Views on comparison issues

Hi all I would like to know what peoples views are on comparing lenses of different focal lengths against each other for sharpness. Countyman and I have spent a bit of time recently comparing lenses to see what appears sharper to us under semi-controlled conditions, by that I mean on a tripod indoors same settings same subject.
Countyman might foot my a*** for me here but I think we are not comparing correctly.
My question is if we were testing for example a 17-55mm f2.8 IS lens with a 70-200mm f2.8 IS lens and a Sigma 120-300mm f2.8 lens on a tripod, should they all appear equaly sharp if say we were taking a shot and then moving the tripod so that the same magnification is achieved. What has happened is the 17-55 looks much sharper than the other 2 with the 70-200 in 2nd place and the 120-300 not looking to clever! Is this what you would expect or should they all appear to be equally sharp?
I appreciate in advance any comments, although Countyman might not
Cheers Ricky

I think this is a moot point. Take some test shots and if the lens is good, keep it.
If you find that the 17-55 is sharper at 17 than 120-300, then what? are you gonna shoot sports from the side lines with a 17mm lens? Comparaing similar lenses for difference in optics will give you information on which lens to choose, but 17-55 is not comparable lens to a telephoto and vice versa. The 70-200 and 120-300 is closer, but still with a bit of differnce.

Ideally you want to get sharp lenses at the focal lengths you shoot, so pick the lenses with the range you need and try to get ones in that focal range with good optics. Besides all this pixel peeping wil make you cross eyed or blind.

rickydiver wrote in post #2075103
Hi all I would like to know what peoples views are on comparing lenses of different focal lengths against each other for sharpness.

It would seem to me that a lens is chosen for use for a given picture on the basis of the camera position (i.e., magnification--focal length) and lighting it allows. Thus, I don't care if my short telephoto is much sharper than my wide angle, or vice versa, because one doesn't replace the other in application.

Thus, I compare lenses of similar focal lengths and application to each other, but not to lenses of other focal length and application (except for fun--not for choosing what to buy and use).

I have many times made images with wide-angle lenses of lesser image quality than longer lenses strictly because the wide-angle view was important to my composition. All it limits is the size print I can make (assuming my technique is better than what is needed to reach the lens's potential).

Rick "who uses lots of lenses thought inferior by equipment geeks" Denney

My EF-S 60 appears much sharper than my 400 f/5.6.
The only problem is that the little macro does not give me very sharp images of migrating birds in flight.