# FF Sharper than crop?



## Robboesan (Feb 27, 2014)

Hey guys!
So I noticed on the digital-picture website iq comparison tool that FF seemed always sharper than a crop sensor. 
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=486&Camera=736&Sample=0&FLI=0&API=0&LensComp=486&CameraComp=0&FLIComp=0&APIComp=0
Are there any physical explanations for this phenomenon? 
I am new to this so....


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## Marsu42 (Feb 27, 2014)

Robboesan said:


> Are there any physical explanations for this phenomenon?



The main reason - next to various others that also may have some role - the "crop" sensor only uses the center part of the lens. If the edges of the lens are crappy (old/cheap lenses or some ultra-wide) that can be an advantage, but usually it isn't because the 20mp of a 70d sensor are illuminated through less glass than the 20mp of a 6d. If this central lens part is not sharp "enough" this results in the effect you observed... but often it's only visible in test charts, not in real life, and then only if shot wide open and not stopped down.


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## Don Haines (Feb 27, 2014)

Marsu42 said:


> Robboesan said:
> 
> 
> > Are there any physical explanations for this phenomenon?
> ...


and then there is the strength of the AA filter in your particular camera......


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## neuroanatomist (Feb 27, 2014)

Robboesan said:


> Are there any physical explanations for this phenomenon?



Enlargement. When comparing output of equivalent dimensions, the image from the smaller sensor needs to be enlarged more, and that results in a relatively softer image.


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## dtaylor (Feb 27, 2014)

The formal answer is that with any lens detail contrast drops as resolution increases. This relationship is illustrated by the lens MTF curve. A lens has more contrast at 10 lpmm then at 20 lpmm. When you frame a scene onto a smaller sensor, the details occur at a higher lpmm frequency and therefore have less contrast.

However, at low to mid ISO it's a meaningless difference because the contrast can easily be restored in post processing, whether in a tool like Photoshop or in camera using the sharpness setting. Detail contrast is not an unlimited good, and at ISO 800 and below it's trivial to make an APS-C file as sharp as an optimally processed FF file. At high ISO FF has a true sharpness advantage because when you apply extra sharpening to the ASP-C file you emphasize noise that's not in the FF file.


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## dtaylor (Feb 27, 2014)

neuroanatomist said:


> Robboesan said:
> 
> 
> > Are there any physical explanations for this phenomenon?
> ...



In the darkroom optical enlargement impacts sharpness again. But this isn't an issue with digital capture. The sharpness difference observed out of camera between APS-C and FF exists at the sensor at the moment of capture and is visible at 100% / pixel view. 

Sometimes interpolation to screen resolutions impacts sharpness on its own. But so long as you have sufficient image resolution for the desired print size, digital interpolation or enlargement for printing rarely if ever impacts sharpness today.


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## 2n10 (Feb 27, 2014)

Robboesan said:


> Hey guys!
> So I noticed on the digital-picture website iq comparison tool that FF seemed always sharper than a crop sensor.
> http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=486&Camera=736&Sample=0&FLI=0&API=0&LensComp=486&CameraComp=0&FLIComp=0&APIComp=0
> Are there any physical explanations for this phenomenon?
> I am new to this so....



I believe he also frames the shot the same so you are shooting from a greater distance with a crop camera.


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## Rocky (Feb 28, 2014)

The resolution of the lens used in the Crop sensor needed to have 1.5 time more resolution than the one used in the FF to give us the same sharpness. We are not even talking about diffraction limiting yet.


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## candc (Feb 28, 2014)

A lens has to be really sharp to stand up on a crop body shooting test charts. 

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=458&Camera=845&Sample=0&FLI=0&API=0&LensComp=458&CameraComp=0&FLIComp=0&APIComp=0

This case looks pretty similar


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## pdirestajr (Feb 28, 2014)

There must be something in the FF vs APS-C water this week, this is like the 3rd thread on this subject!

Maybe it means the 7D mkII is gonna be announced soon and rock the universe!!!!


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## candc (Feb 28, 2014)

pdirestajr said:


> There must be something in the FF vs APS-C water this week, this is like the 3rd thread on this subject!
> 
> Maybe it means the 7D mkII is gonna be announced soon and rock the universe!!!!



Every thread seems to end up on this topic.


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## Solar Eagle (Feb 28, 2014)

The main reason full frame is sharper is because its projecting a larger image circle, and there is always going to more detail possible in a physically larger area than there will be in a physically smaller area. Plus the full frame images are sharper because full frame pixels are much larger. Bigger pixels always give better pixel level detail. 

Also keep in mind lenses that are optimized to project a full frame image circle are spreading the available detail out more, and using a full frame lens on crop frame means you are discarding a lot of what the lens is capturing, since you are only using the center part of whats being projected. This has the effect of making your full frame lenses longer on crop compared to full frame, because you have to step back in order to shrink the projected image so its fits one crop sensor. 

Lenses optimized for crop frame focus the available detail captured by the lens into a smaller area, so there is potential for greater resolution within that area compared to spreading the image out more like full frame lenses do. Take a look at the 22mm lens for EOS M if you want to see a very sharp lens optimized for crop sensor. Thats one of the sharpest crop frame lenses you will find in the digital picture test charts.


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## CropFactor (Feb 28, 2014)

Read this :
http://www.dxomark.com/Reviews/Looking-for-new-photo-gear-DxOMark-s-Perceptual-Megapixel-can-help-you

For the pixel peepers, it's rather worrying the amount of resolution lost in cropped systems.

There is very little to gain by sticking an L lens on a crop body. 

(Watch me get mauled to death for this...)


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## J.R. (Feb 28, 2014)

CropFactor said:


> Read this :
> http://www.dxomark.com/Reviews/Looking-for-new-photo-gear-DxOMark-s-Perceptual-Megapixel-can-help-you
> 
> For the pixel peepers, it's rather worrying the amount of resolution lost in cropped systems.
> ...



I wonder why you say that. As far as I have noticed, FF + average lenses = crop with better lenses.


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## CropFactor (Feb 28, 2014)

J.R. said:


> CropFactor said:
> 
> 
> > Read this :
> ...



That is possible yes. But why would you cripple your FF with an average lens?

What I'm saying is the difference is resolution (sharpness) between 'L' and 'non-L' on a crop body isn't that significant.

For example you won't gain 8MP in overall resolution by jumping from a 12MP 450D to a 20MP 70D (crop of course). You might gain 2-4mp. There are losses in any given system. More so for crop.

Even if a crop body makes use of the so called sweet spot of a lens, you just won't get the resolution you expect you would from a high MP crop body 

If you want real gain in sharpness, go with FF + L


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## ecka (Feb 28, 2014)

> FF Sharper than crop?



Yes, it is, because crop is cropped .


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## Marsu42 (Feb 28, 2014)

CropFactor said:


> There is very little to gain by sticking an L lens on a crop body.



So what ef-s tele lenses do you use (hint: there are none), or what non-L tele lenses do you recommend at a lower price than for example the 70-300L with the same sturdiness and weather sealing?


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## CropFactor (Feb 28, 2014)

Can we possibly say this :

Lets assume a 20MP crop canon here....

20/1.6 = 12.5

12.5 being the maximum MP you could possibly hope to get.

Add then loss from the AA filter, lens quality and any other attached elements.

Lets say you can realistically get 8 - 11MP from a 20MP crop.

Does this sound far fetched or not? ???


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## CropFactor (Feb 28, 2014)

Marsu42 said:


> CropFactor said:
> 
> 
> > There is very little to gain by sticking an L lens on a crop body.
> ...



We are not debating functionality but rather sharpness 

I was referring to the difference in sharpness (detail) for "CR + Non L" vs "CR + L".

Compare "FF + L" vs "CR + L" even if both bodies are 20MP, the FF will win when it comes to detail.


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## ecka (Feb 28, 2014)

Marsu42 said:


> CropFactor said:
> 
> 
> > There is very little to gain by sticking an L lens on a crop body.
> ...



Actually, there is one pretty decent EF-S tele lens EF-S 55-250mm f/4-5.6 IS STM lens.


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## Marsu42 (Feb 28, 2014)

CropFactor said:


> We are not debating functionality but rather sharpness



But then you're missing the point of L lenses - they're not L because only they excel in sharpness, but as a combination of different factors ... if looking at sharpness alone, there are quite few L duds wide open uwa or older L lenses like 35L vs. newer 3rd party. The L glass is also supposed to have good color rendition which might be more important to some than test-chart pixel counting.


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## CropFactor (Feb 28, 2014)

Marsu42 said:


> CropFactor said:
> 
> 
> > We are not debating functionality but rather sharpness
> ...



The question is : FF Sharper than crop?

Answer : Yes it is. Bigger sensors capture more detail even when compared to a crop with the same MP.
(6D vs 70D = no contest, 6D wins)

Added : To get the most from an FF, stick an L on it. (Look, even non L primes are amazing)

Again ill say, the difference in sharpness between CR + L and CR + Non L is marginal at best.

So with everything said, if you have a cropped body and you want more detail in your photos, go for a FF body.


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## CarlTN (Feb 28, 2014)

dtaylor said:


> The formal answer is that with any lens detail contrast drops as resolution increases. This relationship is illustrated by the lens MTF curve. A lens has more contrast at 10 lpmm then at 20 lpmm. When you frame a scene onto a smaller sensor, the details occur at a higher lpmm frequency and therefore have less contrast.
> 
> However, at low to mid ISO it's a meaningless difference because the contrast can easily be restored in post processing, whether in a tool like Photoshop or in camera using the sharpness setting. Detail contrast is not an unlimited good, and at ISO 800 and below it's trivial to make an APS-C file as sharp as an optimally processed FF file. At high ISO FF has a true sharpness advantage because when you apply extra sharpening to the ASP-C file you emphasize noise that's not in the FF file.



+1, well said! 

Full frame is generally sharper than crop, because the pixels are larger, thus the lens need not be as sharp to achieve a desired level of sharpness.

The link to the EF 200 f/2L comparison is interesting, because it is showing the border and corner resolution inferior on the 70D, to that of the 1Ds3, yet the center resolution appears identical. This alone should show you that the difference here, is that the 1Ds3's pixels are so much larger than the 70D's, that the lens's loss of "sharpness" towards the full frame borders, is hardly noticed by those larger pixels. Yet the 70D is finding the loss halfway to those borders, within its own..."crop circle"! 

This is why I have said (and got pounced on for it), that a future 50+ MP full frame camera, is rarely if ever going to fully resolve detail on all of its pixels on most every lens there is (if not actually every one, even perhaps including the Zeiss Otus...especially if it's more like a 60+ MP full frame sensor). The reason being that you would see unbelievable softness at the pixel level, as you get closer to the full frame borders and corners (especially on even such a fine "big white" as the 200 f/2, shot wide open). I've rented this lens briefly, and I liked it more than every other lens I've tried or owned...so I am not biased against it whatsoever. I frankly feel it has the kind of color rendition that no other lens in the world has...almost everything about it was as close to perfect as I could ask for.

Here is one of my favorite images that I shot with it. It's not full size, because I try not to show those. Camera was the 50D.


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## verysimplejason (Feb 28, 2014)

CropFactor said:


> If you want real gain in sharpness, go with FF + L



L? It's also do-able on most primes.


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## dtaylor (Feb 28, 2014)

Rocky said:


> The resolution of the lens used in the Crop sensor needed to have 1.5 time more resolution than the one used in the FF to give us the same sharpness.



This is false. Resolution and detail contrast (sharpness) are two related but separate things. The measured resolution difference (in lpmm) between FF and APS-C sensors of comparable pixel counts is small as good lenses still comfortably out resolve sensors at MTF10. Adding more pixels to the APS-C sensor would not alter the lens MTF curve. The loss of detail contrast happens in the lens, not on the sensor. (Assuming AA filters of equal strength.)



CropFactor said:


> Read this :



I would rather watch paint dry then read DxO theories.



> For the pixel peepers, it's rather worrying the amount of resolution lost in cropped systems.



DPReview measured the 5D2's resolution to 2800/3300 (absolute/extinction). The 7D was measured to 2500/3100. The difference is smaller then the difference in sensor pixel count. (So much for DxO theories.)



> There is very little to gain by sticking an L lens on a crop body.



Apparently you've never actually tried this. FYI, I can see the difference out of camera between the 70-200 f/4L and 70-200 f/4L IS on a 7D. The difference between either L lens and a consumer zoom on the same body is quite large. (The L vs L differences probably wouldn't survive post processing, but the L vs non-L differences definitely would.)



CropFactor said:


> For example you won't gain 8MP in overall resolution by jumping from a 12MP 450D to a 20MP 70D (crop of course).



You will gain exactly 8 MP because MP is a measure of the number of photo sites on the sensor. The fact that DxO plays fast and loose with definitions and creates meaningless ones like "perceptual megapixels" is the first indication that they are a pseudo-science site.

Your percentage gain in image lpmm will not be equal to the gain in MP because there are losses. But the losses are nearly identical for a 12-20 MP jump in the 35mm format.



CropFactor said:


> Can we possibly say this :
> Lets assume a 20MP crop canon here....
> 20/1.6 = 12.5
> 12.5 being the maximum MP you could possibly hope to get.



No we can't say that. Strictly speaking that is absurd because MP always refers to the number of photo sites on the sensor. I know what you are trying to say, but we can't say it even with correct terminology because all observations are to the contrary (see below).



> Answer : Yes it is. Bigger sensors capture more detail even when compared to a crop with the same MP. (6D vs 70D = no contest, 6D wins)



Detail != sharpness.

For sharpness, I agree that a 6D will be sharper out of camera all other factors being equal. And I'll add that the difference will not survive post processing unless the images were made above ISO 800.

For detail, Imaging Resource has measured and published the resolutions of both, and they are nearly identical. 2400/3400 for the 6D and 2500/3200 for the 70D.


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## dtaylor (Feb 28, 2014)

CarlTN said:


> This is why I have said (and got pounced on for it), that a future 50+ MP full frame camera, is rarely if ever going to fully resolve detail on all of its pixels on most every lens there is...



I wouldn't "pounce" on you for this, but I would disagree. If we were to scale up current APS-C densities they would equal 45 MP or more on FF. The number of lenses and aperture combinations that yield excellent detail and sharpness on my 7D and M are quite large actually. Granted it's more challenging to hold that across the frame on 35mm, but I don't doubt that a 50 MP FF body would prove excellent with good glass and a tripod or IS. I think we would be looking at 75-100 MP before there would be hardly any lenses or apertures that benefit.



> Here is one of my favorite images that I shot with it. It's not full size, because I try not to show those. Camera was the 50D.



Beautiful.


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## ecka (Feb 28, 2014)

dtaylor said:


> CarlTN said:
> 
> 
> > This is why I have said (and got pounced on for it), that a future 50+ MP full frame camera, is rarely if ever going to fully resolve detail on all of its pixels on most every lens there is...
> ...



I think that "excellent detail and sharpness" is a matter of opinion. I thought my 7D+Sigma 50/1.4 was excellent, until I tried 5D2+50/1.8'II (I hated the build, pentagon aperture and AF noise, but it was _*SHARP!*_). FF wins thanks to either bigger pixels or more of them.


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## jeffa4444 (Feb 28, 2014)

Real estate will always win out why do people think fashion photographer shoot with medium format.


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## dtaylor (Feb 28, 2014)

ecka said:


> I think that "excellent detail and sharpness" is a matter of opinion. I thought my 7D+Sigma 50/1.4 was excellent, until I tried 5D2+50/1.8'II (I hated the build, pentagon aperture and AF noise, but it was _*SHARP!*_). FF wins thanks to either bigger pixels or more of them.



I'm going to be blunt because I've shot both combinations (owned both lenses at one time, now just the Sigma): at low ISO and wide apertures, if your final 7D+Sigma file doesn't look better then your final 5D2+NiftyFifty file something is wrong.


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## ecka (Mar 1, 2014)

dtaylor said:


> ecka said:
> 
> 
> > I think that "excellent detail and sharpness" is a matter of opinion. I thought my 7D+Sigma 50/1.4 was excellent, until I tried 5D2+50/1.8'II (I hated the build, pentagon aperture and AF noise, but it was _*SHARP!*_). FF wins thanks to either bigger pixels or more of them.
> ...



By _*SHARP!*_ I mean f/2.8+ sharp . Sigma 50/1.4 produces much nicer bokeh (I think it is one of the best 50s), but I don't think it is sharper wide open on crop, than 50/1.8'II on FF. However, sometimes wide open images from 50/1.8'II are a bit dreamy with glowing high contrast edges.


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## CarlTN (Mar 1, 2014)

dtaylor said:


> CarlTN said:
> 
> 
> > This is why I have said (and got pounced on for it), that a future 50+ MP full frame camera, is rarely if ever going to fully resolve detail on all of its pixels on most every lens there is...
> ...



Thanks very much! I still think I have to disagree with you though. There aren't that many lenses that are sharper than the 200 f/2L, but yet the 70D can't use but about half its pixels to resolve detail through it (at least when wide open at f/2). And the 70D is equal to the middle of about a 50 MP full frame's...frame. I'm not saying you couldn't appreciate the sharpness of the world's best lenses with such full frame sensors...it's just that you could only appreciate it in a small part of the center at wider apertures, and perhaps up to maybe 65% of the sensor area when closed to optimum arperture (especially if we go to 60+ MP).

When you discuss how sharp your results have been with an 18 MP crop sensor, you're forgetting just how much softer the lens becomes once you go larger than that sensor, it seems to me. Discussing the current 22MP 5D3 sensor, has nothing to do with what a 50MP sensor would look like on the same lens.

This surely is one reason why Canon has expressed interest in medium format. I suspect that 10 years from now, medium format will be what we are all using, or beginning to use. And full frame digital cameras will be priced like the Rebels of today (adjusted for inflation of course). But this assumes we will still have a currency, or even a civilization then, and there are no guarantees of that.


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