My Nikkor 10-24 arrived today, and we will have to see how it stacks up against my trusty Sigma 10-20. For kicks, here's a line-up, with the Nikkor vr16-85 standing in to convey a rough idea of sizing (he'll also see some action later on in this page). As I anticipated, the Nikkor 10-24 is roughly the same length as the vr16-85, just a tad longer. Interestingly, it's shortest length is at around 15mm, so that's how I store it. The Sigma 10-20 is the shorter of the three. Both the Sigma 10-20 and the Nikkor 10-24 have a 77mm filter thread diameter. That means I won't need to invest in a new Circular Polarizer, among other things.

I hope you find the following side-by-side samples useful as you perform your own comparisons and assessments. My bottom line: these are both great lenses for achieving super-wide compositions, and since I end up using this lens at 10mm more often than not, I limited my shots to that focal length.

All samples were taken with a Nikon D90 and mounted on a tripod, at fixed exposure settings, varied in 1 stop increments, and with pre-set White Balance.

Initial impressions:

• In general the Sigma 10-20 seems to let more light in, which might come in handy in low-light photography -- or alternatively, may lead to over-exposure in bright sunny conditions, though I've never had an issue with my copy. All these were taken in Manual mode with the same exposure for both lenses (i.e., metering did not cause sample to sample variation), and yet most of the Sigma shots, especially outdoors, have +0.1-0.3EV more exposure than the corresponding Nikkor 10-24 sample taken at the same exposure settings.


• On the other hand, the Nikkor seems to be more consistent from one equivalent exposure value to the next, whereas the Sigma seems to vary in the amount of light it takes in from one equivalent exposure to the next. This seems to be more pronounced when stopping down from a wide aperture (see the first Sigma sample at f/4 for sets #4 and #5, for example).


• The Nikkor seems to best the Sigma in the corners and along the frame edges, where the Nikkor has cleaner lines, probably due to less Chromatic Aberration... though I'll leave that to the experts. This is even visible at f/5.6, and even at f/8: see the 1st and 2nd samples in set 1, up top along the roof's eaves on the right-top corner, and in the white fence toward the bottom left.


• Though it may be early to tell, the Nikkor seems a surer focusing machine. The Sigma missed a couple of shots, one of which I went ahead and posted here: 1st sample in set #2. Focus point was dead center on the foreground flower, and the Sigma front-focused with focus on the background foliage.


• The zoom ring on the Sigma has always been a bit of an annoyance for me. It very easily spins, as it doesn't want to stay at 10mm. The Nikkor's zoom ring seems to have more friction and doesn't not easily spin out of place.

While I was out and about, I went ahead and ran a few samples of the Nikkor 10-24 against the VR16-85 in the overlapping focal range of 16-24mm. Here are a few of the results.