APS-C IMAGE QUALITY VS fULL fRAME AT TESTING

Started Feb 24, 2013 | Discussions thread
qianp2k Forum Pro • Posts: 10,350
Re: APS-C IMAGE QUALITY VS fULL fRAME AT TESTING

schmegg wrote:

qianp2k wrote:

schmegg wrote:

Fine. I choose the 100/2.8 L macro and I choose to shot at maximum macro magnification - because I wish to resolve as much subject detail as possible!

Check out DXOMark, 100L/2.8 IS macro resolves more even on 12.8mp 5D over 18mp 60D/7D when frame the subject into the same FOV that is the key, not from the same distance then crop out 5D photo to match 7D's FOV. Otherwise they are different photos with different FOV.

What will I find?

As DXOMarks test, FF even a 12.8mp 5Dc still outresolves 18mp 7D.

So it is your contention that DxO claim that a 12.8MP 5D outresolves an 18MP crop.

You are wrong - the DxO data does not tell us that at all.

Yes it does black and white there.  Even with the old MTF measurement, DXOMark shows the same lens 24-105L resolves more on 5Dc than on 7D (53lp/mm vs 47lp/mm) or comparable EF-S lens 17-55/2.8 IS.  They measure when frame the subject into the same FOV.

The DxO data simply tells us that if we deliver more detail to the sensor of the 5D than we do to the 18MP crop, the 5D will deliver sharper images. One could extend this to assume that it also means that it outresolves the crop, though this is a bit of a leap.

I don't understand what you mean deliver more details?  DXOMark tests the sensor-lens combo and shows all EF lenses are resolve more on 5Dc than on 7D.

You cannot separate sharpness from fine details (resolution). That's why now DXOMark changes to more meaningful perceptual sharpness as defined here - the actual perceived resolution human eyes can see which is the same meaning of fine details I used.

DXOMark says that in many circumstance upto 45% of megapixels are lost due to lens or sensor defects. You can squeeze in tons of pixels as in 41mp Nokia 808 cellphone camera but the issue is that the lens simply unable to resolve fully that 41mp. Its pixels are so mushy that cannot effectively resolving fine details. What actually can be perceptually resolved is only matter not theoretical amount of pixels.



Equally, we could deliver more detail to the crop sensor than we do to the 5D's, and in that case the crop will almost certainly outresolve the FF 5D.

Not in the case if you frame into the same FOV, the way DXOMark used in its tests.

This shouldn't come as a surprise to anyone - when comparing sensors for resolving abilities by delivering more detail to one than the other (a flawed approach), the one who has been given the most detail to record usually resolve more! LOL!

You are just trying to avoid facing crop magnification. You really need to understand that with 7D has 1.6x times more enlargement which is the same as 1.6x digital zooming that effectively losing the quality of pixels (clarity and sharpness) when project into the same output on screen or on print.

Of course, this tells us nothing about which camera actually resolves more detail - just that the one who has more to record will usually do so.

DXOMark clearly shows 5Dc actually resolves more fine details (or perceived resolution) than 7D when frame the subject into the same FOV with the same lens.

However, if you deliver exactly the same amount of detail to both, then the crop will outresolve the full frame 5D. That's because, when the test is constructed to test which camera actually resolves more detail, the crop wins.

Still I don't understand what you mean "deliver amount of details" that is the same as amount of pixels? Again read carefully the DXOMark explanation below. It shows the theoretical amount of pixels have to pass the reality of sensor and lens combo before can actually resolving the fine details (perceived resolution) human eyes can actually see.  As I said 41mp Nokia 808 simply cannot resolve the fine details that a 12.8mp 5Dc can deliver as seen by our eyes.

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



Really though, that shouldn't come as a surprise to anyone either. And it beats me why some people argue so hard about this simple fact!

It's no surprise at all. I only see a few who actually never own and experience much of 5Dc are arguing here. Most who experience both (like me) understand FF actually resolves more fine details than crop if you frame them into the same FOF.

As I said numerous times in the past, I never claim a crop cannot outresolves more than a FF. It would require a much better lens and lots more pixels to overcome the penalty from crop magnification. I will not be surprise 24mp APS-C with a top lens resolve more than 12.8mp 5Dc even frame into the the same FOV. But I have to wait to see DXOMark confirms that.

DXOMarks just confirms "The Perceptual MPix measure confirms certain rules of thumb such as “a 12 MPix full-format camera is sharper than an 18 MPix APS-C" as said in the above DXOMark link. DXOMark's MPix is not just sharpness as you understand, it's perceptual sharpness which combine MTF into perceived resolution - it indicates the ability of the lens and other optical components of a camera to utilize, from a visual perspective, the number of pixels of the camera sensor.



5Dc photos are not only just sharper but actually resolves more fine details.  I have no doubt that if I used 60D with the same lens (24-105L in first and 50/1.4 in second) and frame into the same FOV, it will be less sharpness and resolves less (clarity or fine details that actually can be resolved and can be seen by your eyes).





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