Sigma 30mm 1.4 on APS-H, Surprising Result

I just sold my Sigma 30mm 1.4 tonight and the guy who came to buy it, to my surprise, brought his 1DIII to test it out. Now I didn't think this was a huge problem since as far as I know, all crop lenses will mount on full frame or aps-h except the Canon made ef-s lenses due to the way Canon designs the rear of the lens.


I myself mounted this exact lens on a full frame body before and saw a partially circular image, 100% loss in the corners. The guy was buying it for a friend with a 40D so that wasn't really a concern, but what surprised me was that in the quick tests I didn't see much of any vignetting, certainly not total loss even in the far corners. Now the buyer was holding the camera so I may have missed something, but it looked like the full preview to me.





Have any of you tried this or any other 3rd party crop lenses on aps-h with the same sort of results?


It would be interesting info for 1D shooters since the Sigma is a much cheaper and slightly wider option than the 35L and 2/3s of a stop faster than the 28 1.8. I'm sure other 3rd party crop lens offerings would be tempting to aps-h photographers if they knew there was no major light falloff in the corners.


-Yoni