Overexposure with Nikon D7000 and Sigma 28-135

HI,

I've got a Sigma 28-135mm f/3.8-5.6 Aspherical IF Macro and it causes overexposure by about 2 stops with my Nikon D7000. I've compared exposure with the lens on my Nikon D90 and also with a Nikkor 18-55 G on both bodies. Does anyone know why/how the lens might be leading to exposure and if I can do anything to fix it?

 

Thanks

Donal Murphy

Just to be sure:

• On the D7000 with this Sigma, does the metering already indicate a 2-stop overexposure, compared to the D90 with the same lens? Or is the 2-stop overexposure only visible in the image once you made an exposure?
  
• Is it correct to assume the 18-55 has near identical exposure on the D90 and D7000, and that the D90 with the Sigma lens has comparable exposure to the D90 with the 18-55?
  
• Assuming the Sigma lens has a dedicated aperture ring (unlike the 18-55G), do you have this ring set to the smallest aperture (f/22 or f/32 probably) ?
  

 

The reason to ask for the first point is that metering is done with a lens wide-open, and the aperture is only closed down when making the exposure. If the metering is already off, it means the D7000 does not seem to communicate correctly with the lens. If it only happens on exposure, it could be related to the linkage that closes the aperture during exposure instead.

Have you checked the aperture blades on the lens making sure they open and close properly. Also check for oil on the aperture blades. That can and will cause exposure problems.