# Full Frame Sharper Than Crop?



## libertyranger (Oct 19, 2012)

So I've been doing some research and comparing different lenses on The Digital Picture's ISO comparison tool. What I am seeing is that the the same lens on both full frame and crop cameras shows a sharper image on the full frame camera. According to Ken Rockwell, he states that full frame will always be sharper. I know people don't like quoting him much, but from what I see, he appears to be right. 

Here are a couple examples...

50mm 1.4
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=115&Camera=453&Sample=0&FLI=0&API=4&LensComp=115&CameraComp=736&SampleComp=0&FLIComp=0&APIComp=3

85 1.8
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=106&Camera=453&Sample=0&FLI=0&API=2&LensComp=106&CameraComp=736&SampleComp=0&FLIComp=0&APIComp=2

Is there something I'm missing here? Is the difference between the two cameras making a difference, or does full frame generally produce sharper results than crop using the same lens?


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## neuroanatomist (Oct 19, 2012)

FF will deliver sharper results than crop in a situation like this one, where with the same lens the subject is shot from a greater distance with the APS-C camera. If the test was designed such that the camera-to-target distance was the same, and the target filled the APS-C frame but the FF image had to be cropped down by 1.6x, the APS-C image would be a little bit sharper.

But charts aside, I find that FF images are generally better than APS-C, for many reasons.


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## GuyF (Oct 19, 2012)

I suspect it may simply come down to the size of the photosites on a crop sensor. They tend to be smaller than those on full-frame sensor and thus the laws of physics and diffraction come in to play sooner on a crop sensor.

For a fuller and more in-depth answer just hang on, I see our friend Neuro on the horizon with his usual top-notch explanations for the witchcraft that is optical physics. 

Pah! Just as I type this, there he comes!


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## sandymandy (Oct 19, 2012)

I think FF is always nicer because the noise is less so more details are revealed even its not much.


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## libertyranger (Oct 19, 2012)

neuroanatomist said:


> FF will deliver sharper results than crop in a situation like this one, where with the same lens the subject is shot from a greater distance with the APS-C camera. If the test was designed such that the camera-to-target distance was the same, and the target filled the APS-C frame but the FF image had to be cropped down by 1.6x, the APS-C image would be a little bit sharper.
> 
> But charts aside, I find that FF images are generally better than APS-C, for many reasons.



Thanks Neuro. I always look forward to your response on technical questions. I've been doing some portrait work as of late and given the same framing between the two formate, full frame would be the way to go for sharper images


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## neuroanatomist (Oct 19, 2012)

libertyranger said:


> TI've been doing some portrait work as of late and given the same framing between the two formate, full frame would be the way to go for sharper images



Indeed. Even from the same distance with a different lens. I've compared the 7D + 85L II to the 5DII + 135L, the latter wins.


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## darrellrhodesmiller (Oct 19, 2012)

i just went from a 7D to a 5D mk III. Both are incredibly sharp cameras when you have proper exposure and shutter speed. The difference i see is that the 5D mk III is much less noisy.. so it seems sharper in high ISO situations. 

i will also say i know alot of people when they move from shooting JPG to RAW dont realize that they have to sharpen their images in post. With JPG's its done in camera, but with RAW you have to do the sharpening. it makes a difference.


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## PavelR (Oct 19, 2012)

I think that the main difference is in in/correct focus, DoF and overal chip technology used and of course the mpx density in 100% magnification, which reveal all details of used glass.
If I've changed, in the first link comparison of 50/1.4, the camera from 60d to 1dsII, center still looks much softer than real life photo...


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## Policar (Oct 19, 2012)

Lenses will always perform 1.6x better in the center in FF. Corners might be worse. Since few people outresolve the sensor in everyday shooting at that 1.6x MTF boost is for all frequencies, I'd think FF would look much sharper for most.


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## 7enderbender (Oct 19, 2012)

I find sharpness to be over-rated. My 8MP PowerShot P&S from several years ago is _sharp_. That's not really a big deal. Where bigger is better is when it come to NOT sharp.


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## bkorcel (Oct 19, 2012)

My opinion is that any comparison between full frame and crop cameras is to use the same lens with the same subject and distance.

Further, my opinion using a 7D and 5D3 is that the 5D3 wins given all else being the same. The reason mainly is that you get some forgiveness with the increase in pixel density allowing you to crop if needed as well as the decrease in effective noise levels requiring less post processing artifacts.

Also one of the benefits (particularly with wildlife photography) is that the FF over the crop allows me to be more flexible when using primes as the recorded angle of view is slightly wider. Even if I have to crop the image slightly, I don't lose any IQ for the size I usually print to which is around 12 x 18"


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## Quasimodo (Oct 19, 2012)

GuyF said:


> I suspect it may simply come down to the size of the photosites on a crop sensor. They tend to be smaller than those on full-frame sensor and thus the laws of physics and diffraction come in to play sooner on a crop sensor.
> 
> For a fuller and more in-depth answer just hang on, I see our friend Neuro on the horizon with his usual top-notch explanations for the witchcraft that is optical physics.
> 
> Pah! Just as I type this, there he comes!



I have a question also. Diffraction. I have read about it, and there are several places that warns against closing the lens too much (some say you should not go to F22, but stay at F16 due to diffraction. Does anyone have a practical example on how this would alter a picture, besides a theoretical argument? Otherwise, when shooting landscape for instance, why would one not go minimum aperture all the time, given that you control the other factors?


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## RLPhoto (Oct 19, 2012)

The larger the format of Film, The less critical it is on the lens you put in-front of it.


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## dtaylor (Oct 19, 2012)

You have to remember that lens resolution is not a single number. It's an MTF curve describing detail contrast for a given resolution. The higher the resolution, the lower the detail contrast. For a given number of megapixels, crop sensors use smaller pixels. That means detail is recorded at a lower point on the lens MTF curve...lower contrast...vs. a FF sensor.

So yes, FF DSLRs provide sharper images out of camera.

However, at low to mid ISO this is a non issue. All DSLR images (or at least all DSLR images with AA filters) benefit from sharpening, and most benefit from local contrast enhancement. You're going to sharpen the files either way. With crop you just sharpen more in your RAW converter or PS. If you want out of camera JPEGs, you turn up the camera sharpening a little more.

At high ISO this works against crop bodies because the sharpening enhances the noise. And it's at high ISO that I think FF really distinguishes itself. But for all the talk about FF vs. crop, at low to mid ISO there really isn't much difference. Nothing that would stand out even in a 24" print. (Even 4/3rds is capable of matching crop/FF with the same MP count at low ISO.)

Diffraction softens the image. At f/22 (FF) and f/16 (crop) the impact is enough that you cannot fully compensate with sharpening in post. I do not use f/22 on FF, and do not use f/16 on crop, except in very special circumstances. With landscape shots I try to use hyperfocal focusing and the largest aperture possible while still retaining the DoF I want. LiveView is great for evaluating this. 

Note that diffraction does not impact any format more than any other for a given FoV and DoF.


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## Act444 (Oct 19, 2012)

I can only speak from my personal experience, but as far as I can see the answer is a resounding YES, IT IS.

I've got a 5DIII and a 60D. Indoors, the 5DIII totally crushes the 60D when it comes to sharpness & detail capture, even with the same lens. The 60D images tend to have a rough quality to them, even at reasonably low ISOs, and the 5D is just much cleaner. It becomes indistinguishable from 60D only from ISO 6400 up- but then again you wouldn't even USE the 60D at those ISOs...

Haven't tested outdoors in great lighting yet, but I'd think the difference might be less obvious there.


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## GuyF (Oct 20, 2012)

Quasimodo said:


> GuyF said:
> 
> 
> > I suspect it may simply come down to the size of the photosites on a crop sensor. They tend to be smaller than those on full-frame sensor and thus the laws of physics and diffraction come in to play sooner on a crop sensor.
> ...




Whilst it was only speculation on my part, check out the examples here:

http://www.luminous-landscape.com/tutorials/understanding-series/u-diffraction.shtml

http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

Also the table near the top of the page here http://www.the-digital-picture.com/Reviews/Canon-EOS-7D-Digital-SLR-Camera-Review.aspx gives values for apertures where diffraction might start to creep in. Note that they say it may not be visible depending on what size and how you view the image.


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## Quasimodo (Oct 20, 2012)

GuyF said:


> Quasimodo said:
> 
> 
> > GuyF said:
> ...



Ok, thanks. I will look at them


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## ahsanford (Oct 22, 2012)

@Quasimodo, regarding diffraction:

Depending on the lens, you see a resolution/sharpness 'sweet spot' (usually between F/4 and F/8 or so) where the sharpness is optimal. As I understand it, when you stop down beyond that, you are effectively trading a little bit of sharpness to extend your depth of field.

http://www.photozone.de/canon_eos_ff has this well documented if you are a data guy. Grab any lens and see it's 'analysis / resolution' section to see the drop off in sharpness with narrow apertures -- it happens to all glass, apparently.


There is also a body/sensor related issue on how well stopped down images are handled. From Bryan Carnathan's http://www.the-digital-picture.com, he states:

_"* DLA (Diffraction Limited Aperture) is the result of a mathematical formula that approximates the aperture where diffraction begins to visibly affect image sharpness at the pixel level. Diffraction at the DLA is only barely visible when viewed at full-size (100%, 1 pixel = 1 pixel) on a display or output to a very large print. As sensor pixel density increases, the narrowest aperture we can use to get perfectly pixel sharp images gets wider.

DLA does not mean that narrower apertures should not be used - it is simply the point where image sharpness begins to be compromised for increased DOF and longer exposures. And, higher resolution sensors generally continue to deliver more detail well beyond the DLA than lower resolution sensors - until the "Diffraction Cutoff Frequency" is reached (a much narrower aperture). The progression from sharp the soft is not an abrupt one - and the change from immediately prior models to new models is usually not dramatic." _


Getting back to real world shooting with all this... I had a bad habit with my landscapes of maximally stopping my lens down (F/22, F/25, etc.) simply _because I could_ -- I was on a tripod, I had more light than I needed, etc. When I was shooting, say, a far off mountain range with nothing in the foreground, I was simply throwing some sharpness away by stopping down so far.

Perhaps this is what gets people into using hyperfocal tables (e.g. http://www.dofmaster.com/dofjs.html) to choose the right aperture for large DOF work, but as a novice, I can't speak to that. I defer to the pros in this forum to speak to that.

- A


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## JBeckwith (Oct 23, 2012)

I don't have any technical knowledge about this, but I can certainly express my opinion. When I upgraded from crop to FF I noticed a "change" in my pictures. Yes they became sharper, but that could have been due to a lens upgrade as well. FF images seem to have a different feel to them. I don't really know how to explain it, but I believe anyone who has gone from crop to FF will probably be able to relate.


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## crasher8 (Oct 23, 2012)

You can throw all the science at this and yadda yadda yadda all you want but for someone who has just made the leap, the answer is YES.


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## LetTheRightLensIn (Oct 23, 2012)

libertyranger said:


> So I've been doing some research and comparing different lenses on The Digital Picture's ISO comparison tool. What I am seeing is that the the same lens on both full frame and crop cameras shows a sharper image on the full frame camera. According to Ken Rockwell, he states that full frame will always be sharper. I know people don't like quoting him much, but from what I see, he appears to be right.



FF is sharper than APS-C using the same lens at the same aperture at the 100% view if it has lower photosite density than the APS-C camera (very often this is the case) and the AA filters are not radically different between the two.


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## Dylan777 (Oct 23, 2012)

I don't know sharper or not with FF, the #1 reason I went with FF is because I want to take pictures under low light - without flash.

I was happy with 5D II. I'm happier with 5D III now. I will be VERY HAPPY with 1D X in the future ;D


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## AlanF (Oct 23, 2012)

Here are some simple calculations and experiments that show the 7D does give extra reach of about 45% over a 5D III. Theory tells us that in order to resolve two parallel lines, their images should be at least 2 pixels apart. On a 7D, which has a 4.3 µ pixel, that would be 8.6 µ apart and on a 5D III, with a 6.25 µ pixel, that would be 12.5 µ apart. For an object at a distance v, which is much further away than the focal length of the lens f, the size of the image is given by the size of the object times f/v. For the same lens on a 7D and the 5D III with a lens aperture wide enough so it is not diffraction limited (wider than f/6.9 for the 7D, 10.1 for the 5D III), the sizes of images on both sensors will be the same for the same distances but the image will span more pixels on the 7D. In order to cover two pixels, the object will be 1.45 times further away for the 7D. I did some experiments to test the resolution of the 7D fitted with an f/2.8 300mm II and 2xteleconverter to give f = 600mm and f/5.6. I photographed a feather whose barbs (middle right, below halfway) in the photo were approximately parallel lines separated by 0.27 mm or 0.31 mm (middle right, above halfway). At 5 m distance, nearly all the barbs, including others that were not parallel to the rows or columns of the sensors were very clearly resolved the calculated distances in the image were 16.1 and 18.7 µ, respectively, for the lower and upper sets. At 9 m separation, the barbs were still clearly resolvable, with calculated image sizes of 8.9 and 10.4 µ, just above the supposed limit for resolution of 8.6 µ. The barbs were just resolved at 12 m, with image sizes of 6.7 and 7.8 µ respectively. The images became unresolvable between 14 and 16 m. My calculations of height of image are reliable within 3 percent since the same calculations gave a pixel size of 4.4 µ for the 4.3 µ pixel. So, despite all its supposed limitations, the 7D resolves images at the closest theoretical limits. In order to have the clean separation seen at 9 m on a 7D, the feather would have to be at 6.2 m from the 5D. The transition of just being resolvable at 12 m from the 7D would be 8.3 m from the 5D, and the complete loss at 14-15 m from the 7D would be 9.6-10.7 m on the 5D. It doesn’t matter how superior the 5D III is than the 7D, the laws of optics and information theory dictate that at 9 m you can resolve the barbs of feathers on a 7 D but you see a blur with the 5D using a 600mm lens.


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## neuroanatomist (Oct 23, 2012)

Thanks, Alan. 

I wonder, though - were you shooting at ISO 100? Many times, even with a stop more light than you've got at 600mm (bare 600 II at f/4), I find myself needing to use ISO 6400 on the 1D X to get the necessary motion-stopping shutter speed. How do you think the resolving power of the 7D's higher pixel density would hold up compared to the 1D X at ISO 6400?


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## AlanF (Oct 23, 2012)

I was shooting at iso 200. I post photos on a very picky bird website - if it's not tack sharp or free of noise, it will be rejected by the moderators. The noise level at 6400 on a 1D X would be unacceptable for that site. My data are useful for when you have to resolve fine detail at the limits of theoretical resolution. When you are not at those limits and you have more than enough pixels to play with, the FF will outperform the 7D any day because the lower noise and better dynamic range will be more important. But, when those little birds are so far away that they are just a small part of the image, the 7D is better. If you can sneak up on them so they fill the frame, give me a 1D X (please).


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## neuroanatomist (Oct 23, 2012)

AlanF said:


> I post photos on a very picky bird website - if it's not tack sharp or free of noise, it will be rejected by the moderators. The noise level at 6400 on a 1D X would be unacceptable for that site.



Picky, indeed!


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## crasher8 (Oct 23, 2012)

I'd reject that 2nd bird if I was a moderator.


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## neuroanatomist (Oct 23, 2012)

crasher8 said:


> I'd reject that 2nd bird if I was a moderator.



It was in a tree and eating seeds. I get confused easily...


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## AlanF (Oct 23, 2012)

This was rejected for being too noisy.


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## neuroanatomist (Oct 23, 2012)

AlanF said:


> This was rejected for being too noisy.



Is that a 100% crop, or is that the full or slightly cropped image?


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## AlanF (Oct 23, 2012)

Attached is the 100% crop (from a 100-400mm L). And the second one of the kingfisher for not being sharp enough. When I say picky, I mean picky. Your bird pic from the 1D X is far too soft.


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## steven kessel (Oct 23, 2012)

My primary interest is wildlife photography and most of the shooting that I do is hand held because I do a lot of hiking with my camera in rough country. I recently acquired a 7D and the EF-L 100-400 to replace my T3i and a Sigma 150-500 lens. I am astounded by the improvement in sharpness that I'm getting. Photos at any ISO are far crisper with my 7D 100-400 package than with the T3i/Sigma combination taken at the same ISO. 

My point is that I couldn't imagine that there would be that much improvement over what I'm getting with the 7D in a full frame body. There comes a point, and I believe that I've reached it, where my eyes are simply not good enough to tell the difference.


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## neuroanatomist (Oct 23, 2012)

AlanF said:


> Your bird pic from the 1D X is far too soft.



Yeah, it's front-focused a bit, for one thing, and needed a deeper DoF - but it was overcast and near sunset, and I was already at f/4 and ISO 6400...


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## jthomson (Oct 23, 2012)

steven kessel said:


> My primary interest is wildlife photography and most of the shooting that I do is hand held because I do a lot of hiking with my camera in rough country. I recently acquired a 7D and the EF-L 100-400 to replace my T3i and a Sigma 150-500 lens. I am astounded by the improvement in sharpness that I'm getting. Photos at any ISO are far crisper with my 7D 100-400 package than with the T3i/Sigma combination taken at the same ISO.
> 
> My point is that I couldn't imagine that there would be that much improvement over what I'm getting with the 7D in a full frame body. There comes a point, and I believe that I've reached it, where my eyes are simply not good enough to tell the difference.



Since the T3i and the 7D have the same sensor, the effect you are seing is due to the change in lenses.
The 100-400mm is much sharper than the Sigma 150-500 especialy at the long end.
I think that you will see a similar change if you upgrade to FF. particularly at ISO 800 and above, where noise impacts the sharpness of the photo.
Look at Neuro's Cardinal at ISO 6400, this is what I would expect to see from a 7D at around ISO 1600


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## RS2021 (Oct 23, 2012)

neuroanatomist said:


> AlanF said:
> 
> 
> > Your bird pic from the 1D X is far too soft.
> ...



It is good enough to see the little fisher has been tagged with a leg ring


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## paulc (Oct 23, 2012)

On my 5D+85/1.8 the image gets sharper going from f/11 to f/13 while I just won't go over f/8 on my XTi.


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## K-amps (Oct 23, 2012)

AlanF said:


> This was rejected for being too noisy.





Run it through Nik DFine NR 2.0 ... what site is this anyway.


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## crasher8 (Oct 23, 2012)

Really? No one got the noisy bird joke but me? Buncha scientists and engineers not photographers!


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## danski0224 (Oct 24, 2012)

So, if the 7D is capable of extrordinary resolution in perfect circumstances, does this also mean that the rumored high MP count FF camera(s) will also require perfect circumstances? Will cries of "soft" be heard when/if the rumored high MP camera hits store shelves in the near/not so near future?

Maybe the excellent high ISO performance of the 1DX is being "field tested" for the "1DXs"...


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