APS-C IMAGE QUALITY VS fULL fRAME AT TESTING

Started Feb 24, 2013 | Discussions thread
MOD schmegg Veteran Member • Posts: 5,768
Re: APS-C IMAGE QUALITY VS fULL fRAME AT TESTING

MAC wrote:

schmegg wrote:

MAC wrote:

schmegg wrote:

Redteg94 wrote:

You're not enlarging the FF image as much, so it isn't as "hard" on the lens in question. This allows an FF sensor to provide more resolution than APS-C even if it has less MP (as long as you frame the same/are not FL limited). For example, I've noticed that the 13MP 5D will give slightly better resolution than the 18MP sensor in my 7D if framed the same.

Sort of - though I fear you may be making the same error that a few others do here.

The 12.8MP 5D definitely does not resolve more than the 18MP 7D. The whole idea is ridiculous as the sensor has about 5 million pixels less resolution.

not according to dxo and gianp2k!

did we ever hear from Andy W.?

Though I think you could be correct, we need a "proper test"

To take a 50 and physically move closer to get the same framing - duh - moving closer my eyes see more resolution, more fine print, when I move closer.

The farther way to go to magnify from a small sensor vs the lesser way to go to magnify from a big sensor also has some impact.

the lens behaves differently on different cameras

the aa is different

lots of differences

I wouldn't use "definitely"

We need to see a proper test!

Just curious about ...

1. What was wrong with the test I posted earlier in that other thread? Do you consider it to be not "a proper test"?

needs same distance, same fov. So can't use same prime lens

2. If you think something was wrong, how would you design a test for comparing the resolving abilities of two different sensors?

70-200 II, same fov, resolution chart looking for line pairs

then, after seeing which is better, describe what it means in how large one would need to go to see the difference in a gallery when viewed from 5 feet:-D

Big problem here is that you are presenting different amounts of detail to the sensor plane. Doing so pretty much kills the ability to draw any useful conclusions. (I'm sure you know this MAC).

The only way the determine which sensor is capable of resolving more detail is to present exactly the same image detail to both and then compare them at 200% or 300%. Any other approach is flawed when trying to determine resolving power.

The reason you don't see test sites do this is simple - it's obvious that the higher resolution sensor will resolve more. No need to test this - but it's a pity they don't because we have armchair experts running off to DxO et al using lens test data to falsely determine sensor resolving abilities.

But sharpness (which is NOT resolution) is a factor of more than resolution. The other big contributor is acutance. And it is this parameter that the 5D is ahead in, because the big pixels, which resolve less, provide better acutance. So overall, the sharpness may appear better even though the sensor is resolving less detail. This difference can largely be eliminated with use of proper sharpening though, leaving more detail resolved and very similar sharpness in the 7D image.

sharpening ain't a good thing - > more noise

better acutance is noticeable. others discount my claim of weak aa. probably weak aa AND those nice Big Pixels

Yeah - I didn't mean to be dismissive. The AA filter would have some effect (if, indeed, it does have a weak AA filter).

it does:-D

Obviously the AA filter will play some part. And, though I haven't bothered, it'd be easy to find out how much by doing some poking around on the net to find some decent tests between the D800 and D800e.

Of course, weak or non-existent AA filters introduce their own issues, so it's not all champagne and caviar.

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