixel pitch takes over. 
Perhaps I just made his point that ISO is a bad measurement for digital. But personally I think that constant exposure behavior between camera formats is more important. 

For an Ideal lens (constant intensity across the image circle) the intensity of light hitting a full frame, APC or m43 will be the same. This will lead to the same ISO, same shutter speed etc. Light intensity effects ISO. Full frame cameras have a larger Area and typically have larger pixels. Therefore it collects more total light because of its larger area. To give a crop or m43 the same total light you have to raise the light intensity. 



Chipcago said:


> It seems to me that the argument with ff versus crop has to do with how a 20 MP ff processes the electronic information versus a 20 MP crop, not about the light getting to the sensor.



Pretty much. Furthermore an argument about light hitting the sensor is a bit of an over simplification. Not really helpful without a discussion of pixel pitch.


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## BozillaNZ (Dec 16, 2014)

When you mount the same FF lens to a APS-C 1.6x crop sensor, you are essentially only capturing 39% of the light (photons) the lens collects, and throws away the rest of the 61%. No matter how you spin, that is a loss.

So yes, using FF lens on APS-C is wasteful, because you could as well use a native APS-C lens with the same focal length and aperture, and it will be a lot smaller and lighter because the glass in it collects light from a narrower angle of view so it doesn't have to be as large.


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## Don Haines (Dec 16, 2014)

Chipcago said:


> Hi --
> 
> New member and not super techie, so please be nice. Also, I am a Tony/Chelsea fan, -- they are nice, goofy and earnest, IMHO, so again, please be nice. That said, I do get very confused by Tony's explanations. Here's why -- I think -- prior to digital phtotgraphy, using a 35 mm camera meant that light got to film causing a photochemical reaction which produced a picture. So, all the math was based on a constant. Now, there are ff digital cameras, which are "true" 35 mm equivalents and crop sensor cameras, which are camera with sensors that are smaller than 35 mm by varying degrees. In addition, the medium is not film, so instead of a photochemical reaction, the cameras are taking in information communicated by light and reacting electronically.
> 
> ...


Hi,

An awful lot of people get mixed up with "equivalent"

let's start with the crop factor... I pick up a crop camera and put a 100mm lens on it and take a picture of an object 100 feet away. Standing in the same spot, if I want to take an identically framed picture on a FF camera, I need to use a 160mm lens on it. That is your 1.6X crop factor. very easy to understand....

Things get fun when you think about depth of field..... shooting at F2.8 and at 100 feet that 160mm lens has a DOF of about 20 feet, while the 100mm lens has a 55 foot DOF... you would have to stop down the 100mm lens on the crop camera to F1.2 to get the same depth of field as the 160mm lens on the FF camera.

that's what happens if you are stationary, sometime you can zoom with your feet. If you shoot with the FF camera at 100 feet away, you can get the same field of view with the crop camera from 160 feet.... there's that 1.6X crop factor again.

If you shoot with a 100mmF2.8 lens on the crop camera and move to 160 feet with the crop camera and the same 100F2.8 lens , you get the same field of view AT THE FOCUS PLANE, but everything else changes. Your depth of field with the FF camera is still 20 feet, but with the crop camera it is now 160 feet of DOF. To make matters even more confusing, you now have a different perspective on the two shots so they are not and can never be identical. The crop camera is now going to be seeing distant objects larger and near objects smaller in relation to how the FF camera shows them in relation to the object at 100 feet that you are focused on.

As far as light goes, that 100mm F2.8 lens remains as a 100mmF2.8 lens no matter which camera you mount it on. It collects the exact same amount of light. Your exposure times and ISO settings are identical between the two cameras. The difference is the amount of the light that is used. The FF sensor is 2.56 times larger than the crop sensor (1.6 squared). If both cameras are the same number of megapixels, this means that the pixels in the FF camera will get 2 1/2 times the light as the pixels do in the crop camera. If you are in poor light this is a big deal, but in good light it really does not matter.... it's kind of like the difference between shooting at ISO 200 and 500 (good light, not noticeable) or between shooting at ISO 10,000 and 25,600 (poor light, very noticeable difference)

and then we have the corners/sweet spot tradeoff.... Lenses are always sharpest at the center and that's the part crop used most, while FF cameras can have problems with the corners.... but since this is so incredibly lens dependant, there is no answer here....

another factor that virtually nobody considers is economy of scale and limited design and manufacturing resources. Looking at that 100mmF2.8 lens, you could design one specifically for FF and another one specifically for crop, but there would be no improvement in image quality and the price of both would be driven upwards.

In short, there is no such thing as equivalence between a crop lens and a FF lens and there is no reason to not use a FF lens on a crop sensor.


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## Don Haines (Dec 16, 2014)

BozillaNZ said:


> When you mount the same FF lens to a APS-C 1.6x crop sensor, you are essentially only capturing 39% of the light (photons) the lens collects, and throws away the rest of the 61%. No matter how you spin, that is a loss.
> 
> So yes, using FF lens on APS-C is wasteful, because you could as well use a native APS-C lens with the same focal length and aperture, and it will be a lot smaller and lighter because the glass in it collects light from a narrower angle of view so it doesn't have to be as large.



The only elements that would be smaller are the small elements nearest the camera. The largest grouping would be the same. on lenses longer than 50 or 60 mm it makes a hardly recognizable difference.


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## privatebydesign (Dec 16, 2014)

> Are you using DOF (depth of field) to refer to something other than what I understand it to be - How much of the scene in front and behind the point focussed on is acceptably in focus?



No, we are referring to the same thing.



> The four factors I list and you highlighted in red certainly do affect depth of field (just checked with Wikipedia to make sure I hadn't drifted into a parallel universe...)



They are just factors to define the two core elements, aperture size and magnification, that is it, those are the only two numbers you need to work out DOF after you define a size for your CoC. All those other number you plug in to dof calculators are simply working out the subject magnification, the aperture size and coming out with a number for a pre defined CoC. You cannot work out DOF if you do not know those two numbers, if you know the aperture number but not the focal length you cannot work out DOF, if you know the size of the aperture opening you can.



> It is true that what is 'acceptably in focus' will change with enlargement of the final image and the viewing distance but that is a subjective matter.



DOF is entirely subjective. That is why in the definition of DOF the word "acceptably" precedes sharp; acceptable to what? 



> There are figures for 'acceptable' circle of confusion for various formats



Yes but what does that refer to? As a file on a HDD an image has no DoF, am image does not have an intrinsic DoF value until it is given an output size and viewing distance, these have become normalised but they are the defining factors. The aperture size creates the DoF, the output magnification defines it. The CoC figure is generally an 8"x10" print viewed at 12", which corresponds to any other print viewed at the distance of its diagonal. People with better acuity will always find 'standard' DoF wanting.



> Interestingly, and touched on by the Wikipedia article, the difference in the amount of enlargement involved in producing a given image from a crop sensor rather than a full frame and the effect on the acceptable circle of confusion size should mean you get LESS depth of field from a crop camera.



That is exactly what I wrote in my scenario number 2, _"The DOF for the crop camera is less than the ff camera."_ if a comparison is made of that shooting scenario.



> As Wikipedia puts it:"The comparative DOFs of two different format sizes depend on the conditions of the comparison. The DOF for the smaller format can be either more than or less than that for the larger format. "



I know, that is why I gave examples of how that can be illustrated, along with the third option, scenario 1, where the DoF can be the same from both formats. As I said, _"There are three situations for comparison and you have to decide which method you use because the outcome is different."_

So the question can be boiled down to a core element, why does a shorter focal length result in deeper dof? The answer is a shorter focal length results in smaller subject magnification, subject magnification is a core element of DoF, and, for the same exposure value a shorter lens has a smaller physical aperture for the same numerical aperture value, and aperture size is the other core element of DoF.


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## Joey (Dec 16, 2014)

privatebydesign said:


> > It is true that what is 'acceptably in focus' will change with enlargement of the final image and the viewing distance but that is a subjective matter.
> 
> 
> 
> ...



I reckon we're in agreement then. We owe a debt of gratitude to Tony Northrup for giving us the motivation to engage in debate about these matters. I admit to a little nostalgia for the days when lenses had depth-of-field markings...


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## BozillaNZ (Dec 16, 2014)

Don Haines said:


> The only elements that would be smaller are the small elements nearest the camera. The largest grouping would be the same. on lenses longer than 50 or 60 mm it makes a hardly recognizable difference.



Telephoto yes, wide angle no. Just look at EF 24 2.8 and EF-s 24 2.8. The EF-s one is actually a 38 equivalent FoV one so it's narrower and a lot smaller.

Using a 70-200 on crop would be less wasteful than using a 16-35


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## Don Haines (Dec 16, 2014)

BozillaNZ said:


> Don Haines said:
> 
> 
> > The only elements that would be smaller are the small elements nearest the camera. The largest grouping would be the same. on lenses longer than 50 or 60 mm it makes a hardly recognizable difference.
> ...


or you could compare it against the EF40 F2.8.....

You can't really compare pancakes against normal lenses... Although Canon's pancakes are very high quality designs, and the performance for the price is stellar, there are sacrifices in IQ compared to regular lens of similar design and materials.... the sharper you bend light, the greater these problems get, particularly the prism effect where you start focusing different colours in different places.

but more to the point, you are correct in saying that for the wider angles, there are size and weight savings with EFS mounts...... but the large elements still remain the same size.


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## erjlphoto (Dec 23, 2014)

striperone said:


> From the video I've posted below, it looks as though it's a (big) waste of money to purchase high rent full frame glass
> 
> ...I wanted the 7D mark II with a Canon EF 70-200mm f/2.8L IS II USM Lens. If what I'm seeing in the video below is correct and I sure would assume so, that this combination is a total waste of money....
> 
> Actually, that sounds like a great combination for action/sports or even general use. You will likely have the 70-200 mmii is long after you have replaced the 7D mk ii. The lens will still be awesome if you eventually go FF.


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## tron (Dec 23, 2014)

dcm said:


> It's no waste, particularly if you might get a FF body down the road. Glass lasts a long time, bodies change faster. I never used the kit lens on my T2i or purchased any EF-S lenses for it. I purchased L glass to go with it and and kept adding to the collection. The 24-105L was my first L and it got a lot of use. Three years later I purchased a 6D. Some lenses that are soft around the edge might even benefit from a crop sensor ;-)
> 
> I later decided to go the M route for my crop sensor and added some EF-M lenses for it. I occasionally mount some L glass on it.


+1 Exactly! I think FF L lenses is the obvious way to go if someone intends to upgrade to FF.

The only thing someone with APS-C camera may have to get in EF-S is 10-22 or 10-18.


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## tron (Dec 23, 2014)

I haven't watched any of his videos and now that I read this thread I do not think I will in the future!


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