Sigma 28-70mm f/2.8 EX DG Reviews

I consider this a "normal" lens... i.e. a "people picture" lens. You can get a full-length shot at just 10 feet at 28mm, and a nice head and shoulders at the same distance at 70mm. It is a pretty imposing piece of glass, with an 82mm filter. This projects out enough that you can't use the built-in flash wider than 50mm. But I do like the constant f2.8 feature. Fast and sharp.

I recently wrote a user review of the Tamron 28-75 f 2.8 DI, LD I owned about a year ago. In as much as the Tamron, and the newly acquired Sigma EX, DG, are in the same focal, not to mention price range, I'll compare them here.

When the first Sigma arrived I was forced to return it due to a lack of smoothness in the zooming mechanism, and some minor scratches on the rear element. The new one is better, but also has a somewhat larger scratch dead center of one of the internal elements. To start with, I have to say that Sigma may have a quality control issue here, or perhaps just a limit to how much care they'll take in this price range.

I tested the lens with methods of the considerably primitive school of thought, which is, written text taped to a wall. Anyone who's ever attempted this knows well that it's something akin to trying to properly align a phono cartridge so that the stylus sits perfectly in the record groove. I maintain that it's a nearly impossible task, ultimately being an act of faith as to whether you've succeeded or not. None-the-less, the results of the Precambrian method were impressive. This is a sharp lens. At f 2.8 the corners are soft as one might expect, especially if one is using film, as opposed to a smaller digital sensor. Stopped down to f 5.6, or more, I was in the realm of “I can't believe the detail in this negative”. Having done the same kind of test on the Tamron a year ago I recall being in the realm of “I'm not sure if it's sharp, maybe it is, I think?”

The Tamron, is outside of this, mostly less problematic in terms of being able to stack a couple of filters without significant vignetting. Unfortunately, I can't say the same for the Sigma. The problem might be relieved by using slimmed down filters, but I won't know until I try. Overall the Sigma is warmer, and I would say of higher contrast than the Tamron. It depends on what you like, but I prefer the warmth of the Sigma, and am not a fan of cold weather either. The Sigma has subjectively speaking a higher quality feel to it, but both lenses are mostly plastic. The Tamron in theory at least, gives you an extra 5mm of focal length, so that could be a consideration, along with the fact that it's a little more expensive than the Sigma.

I've taken some shots locally with the Sigma, and again, am very pleased with the color, contrast, and detail I see in the prints. So finally, which lens do I prefer? It's the Sigma, due mainly to the fact that for me nothing trumps sharpness, and this lens approaches the sharpness of my old favorite medium range optic, the 35–70 F3.4 Zeiss, which is an unequalled piece of glass in my eyes. Ouch, that sounds painful, let me rephrase.
-Aum