# Full Frame Lens Choice to Match 7D and 17-55 2.8 IS.



## jon_charron (Mar 6, 2013)

I'm going to a full frame camera and starting over with glass after a theft. I do photos and video, so the 17-55 2.8 IS has been my most widely used lens (with my former 7D body). Photography wise, I have used it extensively for event photography. For instance, in clubs and low light events like wedding dances, I use second curtain sync flash at 2.8 and shutter speeds as low as 1.5-0.5 second range.

The 2.8 and the IS mode are equally important in this case, and have allowed me to do some great shots I couldn't really duplicate easily with any other full frame combo I know of. Since I sometimes zoom or twist the camera while the shutter is open, the zoom is also important, so one of the new medium primes with IS is also out. 

I want to go full frame, but I feel like without a 2.8 zoom in this range with IS, that matches the image quality of the 17-55, I will miss a ton of great shots I'm kind of known for. Any advice here?

Here are some sample images with the combo I had before:







































I'm trying to wrap my head around if increasing ISO (compared to what was useable on the 7d) with the 5D iii or 6D will offset the loss of speed from the lens if I go with say, the 24-105L. My gut says, yes...and no.


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## Random Orbits (Mar 6, 2013)

*Re: Duplicate APS-C and 17-55 2.8 IS in Full Frame?*

It depends on what your budget is. The most affordable way is to get the 24-105 with 6D kit. The 24-105 will most likely match the DOF and range that you were used to with the 17-55. The 24-105 would give you slightly shallower DOF because it's paired with a larger sensor. 

If you can afford more, a step up on the lens side would be the Tamron 24-70 VC. The Tamron would give you markedly shallower DOF at f/2.8 and give you less noise headroom than the crop camera.


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## jon_charron (Mar 6, 2013)

*Re: Duplicate APS-C and 17-55 2.8 IS in Full Frame?*



Random Orbits said:


> It depends on what your budget is. The most affordable way is to get the 24-105 with 6D kit. The 24-105 will most likely match the DOF and range that you were used to with the 17-55. The 24-105 would give you slightly shallower DOF because it's paired with a larger sensor.
> 
> If you can afford more, a step up on the lens side would be the Tamron 24-70 VC. The Tamron would give you markedly shallower DOF at f/2.8 and give you less noise headroom than the crop camera.



I was just checking that lens out online. I have to say that I could only get the shots I've shown consistently with the lens at 2.8. Going up to f4 made a huge difference and was not really an option. DOF is not a concern for this type of shooting, especially since flash will punch out the DOF anyway. My concern with the Tamron is well...it's a Tamron, but also the focus speed and accuracy (which I've heard is not great). It's also supposed to be very heavy, which if the other factors are good, I can live with. I shoot most these using one hand, camera in the right and flash in the left with a hacked flash snyc cable and an RJ45 cable to make it a bit longer. The only time I use two hands is to quickly change the zoom to frame, and the rare but necessary occasion that I want to zoom while shutter is open. I was really hoping Canon would finally come out with the 24-70 2.8 IS L, but no. They had to introduce that stupid, redundant 24-70 f4 IS, but that is another thread. 

Forgot to mention, I'm not really worried about the cost of the lens, and yes the 6D is one of the bodies I'm looking at. I would get the kit lens, but I don't think it will work for me at F4.


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## Random Orbits (Mar 6, 2013)

FFs perform better at higher ISOs due to the larger sensor size. You could use the lens at f/4 and double the ISO and still get a better/cleaner results than the current crop of Canon crop cameras.

In any case, it'd make sense to get a FF camera with 24-105. Try it and sell it if it doesn't work for you. You can sell it for more than the difference between the camera only/kit price. You could also try renting the Tamron and see if it works for you in the way you shoot.

Nice images BTW.


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## neuroanatomist (Mar 6, 2013)

A 6D or 5DIII will give you 1.5-2 stops better ISO performance. If you give up a stop going from f/2.8 to f/4, you're still well ahead, plus the 24-105 is both wider and longer. If you're shooting in low light, FF trumps APS-C hands down.


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## jon_charron (Mar 6, 2013)

Random Orbits said:


> Nice images BTW.



Thanks.

Yes I'm still trying to wrap my head around that. I understand the ISO and FF sensor issue, but an example would be shooting BIF with a 70-200 2.8 IS II at 200/2.8 vs. 70-200 f4 IS at 200/4. Even tried a 500 f4 on a FF. I crank the ISO up and still can't get the keeper rate as high at 1/1600 and higher using f4 compared f2.8. 2.8 always wins when both have IS and the ISO is similar stops. Maybe it's more a focusing issue. I certainly came to know the intricacies of the 7D while I had it and used to kind of irritate the BIF guys with the bigger F4 lenses at times when shooting side by side, especially in the golden hour.


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## Eli (Mar 6, 2013)

But are your BIF non keepers due to motion blur or just completely out of focus?
The 5d mkiii + 24-105 f4l will be better than your 7d + 17-55 f2.8 in almost every way for your nightclub work, you could jack up the ISO by 2 stops and still have cleaner images.
You could have the same shutter speed, and lets say on your 7d you'd have to use iso6400 at f2.8, with the 5d mkiii, and same shutter speed, you'd use iso12800 and f4, but the image will still be cleaner than your 7d.
If not just get the tamron 24-70 vc f2.8 and get the best of both worlds in regards to aperture and IS, doesn't cost that much more..


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## neuroanatomist (Mar 6, 2013)

jon_charron said:


> I crank the ISO up and still can't get the keeper rate as high at 1/1600 and higher using f4 compared f2.8. 2.8 always wins when both have IS and *the ISO is similar stops*. Maybe it's more a focusing issue. I certainly came to know the intricacies of the 7D while I had it and used to kind of irritate the BIF guys with the bigger F4 lenses at times when shooting side by side, especially in the golden hour.


That's the point. Sensor size does not affect exposure. Shooting at 1/1600 s, f/2.8, ISO 3200 on APS-C, if you switch to f/4 and keep 1/1600 s and ISO 3200, you'll have half as much light per unit area hitting the sensor. Same would be true with the teeny sensor on my PowerShot S100. 

What sensor size does affect is the amount of noise at a given ISO. So compared to 1/1600 s, f/2.8, ISO 3200 on the 7D, you could shoot the FF camera at 1/1600 s, f/4, ISO 6400 and have lower image noise (better IQ) or you could shoot at *1/3200 s*, f/4, ISO 12800 and have similar IQ to the 7D shot at f/2.8, ISO 3200 - i.e., a _faster_ shutter speed with the slower lens and equivalent IQ.

Here's a shot with one of one of those 'bigger f/4 lenses' at dusk on an overcast day, FF camera and *ISO 6400*. Same shot on a 7D would be unusably noisy (and in this case, f/2.8 isn't an option...). 




EOS 1D X, EF 600mm f/4L IS II USM, 1/250 s, f/4, ISO 6400


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## Dylan777 (Mar 6, 2013)

About the NEW - Tamron 24-70 f2.8 VC(IS)


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## wickidwombat (Mar 6, 2013)

*Re: Duplicate APS-C and 17-55 2.8 IS in Full Frame?*



jon_charron said:


> Going up to f4 made a huge difference and was not really an option. DOF is not a concern for this type of shooting, especially since flash will punch out the DOF anyway. My concern with the Tamron is well...it's a Tamron,


Ummmm I dont quite think you understand the concept of DOF here flash and DOF are two completely mutually exclussive aspects. ie flash has precisely zero effect on DOF. DOF is a function of the lens and sensor the flash simply provide light for the exposure

the tamron fear is totally understandable however.

the f4 on full frame is essentially going to give you the equivalent as the 2.8 on your crop
on the 5Dmk3 at events even shooting iso 16,000 is fine where as with crop its 1600 maybe 3200 at a push
iso 16000 on the 5dmk3 takes about the same NR and processing as 1600 does on crop IMO


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## TrumpetPower! (Mar 6, 2013)

One of the regulars here -- sorry, I don't remember which one -- often makes the point that the 24-105 on full frame is superior in every way to the 17-55 on a crop. It's wider and longer, you can get a shallower depth of field, and you get less noise.

If you like the 17-55, you'll absolutely love the 24-105 on a full frame camera.

Cheers,

b&


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## robbymack (Mar 6, 2013)

Well if you must have 2.8 and IS in a FF compatible mid range zoom you have only one choice, it's the tamron. I own it, is it perfect? No, but what lens is? For what you spend its fantastic. You can spend an awful lot more for maybe a 10% iq improvement with the canon 24-70ii but you lose IS and a cool grand in the process. considering what you posted you shoot I don't see your clients really caring too much. After all anything you give them is a thousand times better than the millions of (insert any modern smartphone here) pictures they have been taking and adding crappy Instagram filters to.


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## neuroanatomist (Mar 6, 2013)

TrumpetPower! said:


> One of the regulars here -- sorry, I don't remember which one -- often makes the point that the 24-105 on full frame is superior in every way to the 17-55 on a crop. It's wider and longer, you can get a shallower depth of field, and you get less noise.



Every way but one...you lose the f/2.8 high precision center AF point. A very worthwhile trade, IMO.


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## TrumpetPower! (Mar 6, 2013)

neuroanatomist said:


> TrumpetPower! said:
> 
> 
> > One of the regulars here -- sorry, I don't remember which one -- often makes the point that the 24-105 on full frame is superior in every way to the 17-55 on a crop. It's wider and longer, you can get a shallower depth of field, and you get less noise.
> ...



True -- assuming, of course, the camera itself has an f/2.8 high precision center AF point. If I remember right, the Rebels at least don't, even if Jon's 7D does....

b&


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## neuroanatomist (Mar 7, 2013)

TrumpetPower! said:


> True -- assuming, of course, the camera itself has an f/2.8 high precision center AF point. If I remember right, the Rebels at least don't, even if Jon's 7D does....



Rebel bodies starting with the XTi/400D have a high-precision f/2.8 center AF point, although the 'high precision f/2.8' part if the cross-type point is a single-orientation line sensor. The T4i/650D got the 40D/50D/60D AF sensor with the dual-cross center point similar to the 7D's center point.


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## jon_charron (Mar 7, 2013)

*Re: Duplicate APS-C and 17-55 2.8 IS in Full Frame?*



wickidwombat said:


> Ummmm I dont quite think you understand the concept of DOF here flash and DOF are two completely mutually exclussive aspects. ie flash has precisely zero effect on DOF. DOF is a function of the lens and sensor the flash simply provide light for the exposure.



I understand DOF and the fact that a FF sensor has thinner DOF than crop with same lens. I think I am misunderstanding the relationship between flash and DOF, but after years of taking photos, my recollection is that flash will bring slightly more into focus than without it. Could be wrong. I admit I switched to a crop back about 6 years ago and have done most of my shooting with that, but even my 35mm film days I recall a flash bringing more into focus. I know the flash stops action and brings the subject into focus, so I'm thinking my mind is fooling me in the light's relationship to DOF. 

In any case, I'm not concerned about DOF. 2.8 on FF and a flash should be fine for this kind of photography. I'll still have my subjects plenty in focus, and I can always turn it to f4 if DOF is too thin. If f4 is the only option in the Canon line, then hopefully that works. If not, I'll sell it and try the Tamron. For video, that thinner DOF a 2.8 provides would be much more valuable. I wish Canon made a wide zoom L lens that was 2.8 IS or faster.


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## jon_charron (Mar 7, 2013)

robbymack said:


> Well if you must have 2.8 and IS in a FF compatible mid range zoom you have only one choice, it's the tamron. I own it, is it perfect? No, but what lens is? For what you spend its fantastic. You can spend an awful lot more for maybe a 10% iq improvement with the canon 24-70ii but you lose IS and a cool grand in the process. considering what you posted you shoot I don't see your clients really caring too much. After all anything you give them is a thousand times better than the millions of (insert any modern smartphone here) pictures they have been taking and adding crappy Instagram filters to.



Those aren't my clients, and at a professional event or wedding reception, I need something sharp. Those are unretouched low-res jpegs, but they are pretty sharp RAW out of the camera considering the style. They would not have been near as good with an inferior lens. The 17-55 is sharp, and I strive for sharp images and to own sharp glass. I have tried a 24-70L II on a 5D II at a wedding with a flash, and I struggled to get the same kind of shots, especially as easily as I did with my 7D and the 17-55 2.8 IS. Again, some of that may have been the 5D II's inability to focus as sell in low light, but IS had plenty to do with it. 

I'm not afraid to spend money on glass. I had several L lenses. If the 24-70II would work for me, I would gladly pay the dough to get one. And I'd pay even more again for IS. In the end I'll likely need to get another 17-55 anyway, as I plan to get C100/300, BMCC or Scarlet by summer, but a 17-55 won't fill the need of event photography if my body is the 6D or 5D iii. I'll try the 24-105L as a good compromise and sell it or keep it as a video only lens if I have to.


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## jon_charron (Mar 7, 2013)

neuroanatomist said:


> TrumpetPower! said:
> 
> 
> > One of the regulars here -- sorry, I don't remember which one -- often makes the point that the 24-105 on full frame is superior in every way to the 17-55 on a crop. It's wider and longer, you can get a shallower depth of field, and you get less noise.
> ...



I wonder how that will effect the ability for the 24-105 at f4 to focus quickly on a face in very low light with the 6D? Does the 6D not offer a precision center focus point that will work with this lens at f4??


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## TrumpetPower! (Mar 7, 2013)

neuroanatomist said:


> TrumpetPower! said:
> 
> 
> > True -- assuming, of course, the camera itself has an f/2.8 high precision center AF point. If I remember right, the Rebels at least don't, even if Jon's 7D does....
> ...



Didn't know (obviously). Good to know. Thanks!

...not that I'm likely to shoot with a Rebel any time soon....

b&


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## Drizzt321 (Mar 7, 2013)

*Re: Duplicate APS-C and 17-55 2.8 IS in Full Frame?*



wickidwombat said:


> jon_charron said:
> 
> 
> > Going up to f4 made a huge difference and was not really an option. DOF is not a concern for this type of shooting, especially since flash will punch out the DOF anyway. My concern with the Tamron is well...it's a Tamron,
> ...



The Tamron uncertainty is understandable, but I have used the lens, and it's quite a nice lens, especially when you throw in the price. AF on it moves a small bit slower than many of the rest of the L lenses, but build, optically, IQ, and VC (Tamron's name for IS) are all very good, on part with the vast majority of L lenses.

That said, using a flash I'd say you hardly need any kind of IS unless you're dragging your shutter way slow (which it looks like you're doing), but the subjects you are hitting with the flash will still be in pretty good exposure due to having a relative ton of light being reflected back to the sensor compared to the surroundings. 

So if you're really concerned, go for the Canon 24-70 v2, otherwise I'd rent the Tamron and try it out. You'll find it's quite heavy actually, although I believe the 24-70 v2 is pretty heavy as well.


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## wickidwombat (Mar 7, 2013)

*Re: Duplicate APS-C and 17-55 2.8 IS in Full Frame?*



jon_charron said:


> wickidwombat said:
> 
> 
> > Ummmm I dont quite think you understand the concept of DOF here flash and DOF are two completely mutually exclussive aspects. ie flash has precisely zero effect on DOF. DOF is a function of the lens and sensor the flash simply provide light for the exposure.
> ...



another thing i thought of was do you really need the zoom?
what about the new canon 35mm f2 IS I can see this on a 6D being a pretty killer combo for what you shoot
I tried one out but went for the sigma 1.4 instead as i was after the sharpness over the IS but I can definately see why you want the IS and it still is a really well built lens
I'd have a look at what focal lengths you typically shoot, from those posted they look alot like around about the 35mm range

flash doesnt bring anything into focus though  it just makes in focus objects it lights sharp due to the very high effective shutter speed given by the instantaneous flash burst


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## jon_charron (Mar 7, 2013)

*Re: Duplicate APS-C and 17-55 2.8 IS in Full Frame?*



Drizzt321 said:


> That said, using a flash I'd say you hardly need any kind of IS unless you're dragging your shutter way slow (which it looks like you're doing), but the subjects you are hitting with the flash will still be in pretty good exposure due to having a relative ton of light being reflected back to the sensor compared to the surroundings.
> 
> So if you're really concerned, go for the Canon 24-70 v2, otherwise I'd rent the Tamron and try it out. You'll find it's quite heavy actually, although I believe the 24-70 v2 is pretty heavy as well.



Yes. Dragging the shutter and shooting rear curtain at Events. Using more light is not the answer. I want the ambient to expose and not be affected much by flash and all but very near the lens to stay in motion and be blurry.


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## jon_charron (Mar 7, 2013)

*Re: Duplicate APS-C and 17-55 2.8 IS in Full Frame?*



wickidwombat said:


> another thing i thought of was do you really need the zoom?



Yes. What zoom does in a constant aperture lens like the 17-55 is allow you to set your camera exposure and flash output manually for the room, then use the zoom to frame while trying to maintain the same distance to the subjects you want to capture. You can also fine tune that by how you hold the flash, and in my case, the bounce attachment I use. I'm usually bending it and shaping it with my teeth if I need to widen or intensify light. 

If that doesn't work I move closer or farther or if it's a drastic change, I change the exposure slightly - first by changing the shutter because it's fastest and at my finger tips, and then if necessary, bump the flash a bit up or down. I try not to mess with the ISO and aperture much and need to keep the shutter reasonably show to get the looks I want. When I'm working, this all happens very fast and I can sneak in and out and get candid shots very easily. Even if I need a second shot to adjust, I can usually bounce out before people really start to pose. I don't have any others uploaded but I'll look to see a better example. IS is indeed a MUST. At least for me. I'll see how the ISO plays, but having better ISO and lower noise is something I'll want to take advantage of if possible. It would suck to just crank it up and get what I had before, but I'll take that if it's all I can get.


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## Drizzt321 (Mar 7, 2013)

*Re: Duplicate APS-C and 17-55 2.8 IS in Full Frame?*



jon_charron said:


> Drizzt321 said:
> 
> 
> > That said, using a flash I'd say you hardly need any kind of IS unless you're dragging your shutter way slow (which it looks like you're doing), but the subjects you are hitting with the flash will still be in pretty good exposure due to having a relative ton of light being reflected back to the sensor compared to the surroundings.
> ...



Well, as I said, IS doesn't seem as important for this situation. You're moving the lens anyway, so with IS on it'll attempt to compensate for that.


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## jon_charron (Mar 7, 2013)

*Re: Duplicate APS-C and 17-55 2.8 IS in Full Frame?*



Drizzt321 said:


> jon_charron said:
> 
> 
> > Drizzt321 said:
> ...



Trust me. It's important. The difference is quite remarkable.


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## Drizzt321 (Mar 7, 2013)

*Re: Duplicate APS-C and 17-55 2.8 IS in Full Frame?*



jon_charron said:


> Drizzt321 said:
> 
> 
> > jon_charron said:
> ...



Really? That's interesting. Do you have any comparison shots where you have IS on, and then IS off with similar subjects/exposure/etc? I'd be very interested to see the difference.


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## jrista (Mar 7, 2013)

neuroanatomist said:


> jon_charron said:
> 
> 
> > I crank the ISO up and still can't get the keeper rate as high at 1/1600 and higher using f4 compared f2.8. 2.8 always wins when both have IS and *the ISO is similar stops*. Maybe it's more a focusing issue. I certainly came to know the intricacies of the 7D while I had it and used to kind of irritate the BIF guys with the bigger F4 lenses at times when shooting side by side, especially in the golden hour.
> ...



Wow, great photo! It's amazing that is ISO 6400...that setting is completely unusable on the 7D, even in relatively good light. I was just replying to someone the other day who proclaimed that the notion that small pixels increase noise is a "myth"...I'd love them to see this photo. It kind of proves my point...higher noise with smaller pixels is most certainly not a myth....there just isn't enough light per pixel to compare to something like the 1D X (assuming similar framing, anyway...although even with a center crop on the 1D X and a full frame with the 7D, downsampling won't completely mitigate the higher noise of the 7D's smaller pixels.)

I would actually be curious to know if you pushed ISO even higher, 12800, whether that would saturate the sensor more, and with a little post-process pullback, might actually result in less visible noise...


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## EvillEmperor (Mar 7, 2013)

jrista said:


> neuroanatomist said:
> 
> 
> > jon_charron said:
> ...


It is a great photo, but (with all due respect to Jon) iris noisy, grainy, and soft. I'm not sure how you don't see that.


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## verysimplejason (Mar 7, 2013)

24-70 F2.8 (I/II) or 24-70 F4 or the Tamron version. 24-105 F4 IS is also a nice match.


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## jon_charron (Mar 7, 2013)

EvillEmperor said:


> jrista said:
> 
> 
> > neuroanatomist said:
> ...



That's not my photo. I think it's a 6400 ISO shot from neuroanatomist.

Here is one of mine of a Pelican. This is a very small, fairly low res jpeg uploaded to my blog which resizes and messes with the resolution of the photos. The clean jpeg is MUCH sharper. It was taken with a 7D and a 70-200 2.8 IS L II shot at 200/f2.8 @ 1/1600th I believe and maybe 640 ISO using a Better Beamer.


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## wickidwombat (Mar 7, 2013)

I'm hoping sigma come out with a new 24-70 f2.8 OS to rival the tamron if its built anything like the 35mm f1.4 its gonna be amazing. doesnt help you right now though. at least when sigma release a lens its available within a month or so not a matter of years... canon i'm talking to you!


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## jrista (Mar 7, 2013)

EvillEmperor said:


> jrista said:
> 
> 
> > neuroanatomist said:
> ...



Well, first...the existence of noise doesn't change the fact that the photo is well-executed. It is composed well, the bird's head angle is great, the background is nice. The perch is a bit large...but most of the time you don't really have a choice in that matter. Regardless of the technical factors, its a great photo. When I decide whether I like a photo, I first rate the creative aspects, then the technical aspects. If the bird was out of focus, had the wrong DOF, was significantly noisy (this one is not...it's only moderately noisy), was undesirably under or over exposed, etc. then I'd have problems with it. The only issue with the photo at all that I can see is the background noise, and potentially slightly too much of a crop (which is probably where the slight softness comes from.)

I've never cared for excessive sharpness. I like just a touch of soft...no halos, no jaggies. As for the noise...its ISO 6400... My 7D looks that noisy at ISO 1600, so I find that to be pretty amazing. I do think, however, that it would probably actually look LESS noisy at ISO 12800...maybe even ISO 16000. ETTR is often best done by choosing the slowest shutter possible and necessary aperture, then pushing the histogram as far left as possible with ISO. The closer you get the sensor to maximum saturation the better...and if you can't do that by getting more light on the sensor, the next best option is pushing ISO (which is far better than pushing exposure in post most of the time....the one potential exception, at least on Canon cameras, tends to be the top two ISO settings, which use a downstream post-sensor, pre-ADC amplifier that starts to bring in a lot of color noise.)


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## jon_charron (Mar 7, 2013)

I think the point was to show how good an image can look at ISO 6400. It's the difference in getting a shot and not, but IMO is more of a sports scenario or where the moment is what counts, rather than a nature photo, unless of course it's come rare specimen, rarely photographed. In any case, it's not the type of photographic problem I'm trying to solve and for which I started this thread. Still interesting, but not very relevant for me outside of comparing it to a ISO 6400 image from the 7D.


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## heptagon (Mar 7, 2013)

27.2-88 f/4.48 would be equivalent for taking identical pictures.


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## Radiating (Mar 7, 2013)

I think you completely misunderstand how full frame works.

A 17-55mm f/2.8 IS lens, will deliver identical geometry to a *27-88mm f/4.48 IS *lens on full frame.

depth of field is a function of geometry. 






So as the iris or aperture opens up more it allows more light in, but because that light is light that is coming at a higher incident angle it is focused over a greater area if it is behind or infront of the focal plane. So therefore you have a shallower depth of field. See how the red point is larger and therefore will be blurred on the open aperture example?

Here's another example:







People have been misled with crop to full frame conversions for years.

The "35mm equivalent" is what is really important and nothing else. Your images on 35mm equivalent will always look the same no matter what.

From a physics perspective the "35mm equivalent" is capturing identical information. What really matters is the geometry of the light hitting the sensor, and with 35mm equivalent the geometry will always be the same for a given equivalence. Not only that but your flash settings etc will be identical:


Going back to the 35mm equivalent discussion, consider this:

On 7D compared the the 5D Mark III


The sensor is 1.6 x 1.6 times smaller.

35mm equivalent aperture - Multiply F-Number by (1.6 ) . (an f stop is a base 2 log, so even though we have 1.6x1.6 times as much light we take the square root, which is 1.6 to multiply the F number by. (example 2.8 x 1.6 = 4.48, 4.0 x 1.6 = 6.4))

35mm equivalent focal length - Multiply by 1.6

35mm equivalent ISO or light sensitivity - Multiply by (1.6 x 1.6) (bet you haven't heard of that, but if you do the math the 7D's sensor amplifies the signal 1.6x1.6 times more at a given ISO than the 5D3, so even if both say ISO 800, ISO 800 on the 7D is multiplying the pixels the same as ISO 2000 on the 5D Mark III)


The point is that people are often misled by manufacturers changing the geometry of a camera system, particularly putting in small sensors and then claiming otherwise impressive performance numbers which are incredibly misleading because you are measuring them on a different scale.

It's like saying:

I have a million dollars, and then failing to mention these are Zimbabwe dollars worth $20 not, American dollars.

Yes aperture ISO and focal length are fixed numbers, but so are monetary figures, and the most important thing even the most basic dealing of currency has is WHAT currency you're dealing with, and 99% of people require an "equivalent" frame of refference to understand foreign currency or need to do a conversion. Likewise with cameras, geometry (type of currency) is the most important thing when dealing with the performance of a camera system, and the first thing anyone needs to do is bring up a conversion to the local frame of reference, APS-C 35mm, whatever.

To respond to your concern though, there is NO benefit to a 1 stop faster aperture on APS-C sensor vs full frame because they (more than) cancel each other out. You don't stop action any quicker at all, whatsoever, because remember the ISO is skewed too, so all you're doing is just turning up the ISO sensitivity in a roundabout way by. You have been misled into thinking there is anything else going on.

Anyways, get the 24-105mm f/4.0, it will be much better in every way than your 27-88mm f/4.48 IS equivalent lens. Also remember ISO 800 on the 7D is equivalent to ISO 2000 on the 5DIII.

So in other words theoretically a Crop set to:

#1. 17mm - f/2.8 - ISO 800 - 1/50th - with 1/4 flash
#2. 55mm - f/2.8 - ISO 800 - 1/50th - with 1/2 flash

Will produce a 100% identical image with no difference in exposure, lighting, depth of field, field of view or composition when compared to a full frame set to:

#1. 27mm - f/4.48 - ISO 2048 - 1/50th - with 1/4 flash
#2. 88mm - f/4.48 - ISO 2048 - 1/50th - with 1/2 flash

Literally no difference.

Now of course each lens will have it's own characteristics and each body will likewise have it's own, and the full frame with the 24-105mm will delivery much better image quality as will any full frame body, but if both bodies and lenses were theoretically perfect and had the same resolution these settings would deliver the exact same with completely identical pixels.


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## jon_charron (Mar 7, 2013)

Radiating said:


> I think you completely misunderstand how full frame works.



Hi Radiating. I appreciate the very thorough explanation! 

I do not "completely misunderstand how full frame works" in that I do understand the relationship of DOF when it comes to just DOF...what is in focus with the same lens, crop vs. FF. 

This is most apparent in video, and why FF and the 5D II changed the film world - the ability to blow out backgrounds and create that super thin DOF "look." I have also experienced focus pullers on set having problems with DOF that was too thin, and resulting footage that looked properly focus on the lcd screen but turned out to be soft when viewed at 1080p. Disaster. This is why I would always use the 7D over the 5D. It was more forgiving for focus if the puller was a bit out or the talent moved or swayed or slightly missed the mark, and at f2.8 still allowed shooting in fairly low light. 

OTOH, now I'm more experienced with pulling focus myself and in selecting DP's, and plan (hopefully tomorrow) to buy a FF body instead of another crop. Having 2.8 and the option to go with shallow DOF compared to what is available at f4 would be nice. Suffice it to say that I would still prefer a 2.8 IS in a comparable range if it was available. If I want to buy a crop body or dedicated video rig later (like a c100/c300, BMCC or Scarlet), having the 2.8 would also be desirable to get the DOF down and keep the light transmission up. Naturally, IS for video is also a huge benefit in all ways. But I digress. This was a photography question, and I recognize that at some point, I may need to buy a 17-55 2.8 for the crop sensor dedicated rig I buy that will be s35. That lens cannot be used on the 6D.

The rest of the info about light and angles and stuff is all new to me, and I thank you for that. I'm going to read it one more time to let it sink in a bit better


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## heptagon (Mar 7, 2013)

@Radiating

There is one difference though. Bigger pixels mean MORE noise. That is because of the larger surface and volume of the pixels the thermal and readout noise will increase. Therefore if high DOF is a requirement a smaller sensor will likely be the winner considering image quality. Especially when small sensors allow back illumination with very high quantum efficiencies. Small sensors hit the diffraction limit though which will limit their resolution.


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## xhermitdashx (Mar 7, 2013)

I believe the best combo for you is actually the tamron 24-70 vc with 6d/5d (depending on your budget)
reason for the tamron: GREAT vc, works extremely well
Rather smooth focus rings, obviously not as smooth as canon's offer, but i think its enough.
of course, f/2.8
CHEAP PRICE! nearly half of canons 24-70 ii


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