Sigma 17-50 Yellow color cast.

So in another thread we were talking about the advantages and disadvantages of the 17-5X lenses. One comment made was that the Sigma 17-50 produced a yellow color cast. That user than posted some seemingly strong evidence in this post.

Well I have never noticed this so I figured I would do a test. Here are the test details. I have 4 lenses that can shoot at 50mm: the 18-55IS, 50/1.8, 24-105, and Sigma 17-50OS. I set the camera on a tripod and shot lens in manual mode using tungsten lighting. Settings were ISO 200, f8, and 1/6". I shot in raw and added 2 stops exposure compensation to get the proper exposure in post.

I then took the 18-55 image and used the white balance eye dropper to set the white balance on that image which was 2500 degree with a +3 tint. I applied that same white balance setting to the other three images.  I then took the images and placed them on a powerpoint slide and did a screen shot and uploaded.

This is the result:

So go ahead and tell me which is the Sigma one and see if you can guess the other 3 too.

I will say I am surprised by how different these look. I picked 1/6" to make sure I got enough 60hz cycles in to help average the lighting, so maybe that is causing the differences. I did shoot another set with flash, but I kept the flash in ETTL and it caused too much fluctuation in exposures for an accurate test. I think I am going to go back and test with manual flash to see if that makes this test more consistent between the lenses