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<blockquote data-quote="skater" data-source="post: 502283" data-attributes="member: 19158">I wanted to answer this, but I hesitated because...I don't know the answer.&nbsp; I think there are a couple things going on.Most zoom lenses, especially the less expensive ones, change aperture as you change the focal length.&nbsp; Naturally, changing aperture means that the depth of field will change, so it might seem like the two are related.&nbsp; But, you can buy a lens that keeps the same aperture throughout the entire zoom range (picture me drooling over the f/2.8 80-200), so I'm guessing the depth of field in those would remain constant regardless of the focal length.&nbsp; But I don't know for sure.This is kind of what I was saying before:&nbsp; I always think of it as taking a picture of a long measuring tape stretching out in front of me.&nbsp; Some part of the tape will be in focus, and it might a full yard long, it might be most of the tape, or it could just be a few inches.&nbsp; The aperture controls which one of those it'll be.&nbsp; With my zoom lenses, that distance will change because the aperture changes as I zoom in and out.&nbsp; I don't know if the focal length alone (on a lens with a constant aperture) would change the depth of field too.</blockquote>

[QUOTE="skater, post: 502283, member: 19158"] I wanted to answer this, but I hesitated because...I don't know the answer. I think there are a couple things going on. Most zoom lenses, especially the less expensive ones, change aperture as you change the focal length. Naturally, changing aperture means that the depth of field will change, so it might seem like the two are related. But, you can buy a lens that keeps the same aperture throughout the entire zoom range (picture me drooling over the f/2.8 80-200), so I'm guessing the depth of field in those would remain constant regardless of the focal length. But I don't know for sure. This is kind of what I was saying before: I always think of it as taking a picture of a long measuring tape stretching out in front of me. Some part of the tape will be in focus, and it might a full yard long, it might be most of the tape, or it could just be a few inches. The aperture controls which one of those it'll be. With my zoom lenses, that distance will change because the aperture changes as I zoom in and out. I don't know if the focal length alone (on a lens with a constant aperture) would change the depth of field too. [/QUOTE]

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