wholly unscientific comparison 17-55 IS vs. 17-85 IS on 350d

Started Jul 16, 2009 | Discussions thread
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Juardis Contributing Member • Posts: 721
wholly unscientific comparison 17-55 IS vs. 17-85 IS on 350d

I took my own advice. I rented a 17-55 IS and compared it to my 17-85 IS on my Rebel XT. Everyone says how great the 17-55 is and I wanted to find out for myself if it is that much better than my 17-85 since everyone also says the 17-85 is crap (well, ok, almost everyone that is).

So here are my unscientific conclusions.

1. Color is better on the 17-55. I took a RAW photo of the xrite colorchecker color rendition chart with both lenses and printed them out on 8X10 canon photo printer pro II paper on my Pixma MP980. Regardless of whether my printer is calibrated or not (it's not), the differences should tell me which lens reproduces the more accurate color. Comparing to the chart, the 17-55 wins by a slight edge (in all colors, no bias that I could see). For those of you that don't know, the xrite colorchecker is an 8.5x11 swath of 24 different color squares. The 17-55 did a slightly better job of reproducing all 24 of those colors.

2. Lens aberration is better on the 17-55. Noticeably better. At 17 mm, my 17-85 is terrible with distortion. It resembles a bird in flight if you can imagine the silhouette of a bird in flight (raised at the edges, sunk in the middle). The 17-55, at 17mm, exhibits a more gradual, much less noticeable, u shape to it. I took a picture of my brick wall to figure this out and no contest, 17-55 wins.

3. CA. No contest. 17-55 much better. 17-85 exhibits purple fringing, very noticeable at 200% zoom in DPP, 17-55 not noticeable at 200% zoom in DPP. 17-55 wins.

4. Sharpness. Really disappointing. I took shots at 17 mm, f4.0 (manual exposure on a tripod centered on the same point so everything was the same) and the sharpness was, for all intents and purposes, the same. That is, fuzzy, when zoomed in 200% in DPP. Fuzzy at center, fuzzy at corners, fuzzy all around.

My number one complaint with my 17-85 is that the shots are not, repeat, NOT, sharp at wide angle. Since I get the same results with the 17-55 as I do with my 17-85, and since everyone swears that the 17-55 is much better in this regard, I can only conclude my body, the Rebel XT, is flawed. Or rather, the AF capability of my XT is flawed. Or rather, my 350d is not good.

5. Conclusion. 17-55 is the better lens (duh), but not so much for me to justify an extra $1000 ($650 if I can sell my 17-85 for $350). I didn't go into the extra capabilities of the 17-55 (like f2.8), or the shortcomings (lack of 55-85mm), but I would say that I missed the the extra reach but appreciated the faster lens. So I'll call that a wash, slight edge to the faster lens since I can always crop to make up for the lack of reach.

Oh, one more thing. The 17-55 is a 77mm dia lens, and it's long. I have a 10-22, so I know what a 77mm dia lens will do, but since the 17-55 is longer in dimension, it interferes with my pop-up flash. If I have the lens hood on, the shadow cast by the lens/hood combo could (probably will) ruin a picture. If I take the lens hood off, there is still a crescent shaped shadow at the edge of the picture that may, or may not, ruin the picture for you. I don't know if the 400d, or any other variant of Canon bodies, fixes this, but with the 350d, this could be a problem.

As with the 70-200 2.8 IS that I rented a few years ago, the conclusion I come up with is that it's potentially a more useful expenditure for me to upgrade my body than it is to upgrade lenses. Yes, the better lenses will give me better results, but not so much that I'll be happy with them. I guess the only other thing to rent is a body to see if my conclusion is valid. I suspect if I upgrade both lens and body, the results will be much improved and I'd be a much happier camper. YMMV.

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