Tamron AF 24-70mm f/2.8 SP Di USD VC vs. Canon EF-S 17-55 f/2.8

[bmpress]

I read your review of this new Tamron, and would like to ask you to compare it on your 5d full frame camera against using the Canon 17-55 f/2.8 on your 7d camera.

Since using the Canon lens on my own 7d and loving it very much, I am trying to get a sense of satisfaction level by moving up to the new Canon full frame camera and this Tamron lens.

Thanks, Bob. Your reviews are excellent.

[Bob Atkins]

I didn't get a chance to do a direct comparison, so it's a bit hard to say. The other factor is that I was using a 13MP 5D for full frame and an 18MP 7D for APS-C, so the 7D images would have significantly higher sensor resolution and this affects looking at 100% crops.

At the wide end the EF-S17-55 shows a little lower distortion, a little less vignetting and a little better corner sharpness than the Tamron 24-70/2.8, but things even out more at the longer focal length settings.

My gut feeling is that if you had a 5D MkII (or III) then the advantages of full frame and the Tamron lens would result in higher overall image quality then the crop sensor with the Canon EF-S lens with the lenses set to give the same field of view, plus if you are going for shallow depth of field you'll see a bigger effect on the full frame image than on the APS-C image.

An immediately obvious difference? No, not really unless you're looking at 100% crops on a monitor or large prints. Worth the cost of a 5D MkII/III and the Tamron lens? Possibly, depending on if you have a spare $4000 you're looking to spend and will be using the  full frame camera to dull advantage with a set of high quality full frame lenses. Not worth $4000 just for the switch from 7D+17-55 to 5D2/3+24-70 though.

[bmpress]

Thanks for your rationale, Bob. Every time I try to justify moving up to full frame, the analysis says it is plum not worth the money. I can only justify the switch if I ever get into landscape photography in a big way. And adding to this sentiment, I am totally satisfied with the 7d. It is the finest camera I ever had, and lacks nothing to make my pictures better.

[Bob Atkins]

Yes, the 7D is pretty good. However I can tell you that the D800 gives cleaner and lower noise images. You can underexpose the D800 by 6 stops or more and you can dig down into the deep shadows and bring back a halfway decent image. It's noisy but the noise is clean and uniform. Try the same thing with the 7D and you get a noisier image but with significant horizontal banding. The D800 shot looks much better!

However if you're not digging way down into the shadows and noise, the 7D is just fine, in fact it's very good.

Don't know what the 5D MkIII looks like under the same conditions because the promised loaner has not arrived yet. Hopefully I'l get a chance to look at one and report back before too long.