EF 35mm 1.4 Overexposing Images

[emmajfurniss]

I shoot on a 5D Mark 4 and my go-to 35mm has been randomly overexposing my images. While shooting in continuous studio lighting and not changing any setting, my images will suddenly start coming out extremely overexposed. I know it is the lens and not the body because none of my other lenses cause this same problem. I've attached images showing my settings that are exactly the same and the photos were taken seconds apart. It will not just overexpose 1 image either, it will affect images continuously after it starts malfunctioning. 

[Waddizzle]

You seem to have a lighting issue.  

Are you using LED lighting?  Have you enabled “Anti-Flicker” compensation”?  What specific lenses are you using?

What Metering Mode are you using?  What AF point(s) and AF mode are you using?  AF point selection has a direct impact on metering,

I would use One Shot AF, Evaluative Metering, and the center AF point for this type of shot.  Spot AF and Spot Metering do not work the way many people seem to expect.  I would not use ISO Auto, either.  I would use M mode with ISO set to 100.

Spot AF does not necessarily permit more accurate focusing.  Spot Metering does not necessarily permit more accurate metering.  When combining these two settings, one should only use the center AF point.  These options will only work as one might expect with the center AF point.

[jrhoffman75]

Perhaps the aperture blades are sticking? If that happens again actuate the depth of field button while looking into the lens and see if the blades are closing down.

[rs-eos]

Yes, it does sound like the lens isn't stopping down.   If that's the case, a short-term workaround is to always use the widest aperture until you get either a replacement lens or send in your current one for repair.

[MikeSowsun]

I am quite sure your problems is related to your “continuous studio lighting”. You probably don’t notice it with your other lenses because they are slower lenses requiring slower shutter speeds. Fast shutter speeds will not capture the entire light cycle and produce exactly what you are seeing. Switch to video mode at f/2 and 1/500 and you will see the same effect. 

Just slow your shutter speed down to 1/60 or. 1/125 and your problem should go away.  

As “Waddizzle” says,  enabling “Anti-Flicker”  should also help.

[Waddizzle]

Of course, I agree with Mike.  The issue is almost certainly related to the lighting.  Without knowing more about the lenses involved, I have no explanation for why the issue seems limited to certain lenses but not others.  

Could it be that two of your lenses have sticky apertures while your other two lenses do not?  Sure, anything is possible.  But that scenario seems to be an extraordinary stroke of bad luck.

[EDIT] I am not inclined to suspect a lens malfunction.  Failing aperture blades tend to fail and stay that way.  “They’re dead, Jim.”  

Mechanisms do not intermittently work and then sometimes they don’t.  They don’t die on you and then come back to life for a few shots and then die on you again, much less repeat the same process over and over.

[ebiggs1]

"The issue is almost certainly related to the lighting.  "

Another vote for lighting being the cause. Plus the white BG can be a problem and variable. I would first reset the camera to default settings. Try each metering mode to see which works best. You do not need to go full M mode but Av or Tv may work better. I would set a fixed ISO and WB.

I am about to start this journey next week with Senior photos and I will be using a white BG. I typically find Av to work best with Evaluative Metering but the senior takes up most of the frame unlike yours where the frame is mostly white.