Do the Canon 5D and 5D Mark II differ in exposure compensation at very wide apertures with the same lens?
Asked 10/25/2013
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When shooting with the same fast lens wide open (for example f/1.2 or f/1.4), some cameras appear to apply hidden ISO/exposure compensation when they know the lens aperture electronically. If lens contacts are broken or a manual lens is used, that compensation may not happen.
Has anyone compared original Canon 5D and 5D Mark II behavior using the same lens, same shutter speed, same ISO, and same scene, both with normal lens communication and with lens contacts disconnected? I'm trying to confirm whether these bodies differ in how much exposure changes at very wide apertures.
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
12y ago
2 Answers
5
I only have odd numbered 5Ds, but the pixel pitch is very similar between the 5DmkII and 5D mkIII so the results ought to hold up.
Here's the same scene shot using a tripod under the same lighting, 1/8s exposure ISO 100, f/1.2 (using the Canon 85L). RAW, converted with ACR with the same settings (everything on zero with a linear tonecurve).
I shot pairs of images with each camera, the first with the lens mounted normally and the second with the lens twisted slightly to break contact and hide the aperture info from the camera body:
5D
5D mkIII
The luminance values for the lightest grey patch with and without aperture information were 76 : 73 for the 5D and 75 : 70 for the 5D mkIII
As expected the difference in exposure is greatest with the 5DmkIII due to it's smaller pixels (the markIII loses more light with ultra-fast lenses).
However the difference between the actual and camera-adjusted images seems less than the 0.4EV and 0.65EV suggested by the DXO chart. So either the loses aren't as bad as DXO states or the camera is not adjusting the images by as much as it should do. Unfortunately I don't have the necessary equipment to say for sure.
Originally by user1375. Source · Licensed CC BY-SA 4.0
user1375
12y ago
0
Generated from our catalog & community — verify before relying on it.
Yes—based on the shared test results, Canon bodies can produce slightly different brightness at very wide apertures depending on whether the camera knows the lens aperture, and newer bodies seem to show a slightly larger correction.
In the example test, the same scene was shot RAW at ISO 100, 1/8 s, f/1.2, once with normal lens communication and once with the contacts broken. On the original 5D, the measured patch brightness changed only a little (76 vs 73). On the newer body tested (5D Mark III, used as a close proxy for the Mark II), the change was a bit larger (75 vs 70).
So the effect is real, but modest—only a small fraction of a stop, not a dramatic difference. The main takeaway is that exposure at very wide apertures can vary slightly depending on whether the body can identify the aperture electronically, and different camera generations may handle that compensation differently.
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