Quote Originally Posted by tkerr
My only concern would be, what kind of field curvature do you get from the f/2.8 17-55 ?

What do you mean by field curvature?


Do you mean the formal definition,when a lens projects a curved image on the film/sensor plane, instead of a flat image? If so,both lenses exhibit very low field curvature (the 24-70mm is affected by this issue to a greater degree).


Alternatively, do you mean thecolloquialdefinition, which is more formally known as distortion? Barrel distortion (straight lines bulge outward) commonly affects wide angle lenses (especially the wide end of zooms) and pincushion distortion (straight lines pinch inward) commonly affects the longer end of zooms. If that's what you mean, both the 17-55mm and the 24-105mm on a 1.6x body show some barrel distortion at the wide end, and the degree is similar (1.8% for the 24-105mm, 2% for the 17-55mm). That's noticeable, but nothing like the 24-105mm on FF (4.3% barrel distortion at 24mm; the L lens benefits from the 'sweet spot' effect when used on a crop body).



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Quote Originally Posted by nvitalephotography
Im looking at buying one of these two lenses with the main purpose being to do wedding photography.I have multiple lenses to use. My question, however, is, if you could only use one of these two lenses to shoot a wedding which would it be?

My answer to that would be the 17-55mm. IMO, it's the best general purpose zoom lens for a crop body.


But I think it's a bit unfair to consider the issue in isolation. Which other lenses do you have? For example, if the longest lens in your kit is 50mm, and you have a fast, wide prime, then you may benefit from the extra focal length of the 24-105mm and be willing to take the hit on aperture. Conversely, if you have nothing wider than 28mm (or your only lens wider is the 18-55mm kit lens), then you'll definitely need the wide end of the 17-55mm. Do you also have a second body? There's not always time enough to change a lens, and having a backup is critical in case of equipment failure.


On a broader issue, you state in your profile, "I am starting to explore the idea of wedding photography, with the hopes of becoming a semi-professional photographer." Hopefully, you're not planning to mount a new 17-55mm on your camera and head off to shoot a wedding. []


Check out Roger's (lensrentals.com) acronym-filled article on the subject - a bit tongue-in-cheek but he makes several good points.
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