Patrick Van Oostveldt wrote:

> Using confocal microscopy one of the limiting points is the working
> distance of the lens. This is engraved on the new Nikon lenses but not
> on other lenses.
> Does any one has experience of the practical measuring of working
> distances?
> If any body there givs me the information I will be glad to post a
> summary on this.

Dear Patrick--

My own very limited experience deals only with oil-immersion 60x 1.4 NA
objectives.  A few years ago, when manufacturers switched from 160 mm
tube-length optics to infinity optics, our department bought a new
microscope to mount under our new confocal.  I found that with the new
60x objective I was unable to image through the full thickness of tissue
sections that I had formerly been able to image with the comparable 60x
1.4 NA objective mounted on our older 160 mm tube-length scope.

Although the working distance for the new objective was listed as being
0.11 mm and that for the old objective was 0.12 mm, there was a 30+
micron difference in the depth to which we could focus.

Bottom line: the manufacturers should have the numbers.  However, don't
necessarily believe them.

Good luck!

Martin Wessendorf
--
Martin Wessendorf, Ph.D.                        office: (612) 626 0145
Associate Professor                             lab:    (612) 624 2991
Dept. Neuroscience                      Preferred FAX:  (612) 624 8118
University of Minnesota                 Dept FAX:       (612) 626 5009
Minneapolis, MN  55455                e-mail: [log in to unmask]