Photography - Sigma 17-50mmOS

Overview

The use of the short primes (35mm f/1.8 and 50mm f/1.8) really opened me up to available light photography, but I'm constantly switching back-and-forth, or trying to zoom with my feet. I decided that it was time to pick up a fast zoom. I tried a couple of options, and was very pleasantly surprised by the Sigma 17-50mm OS.

My Nikon D90

Sharpness

This lens is sharp. The center of all images is quite sharp throughout the zoom range, even wide open. The borders are reasonable good at f/2.8, but are noticeably less sharp than the center, when under 30mm. Stopping down to f/4, the image is virtually even, across the frame. 50mm@f2.8 sharpness is comparable or better than the 50f/1.8, at the same aperture.

Focusing and Other Notable Attributes

The Sigma is as fast focusing as any lens I've used, and other than a couple of misses at 17mm-1/15"-f/2.8-ISO800+ focus was bang on. Honestly, this could just as easily have been as a result of user errors... I also tested the Tamron 17-50VC and, overall, I'd say speed was equal, but the Sigma was far less prone to mis-focusing.

There is some minor distortion, at 17mm, but it is pretty minimal, from my preliminary tests. No where near as noticeable as the Nikon 18-105VR. Otherwise, the optics of this lens are near superb. There are some reports of field curvature, which I haven't noticed, yet. I will continue to test and will update this page, as required.

Handling and Use

Weight is nicely balanced on the D90; the Sigma 17-50OS is about the same size as the Nikon 18-105VR, but is noticeable heavier. I wouldn't have any problems carrying the body + lens around my neck, all day long. The 17-50 range translates to 25-75 on a DX body; this is the classic "event" range, and I can see why. Strictly shooting indoors, there would be almost no need for a second lens; the range is great.

The OS (optical stabilization - same as Nikon's vibration reduction) works well on this lens. I haven't put it through the rigors of heavy testing yet (only be a few days), but even with my shaky hands, I can easily handhold 1/15" shots of static subjects. No way could I do that without the aid of stabilization.

I wish the Sigma had some form of weather seal, or a rubber gasket, rather than the bare metal visible when mounted; I gather this is due to the larger Canon mount this lens also accommodates. This is my first non-Nikon lens, so the zoom ring spins the wrong way, for me, and the focus ring spins while AF'ing, so I need to get used to these quirks, but these (relatively) minor nits weren't enough to scare me away from an otherwise very good lens.

Sample Photos

Here are a few samples I have taken with this lens:

DSC_3156

DSC_3021

DSC_3090