This is an unusual battle in that I am pitting the Tamron mid-range (a.k.a. “wedding”) zoom for FX against the Sigma mid-range zoom for DX. I am doing this because I have been using the Tamron since getting my D600 (camera and lens both bought separately at different Timmy's via Kijiji LOL) and I would like the flexibility of using the D7200 for that range instead. The Sigma gets magnificent reviews and I saw that Amazon in Canada has them for a very reasonable price, so I took a shot.
My initial impression was very positive, with the Sigma looking like a serious lens, with the lens hood almost comically wide when reversed onto the lens. The Sigma feels great in hand, with enough heft to again feel like a serious lens. Of course, the Canonesque reversed zoom direction is disconcerting, but other than that I really liked it right off the bat. I took a few shots with it and they seemed nice, but I thought I had better test it against my Tamron, which has minor issues down the extreme left side and the extreme top right corner. but not enough to put me off that lens. This was purely about flexibility.
Note: For some reason, the images I upload in Open Live Writer do not have links to open the original size, but if you right click and open in new tab, you will see the original sizes. Those show the issues much better than the smaller sizes you see inline with the text.
I ended up having to run the test at 70mm on a test chart 5 times. In the middle two, I played with various AF fine tune settings, but in the end I could not get sharpness across the frame for the Sigma. The center was mushy, with discoloration that pretty much has to be wicked CA or something similar. See below …
The outer reaches are a mixture, with one lens slightly better than the other in various spots. But the Tamron is better more often and is much better down the extreme right edge. Even F5.6 does not clean up the Sigma there, which is tragic. See below …
None of this matters, of course, after seeing the mushy center.
Of course, the reviews do talk about Sigma’s legendary sample variation, at least in the consumer range, so I should not be surprised to get some kind of decentering thing going on. But it is disappointing as I have no patience to go back and forth with Amazon, and I don’t want to pay the higher prices at the shops right now. So back it goes and I will continue to use my rather excellent copy of the Tamron 28-75 as my short to mid-range zoom.
Too bad … because I love the idea of having both HSM and OS available for travel in low light situations (e.g. churches) …
