Re: Query: Longer working distance objectives?

From: Gary G (see.signature_at_bottom)
Date: 06/28/04 

Date: Mon, 28 Jun 2004 15:10:22 -0700

On Mon, 28 Jun 2004 17:57:51 +0100, Charlie+ <charlie@xxx.net> wrote:

>I wonder if any experts out there know if there are longer working
>distance objectives that were produced for 160mm tubelength
>microscopes in the 20x and 40x powers? And if so what I should look
>out for on Ebay etc in the way of makes and specific markings on the
>objectives.
>Presumably NA figure would be a tradeoff of some description on this
>type of lens? I also presume there is no work-around to get longer
>distance to subject from a standard 160 / - objective!?
>- TIA
>Charlie+

Yes, you can get long working distance objectives for 160 tube length.
They are available as NEO (reflected) or transmitted. Typically, the
objective will say "LWD." The working distance is usually two to
three times a non-LWD objective. The sacrifice is poor NA. For low
mag, not a big problem.

Why do you need longer WD?

Gary Gaugler, Ph.D.
Microtechnics, Inc.
Granite Bay, CA 95746
916.791.8191
gary@microtechnics dot com