sigma 70-200 v canon prime

[DavidEB]

I borrowed a friend's EF100 f2 for a couple of days so had a chance to compare it to my sigma 70-200 f2.8. Here are some casual shots of a tree in my backyard, camera on tripod, mirror lockup, and self-timer (to reduce vibration). These were shot RAW, ISO 200, no post-processing, 100% crops. The tree is about 10 meters from the camera. The focus point is on the barcode. Interestingly, exposures were the same for the four pictures (shutter speed doubled from f2.8 to f4). There was no change in the ambient light.

The sigma shots are on the top, the canon on the bottom.

[chuckschilling]

Both seem slightly sharper at f4, the Canon appears to be just a bit brighter than the Sigma, particularly at f2.8. Still, the Sigma seems to hold its own in your tests.

[LightRules]

Both excellent lenses, but it does show that the 70-200EX is a top notch performer. Nice post David.

[PetKal]

That's interesting...while the resolving power of both lenses seems pretty close to me looking at the bar-code alone, I'd say that the overall IQ edge goes to Sigma....the Sigma images are better exposed and the bark shows more texture and less wash-out, compared to Canon shots.

[sinclairbishop]

The Canon shots certainly look sharper to me.

[DavidEB]

Thanks for looking and commenting. The one thing this post definitely proves is that image quality is subjective and not judged the same way by differing people.

To me, the most interesting thing is the difference in exposure. The canon 100mm is a tad brighter than the sigma (check the histograms, it's about 1/3 f-stop) even though the light was the same. Along with Petkal, I liked the sigma images a little more but I think it's because the exposure was more accurate, which is very puzzling.

If I may voice my interpretation (not necessarily more valid than any of yours) the canon 100mm seems a trifle sharper at f2.8 and so close to the same at f4 that I don't care about the difference. In fairness to the sigma 70-200, it's wide open at f2.8 and the canon is stopped down 1. Here's the clip of the canon at f2.0.

fStop -- kind words from the master. thanks.

[rklepper]

The Canon shots certainly look sharper to me.

Yes, I agree. The sigma looks to have some focus issues. Possible AF accuracy?

[DavidEB]

Sorry, doc (and sinclair), but I think they shots are pretty close to equal in sharpness. If anything, at f2.8 in my opinion the sigma is better. The difference is best seen in trying to read the numbers written under the bar code.

One potentially confusing thing here is that the angle of view with the two lenses is different. The sigma is set on the tripod with the lens collar, and the canon is set on the tripod with the camera body, so it is sitting a bit lower. I didn't move the tripod. This changes the view angle particularly for the words "Belle of Georgia" in a way that disadvantages the sigma. But if you look at the focus point (barcode), and look specifically at the numbers, I think you'll see the sigma is a tad better at f2.8. Equal at f4.

and the canon wide open at f2 is dismal. in contrast, the sigma wide open is pretty darn good.