In article <3331bcfd.12992706@nntpserver.swip.net>, i96henel@island.liu.se says...
>On Thu, 20 Mar 1997 12:07:49 -0800, Jim wrote:

>>I don't know about this, but at 1:1(or at same magnification ratio),
>>isn't that 200mm gonna have much shorter DOF?
>>And at 1:1, 60mm is about 2.5cm from the tip of the lens barrel to the
>>subject, 105mm somewhere around 7cm from the subject, there is a
>>"significant" working distance, but does it really matter? I think the
>>kind of subject that you want to shoot determines which focal length to
>>get. Also the 200mmf4 macro is real expensive.....

>Uh-uh...
>
>In macro the DOF is a function of magnification. The DOF with a 200 at
>1:1 will be the same as 60 at 1:1 at similar apertures.
>
>Working distances, AF version. (from front-element)
>
>60 mm - 72.9 mm
>105 mm - 136 mm
>200 mm - 245 mm (don't remember the exact figure)
>
>Also to consider, the 60 is flat-field which the 105 and 200 aren't!

Hmmmmmmmmm......., I would be VERY surprised to find a current Nikkor
macro not flat-field in the macro range... (though the 55 f3.5 was
sometimes not flat-field, noticeable near infinity-focus...). A quick
way to check: shoot a FLAT newspaper page with fine print at a 45 degree
angle, running the line of sharp focus diagonally across the frame from
one corner to the opposite corner. Check the negative (or a print - OK,
since the line is in the center, removing other modes of introducing
linear distortion ['less the photo paper is not flat...;-]) for the straightness of the line of sharpness. Since all of the Micro-Nikkors
are essentially "loating-element" designs now, it would seem easy to
design for field flatness (a basic quality of macro lenses...).
Hope This Helps