Originally posted by Tan68 I looked at DX0 'screen' results for K5, K50, A7S
The results did not show the K50 being better than the A7S
The results showed the K50 nearly equal to the K5 with the A7S better than both.
This is what I would expect to see.
I am afraid your arguments are over my head. I am not sure any further comments will help me understand your position. I will have to leave off conversation with you. Thanks for the help, though, and have a good morning.
His arguments are not over your head - they're wrong, and he's also now introducing half-baked info that contradicts how DxOmark themselves even describe the tabs. He doesn't understand the purpose of the 'screen' or 'print' tab**, and has given advice the exact opposite of the truth when he says one should focus on the 'screen' tab when buying a camera. That's a very quick path to buyer's remorse.
'screen' doesn't take into account differences in pixel density or total light (sensor size) - it's not meant to. 'screen' tells you the K3, for example, has worse noise at the pixel level than the K5 - yet anyone who owns both can tell you they're actually pretty close at the same display sizes - which is also exactly what the 'print' tab indicates. Not buying a K3 based on 'screen tab' results would be foolish, no?
There's a reason why DxOmarks aggregate scores and sensor rankings don't track 'screen' tab. For another source, see Bill Claff's PDR site, in which he compares photographic dynamic range, which track DxO pretty closely and show how the crop of a D800, for example, almost exactly matches a native D7000 and K5 shot. As you would expect.
Or, buy a used D800 and compare it yourself
50mm f/1.8 on D800 =~ 35mm f/1.1 on K5 (So if both were at f/1.8 - same exposure - DR, noise would be about 1.3 stops better on D800 in that comparison)
Oops - my DOF isn't deep enough at 50mm f/1.8, uncle Buck's face is blurry! Uncle Buck's face has to be razor sharp! Stop down!
50mm f/2.8 =~ 35mm f/1.8 on K5 (DOF, DR, noise about the same, FF @ f/2.8 vs. aps-c @ f/1.8 there.)
So - as I explained before, you had the
option of stopping down to match K5 output, and you took that option ^
Or, if you don't have that 50mm lens for FF with you and you need to crop:
FF, 35mm f/2.8 cropped to aps-c and displayed at same size =~ 50mm f/2.8 on aps-c native (DR, noise about the same as well.)
Here's a good post on some of this, staying within PF:
Screen vs. Print tab and pixel pitch and cropping
**
for anyone new to DxO - 'screen' tab doesn't mean "how it looks on my screen" and 'print' tab doesn't mean "how it looks when I print." A way to think of the screen tab is "100% crop" and 'print' tab as "displaying at the same size, on screen or print."
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