Absurd Singularity

As for the photos, what I did with each lens was take 3 shots at each of the following lengths (24mm, 35mm, 70mm) and apertures (2.8, 4, 5.6 and 8). ISO was set to 200, no flash was used, IS was turned off on qualifying lenses, center focal point, existing light source from window to the left letting in some feeble mid-afternoon light, RAW mode, shutter tripped by timer. Out of the 3 at each range/aperture level, I'd pick what I considered the best and took 100% crops out of the center region. The focus was centered on the purple "P" with the white with grey stripes background. Note also that the 2 books to the right of the book with the purple "P" were set about an inch forward while the 2 books to the left of the purple "P" were set about an inch behind. Between each shot I would manually focus the lens out to infinity and then focus again twice before taking the shot. Except for the Sigma. Because it's not USM/HSM, I couldn't change the focus manually while it was in AF mode. I would have had to switch it over to manual mode every time (flip the switch and toggle the focus ring) which would have been a huge pain in the ass so I did without. Photos were converted to JPEG with Photoshop CS2 with no sharpening and at JPEG maximum quality (10). But enough babble, on to the peeping.

First up, 24mm at f/2.8. The Canon 17-55 is actually at 23mm.

Interestingly, between the two 24-70s, the Sigma actually looks pretty good here. Sharper and with more accurate color rendition on the purple lettering compared to the Canon. Somewhat peculiar is the softness on the right of the Sigma image starting from the "Eyes on the Prize..." book. This crop was taken pretty much from the middle of the actual photo so it's not like we're talking about center/edge sharpness differences. The best looking shot seems to be from the 17-55. Granted 24mm for the 17-55 is not the start of its range as it is for the other 2 lenses but still, it looks pretty good across the board.

24mm @ f/4.

At f/4, the Sigma 24-70 and Canon 17-55 is practically neck and neck with the slightest of edge going to the Canon because of the fuzziness on the right side with the Sigma. The Canon 24-105 shows it face here and does a very respectable job being wide open. The Canon 24-70 is surprisingly still lagging at this point.

24mm @ f/5.6.

At f/5.6 the Canon 24-105 and 17-55 are pretty much in a dead heat. The Canon 24-70 is starting to show some signs of life and the Sigma 24-70 lags a little. Must have been a bad shot. But it's starting to look like this copy of the Canon 24-70 may not be the sharpest at 24mm.

24mm @ f/8.

And at f/8 it's pretty much all equal except the Canon 24-70 is still just a touch softer.

Moving on, 35mm @ f/2.8.

Wide open at 35mm, the 17-55 is razor sharp and looks fantastic. The Canon 24-70 kicked it up a notch and looks pretty good here. The Sigma 24-70 took a bit of a dive here. Not sure if it was a misfocus or a frontfocus problem but the 2 books to the right of the center one looks ok while everything else doesn't.

35mm @ f/4.

At f/4, the Canon 17-55 is still kicking ass. The Sigma 24-70 is mounting a comeback as it looks very good except for the book on the far right. The Canon 24-105 shows up again and does a decent but uninspiring job. The Canon 24-70 apparently went out to lunch although the right side of the crop does look better than the Sigma.

35mm @ f/8.

The Canon 17-55 is proving to be quite the consistent performer. The Canon 24-70 actually comes in second this time edging out the Sigma because of the Sigma's sharpness problem on the right side. The Canon 24-105 comes in last lagging just a tiny bit behind.

And now 70mm @ f/2.8.

Here the Canon 17-55 is actually at 55mm and not 70mm but I figure since all 3 lenses are at their maximum length it should still make a good comparison. Between the 24-70s, the Canon shows significantly better sharpness with the Sigma having an odd dreamy look to it.

70mm @ f/4.

At f/4 all three Canons are looking very good while the Sigma is still looking rather milky.

70mm @ f/8.

At f/8, all 4 lens get a clean bill of health. Looks great all around.

So what conclusion can we draw from these few comparison shots? The looked down on EF-S ("not an L lens") Canon 17-55mm f/2.8 IS is quite an impressive lens when it comes to image sharpness. I don't think there was a shot anywhere at any length or aperture where it was soft. In normal use, while I wasn't expecting IS to really make a big difference at this range, it still made taking steady shots easier. It does suffer from some vignetting issues occasionally but that's easily fixed during post-processing. And while some reports say that it has distortion issues at 17mm, I personally don't notice those kinds of things very much so it doesn't matter to me. For me, this lens is a definite keeper. Since I normally carry at least 2 lenses on photo excursions, the gap between 55mm and 70 is pretty negligible to me.

The Canon 24-105mm f/4 IS is also looking to be a very good all around lens and consistent performer. True it doesn't have f/2.8 but if you spend most of your picture taking outdoors, it shouldn't be too much of an issue. However, it does have a bit of a contentious bokeh though. A lot of people hate it. While I'm mostly ambivalent about it, I can see what people are complaining about. On the other hand, many 5D owners swear by this lens. While I currently own this lens, I may give it up until the day I finally go full-frame, whenever that may be.

The Canon 24-70mm L USM turned out to be a disappointment. At least this copy was. It gave a sneak peek at what a good copy may be capable of only in the 70mm shots. And while it obviously is much better built than the 17-55IS, it loses out in terms of size, weight, sharpness and IS. For a 1.6x crop camera, I think the 17-55IS is quite possibly ideal for a slightly wide to mid-range zoom. Although the 24-70 does have great bokeh and does a great job of making the subject pop out of a background.

The Sigma 24-70 EX DG Macro worked out about as well as I thought it would. For the bargain basement price that I had picked up this copy for, I've got no complaints. Sigma does have a not so good reputation of having poorer than normal quality control when it comes to their lenses. But if you're on a budget, can live with the absence of HSM/USM, can stand the rather loud noise the motor makes while focusing, and can find a sharp, used copy, then it's definitely worth the money.