IQ difference of FF vs APS-C?

[jondave]

Hi all, I'm a long-time 7D user contemplating on upgrading to a 5D MkIII. It's known that FF users aren't happy with the 7D's IQ, but how big really is the difference? Is the difference in image quality similar to the IQ difference between a compact (e.g. G12) and an cropped body DSLR (e.g. 7D)? Or am I just expecting too much?

[wickidwombat]

Big difference, I really wanted a 7D based on specs to replace my 1Dmk3 since it was smaller, that was until I saw the IQ personally the FF and APS-H sensors kill the 18mp crops in IQ.

I just decided to keep the 1Dmk3 as a backup and use it occasionally still

It depends what you shoot really and how critical your clients are likely to be
for many the IQ of the APS-C sensors are fine and certainly leave most P&S for dead

of course medium format is better still but crazy expensive

[neuroanatomist]

In bright light, printing 8x10" or smaller, you likely will not notice a difference in IQ (beyond the thinner DoF, which can be compensated for by a faster lens on APS-C, to a point).  If you need to push the ISO up higher than about 400, print large, etc., you'll notice a meaningful difference.  Basically, a FF sensor gathers more total light, which gives you a 1.3-stop advantage on ISO noise and a 1.3-stop thinner DoF for the same framing.  It's significant, but it's not magic. 

[Policar]

The relative increase in sensor size between a compact and APS-C camera is much greater than that between APS-C and full frame.  And everything will look good in good light.  In low light there's a big difference, and there's more microcontrast and shallower depth of field (feels a bit like the difference between medium and large format film).  There's a substantive difference, but a good lens makes a bigger difference.  The 5D III is more forgiving of bad lenses, though; the 50mm f1.8 is great on it, even wide open, since the pixel density is less.

[V8Beast]

It depends who you ask. To my eyes, the difference in IQ is substantial, yet others have trouble distinguishing the difference. IMHO, it's more of a color and contrast thing rather than something that can be measured in a standardized empirical test. That said, spending some time in post processing can bridge the gap considerably, but IMHO the FF files still come out on top.

Nevertheless, if you can't spot the difference in IQ with your own eyes, there's no point in paying a premium for a full-frame body.

[jondave]

So is the IQ difference more on color/contrast/DOF than (low-ISO) noise/sharpness?

[V8Beast]

So is the IQ difference more on color/contrast/DOF than (low-ISO) noise/sharpness?

Depends who you ask In comparing my time with a 7D to my 5D3, the 5D3 has far lower noise. However, it's worth noting that the 7D, IMHO, is pretty darn clean at high ISO considering the difference in sensor size. I don't need to sharpen my FF files nearly as much as I did back when I had crop bodies, either.

Ultimately, it comes down to your budget and your usage. If I were just shooting for fun, there's no way I'd buy an FF body, but there are rich dudes out there that can incur the extra expense

[elflord]

Hi all, I'm a long-time 7D user contemplating on upgrading to a 5D MkIII. It's known that FF users aren't happy with the 7D's IQ, but how big really is the difference?

The sensor is about twice as large, so in theory you get (slightly over) a stop of ISO. That is, all other things being equal, you'd expect the full frame sensor to have comparable performance at  ISO 2000 as APS-C at ISO-800. In practice going from a Rebel XS to 5DII, I found I got about 2 stops.

You also get shallower depth of field for the same fov.

Is the difference in image quality similar to the IQ difference between a compact (e.g. G12) and an cropped body DSLR (e.g. 7D)? Or am I just expecting too much?

No, it won't be comparable to this for two reasons. One is that an APS-C sensor is about 8x larger than a 1/1.7" (e.g. Canon S100) point and shoot sensor. you're only bumping by a factor of 2.56 from APS-C to full frame.

The other is that the point and shoot has a mediocre zoom attached to it. With an APS-C camera, you aren't compelled need to make image quality compromises to cover a large zoom range or keep the lens weight down.

The effect is similar to making all your lenses a stop faster, and you have much more options for fast wide angle lenses.

[Cosk]

I'll answer from a real-life shooting perspective rather than a technical perspective.  My point of view is the answer depends on the types of photos you take.   For me, the big difference I see between FF and crop is the 1.6x stop in DOF. 

For portrait work and creative artistic work, you just can't beat the thinner DOF of FF. 
But I miss my crop body for sports and wildlife photography - where the extra usable DOF and lighter lenses are welcome.

So, I say it depends.  I'm in a portrait/creative phase right now... So for me, FF produces much better images. 

[hyles]

I think that at low ISO difference is marginal, increasing ISO the gap widen. Where I think the biggest difference is, it is more on DR than noise. My 5D has less noise than my 60D but difference is sometimes  scarce, but with my 60D I have to be more carefull not to burn highlight, whereas 5D has greater DR.
Diego

[HarryWintergreen]

As it's already been said, beyond technical ('pixel-peeping') perspectives there's the dof thing that leads you to a more thorough considering of what you are going to shoot. Action and wildlife are crop body's patch. And when sticking to crop bodies good glass is essential (and this opens up a back door to ff  ).

[wickidwombat]

for macro the APS-C has 3 big benefits

1) added reach
2) lens sweet spot
3) the wider DoF of APS-C actually works in the favour of macros where DoF is so crazy thin anyway

[dtaylor]

I have a 17" Epson professional printer and regularly make larger prints. All other factors being equal, with proper post processing 16x20" landscape prints from the 5D2/3 and 7D are indistinguishable in the ISO 100-400 range, and for most shots even 800. In other words if you show a room of photographers the two prints with no labels, they will not be able to pick them apart. If you label them, then some will all of a sudden claim to see 'huge' differences. This is true even if you lie and reverse the labels, demonstrating that the 'huge' differences are due to cognitive bias and not any real differences.

Crop bodies require a bit more sharpening and local contrast enhancement, and sometimes a bit more NR.

At 30" small differences in fine detail start to emerge, but they would escape the notice of the vast majority of viewers.

Above ISO 800 the 5D2/3 just start to pull away. Less noise and higher retention of fine detail. The 7D is good at high ISO, the 5D2/3 are excellent. But even there if you only make smaller prints, you will hardly notice the difference.

[Astro]

well the internet is full of images.

yes full resolution images of APS-C and FF cameras.... so why don´t you decide yourself if the quality is so much better or not?

and this is always a good read to keep things in perspective:

http://www.luminous-landscape.com/reviews/kidding.shtml

[ruuneos]

I'm still very pleased of 7D's quality, but I know that -H and FF beats it like 100-0. Probably looking for FF body in 1-2 years.