Undecided . . .

[neuroanatomist]

Well, Raid, if you really want to get pedantic about it, focal length isthe physical distance which separates the rear nodal point of an infinity-focused lens from the image plane onto which the light passing through the lens is focused. Thus, focallength is an intrinsic property of a lens, and is unaffected by the mount format or the size of the sensor in the camera body to which the lens is attached. So, there is a 15mm gap in focal lengths between the 55mm long end of the 17-55mm and the 70mm wide end of the 70-200mm, because 70mm - 55mm = 15mm.


When you mount a 70-200mm lens on a crop body, photo elves do not magically transform it into a 112-320mm lens - the focal length remains 70-200mm, but you get the angles of view equivalent to a (hypothetical) 112-320mm lens on a FF camera. So, if you want to compare FF-equivalent angles of view, then Dr. Croubie is correct and there is a FF-equivalent gap of 24mm (i.e. the gap between 27-88mm and 112-320mm). It's irrelevant that the EF-S 17-55mm cannot mount on a FF camera, since when mounted on a crop body, it yields angles of view equivalent to a (hypothetical) 27-88mm lens on a FF camera.


Raid, it occurs to me that you might have a misconception about EF-S lenses (a fairly common one), that because they mount only to APS-C bodies, their focal lengths are 'corrected' for the APS-C sensor format, such that 55mm on an EF-S lens optically different from 55mm on an EF lens, so that the former gives the same angle of view on APS-C as the latter on FF. But, that's not the case - 55mm is 55mm, regardless of camera or mount format - it just results in a narrower angle of view on an APS-C camera.


So, my original statement, that the 17-55mm + 70-200mm provides coverage from 17-200mm with a 15mm gap, is technically correct. Since the OP has an APS-C camera, that statement could also be phrased as FF-equivalent coverge from 27-320mm with a 24mm gap.

[Rocco]

Raid, it occurs to me that you might have a misconception about EF-S lenses (a fairly common one), that because they mount only to APS-C bodies, their focal lengths are 'corrected' for the APS-C sensor format, such 55mm on an EF-S lens somehow different from 55mm on an EF lens, such that the former gives the same angle of view on APS-C as the latter on FF. But, that's not the case - 55mm is 55mm, regardless of camera or mount format - it just results in a narrower angle of view on an APS-C camera.


So, my original statement, that the 17-55mm + 70-200mm provides coverage from 17-200mm with a 15mm gap, is technically correct. Since the OP has an APS-C camera, that statement could also be phrased as FF-equivalent coverge from 27-320mm with a 24mm gap.

Well said.

[HDNitehawk]

photo elves do not magically transform it

Are you sure? I was checking B&H and it seems they are out of magic photo elves. Do you realize how much money I could save on equipment with these elves.


Larry


Neuro's advice for a second lens is sound, the 17-55mm should cover you well however, I have never owned that lens so my statement is based on the lenses reputation.


I have owned these though:The 70-200mm II L that you have is an awesome lens and puts out very good quality. I am less of a fan of the 24-70mm and 24-105mm, I do not feel they match the quality of the 70-200mm, although they are very good lenses. My opinion is that the 16-35mm L II is a better lens than those two. Personally I cover the the short side of my kit with a 24mm and 35mm L andhardly everfind myself wanting a short zoom. ( I should qualify the statement, I haven't found any canon zoom that will match the 70-200mm II)


Good Luck.

[HDNitehawk]

Now there's a test, has anyone tried doing it? take an 85mm shot with a 15-85 lens, and a 55mm shot with the 17-55mm lens, crop it and scale it to same framing as the 85mm, which one is better?

Yesthere hasDr, onlyI haven't seen one specificalyusing 55mm and 85mm it was other focal lengths,andtests with diffrentbodies.There was a test of the7d and 5d with different focal lengths to take the same area. There are allot of variables in this. Are you going to compare the 85mm L or the 70-200m L at 85mm compared to a cropped 17-55mm? Of course you realize that there are amultiple different ways to test this. Body vs Body, Lens vs Lens and an what seems like a long list of different combinations.


From all the other tests I have seen performed on other lenses, I would bet on the 85mm lens rather than the crop.

[neuroanatomist]

Now there's a test, has anyone tried doing it? take an 85mm shot with a 15-85 lens, and a 55mm shot with the 17-55mm lens, crop it and scale it to same framing as the 85mm, which one is better?

Yesthere hasDr, onlyI haven't seen one specificalyusing 55mm and 85mm it was other focal lengths,andtests with diffrentbodies.There was a test of the7d and 5d with different focal lengths to take the same area. There are allot of variables in this. Are you going to compare the 85mm L or the 70-200m L at 85mm compared to a cropped 17-55mm? Of course you realize that there are amultiple different ways to test this. Body vs Body, Lens vs Lens and an what seems like a long list of different combinations.

I assume he meant same body - "85mm shot with a 15-85 lens, and a 55mm shot with the 17-55mm lens" means EF-S lenses based on those zoom ranges, i.e. taking a shot at 55mm on the 17-55mm and cropping it to the framing of 85mm on the 15-85mm. I haven't seen that done, but I'm sure that the native 85mm image would turn out better than the cropped 55mm image. Of course, the OP has the 70-200mm II, which will outperform the 15-85mm in the overlapping part of the range (now, is that a 15mm overlap or a 24mm overlap??), plus be 2 stops faster.

[Dr Croubie]

well i was specifically targetting the efs 17-55 f/2.8 vs the efs 15-85 (on the same camera), as they are the two lenses that get most recommended for APS-C cameras on almost every

[HDNitehawk]

Dr.


Most of the tests I have seen the crop usually looses. But it is a good question. I would bet a few dollars against the croped image. The 70-200mm at 85mm will beat them all.


I think a better comparison would be if you could improve the quality in the 17-55mm range vs the 15-85mm, and live with a little less quality if you had to crop.








Now, all of you are only partially right. It is a 19.5 mm difference on my Mark IV [:P]

[HDNitehawk]

[View:http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=398&Camera=474&Sample=0&am p;FLI=4&API=2&LensComp=675&CameraComp= 474&SampleComp=0&FLIComp=3&APIComp=2]


At comparable focal lengths, I wouldn't really say the 17-55mm beats the 15-85mm at the same distance.

[Kayaker72]

Well, there are ample comparisons (this site, photozone.de, and slrgear.com) for an uncropped comparison of the EFS 15-85 @ 85 mm and the EFS 17-55 @ 55 mm. My quick take, the 15-85 wins in the center by a little and loses at the edges. You start cropping, it will only become worse, and you actually will lose the edge advantage. Opitically, everything I've seen tells me these lenses are very similar. I'll even conceded that looking at all overlapping focal lengths the 17-55 might be a bit better, but not by much, and it really goes back and forth depending upon the focal length. The real difference is the aperture vs the focal length range.


Edit--[]...looks like Rick and I were looking up the same thing at basically the same time..........


http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=675&Camera=474&Sample=0&am p;FLI=5&API=1&LensComp=398&CameraComp= 474&SampleComp=0&FLIComp=4&APIComp=2

[Dr Croubie]

yeah, i reckon the 15-85 @ 85mm probably would beat a cropped shot, i should have added that i was looking at the edge resolutions when i said it fell apart a bit, the centres are just great the whole way along.


still, it'd be an interesting test, if anyone's got one of each.


(edit, ooh, i just realised, i know someone with a 17-55 f/2.8. on her 1000D. (still, it's better than a 7D with 18-55 non-IS). doubt i could borrow it for a test though.)


.


hmmm, meanwhile, so what happens if i attach my MIR-3 65mm lens to my 7D? it's a wide angle lens when it's on my Pentacon Six, do the lens elves turn it into a wide-angle on my APS-C? or is it a 200mm telephoto? if i put it on a shift adapter for +12mm shift, is it a 77mm lens? :P :P :P :P