35mm f2 IS underexposing?

This is weird, but my 35 f/2 IS seems to consistently underexpose by about 1/2-1 stop.

I don't think this is a camera body issue, and my other lenses work fine on my 6D. Not a huge problem since I can compensate by overexposing a bit, but has anyone else maybe noticed this about this lens?

Does it do it at all F stops?
What are you using for metering?

I wonder. Can the lens report a faster aperture to the camera than it is actually using? If it is telling the camera it is at f5.6 but the blades are closed enought to be f8 it would do this. Just guessing.

Personally I would go to a local camera shop (Like Sammy's here in socal) and try one of their demo copies.

My Canon 50f1.4 overexposes by 1/3 stop. This can be a problem outside, but hasn't been for low light shooting
My 35F2IS has been right on for both my cameras.

Can you post a sample with EXIF intact?

The 35IS has significant vignetting. Its actual transmission is not f/2. This why, relative to, say, f/2.8, a shot at f/2 will be underexposed. Ditto for the many other fast lenses.

^^ Agree with the vignetting, but according to the link below, the T-stop value is 2 for this lens vs. f2.3 for the old non-IS version. So that wouldn't explain the underexposure.

http://dustinabbott.ne​t …ef-35mm-f2-is-usm-review/

Abu Mahendra wrote in post #17218918
The 35IS has significant vignetting. Its actual transmission is not f/2. This why, relative to, say, f/2.8, a shot at f/2 will be underexposed. Ditto for the many other fast lenses.

Yep, this was it. The vignetting was so heavy I thought the entire picture was underexposed. Whoops. That and poor lighting conditions made it worse. Easy LR fix.

jrscls wrote in post #17218957
^^ Agree with the vignetting, but according to the link below, the T-stop value is 2 for this lens vs. f2.3 for the old non-IS version. So that wouldn't explain the underexposure.

http://dustinabbott.ne​t …ef-35mm-f2-is-usm-review/

I'd first look to the vignetting map of DXO, SLR Gear, Lenstip, Photozone and DP Review first. They all show the 35IS to have significany vignetting at f/2.

I always dial in +1/3 stop exposure comp (and HTP to take care of any over-exposure at other apertures) so I don't notice it on most shots. Dial in, and forget. I also shoot RAW only, so you can fix, if needed, in DPP.

My 35 IS doesn't do that. Have you tried loading the lens profile?