Hi all, I wonder if you can supply some advice regarding a Sigma17-35mm lens I purchased earlier in the year. Basically if I use the automatic or 'P' setting on my Canon EOS 30D camera the image is over exposed by 1 to 2 stops. If I use the same functions with my Canon 18 -55 kit lens the exposure is correct so I would presume the camera is not causing the problem. The only way I can get a correct exposure with the Sigma lens is to compensate manually for each shot. Please note the exposure problem is worse when I shoot outdoors. I look forward to your help Sonia Hunt
Cameras - Sigma
Answers & Comments
Try your EOS in AV (aprature value) mode. You should be able to adjust your aperature value in 1/3 or 1/2 steps dependind how you have your Custom Functions set in your camera's menu. Possibly the lens you purchased is for an EOS 35mm. If you use a 35mm lens on your eos there are some calculations you must use. When using a 35mm lens on the EOS 20D, 30D, 40D and 50D bodies, you must first calculate your focal leingth by 1.6 times. With this, your exposure changes as well.
The only EOS Digital SLR bodies that use a 35mm x 24mm CMOS sensor are the 1D and 5D. My wife uses a Tamron 18-200mm f3.5-5.6 lens on her 20D and loves it.
If this makes no difference, you may have a defective lens.