Well, I thought it was cheap, so...

[Chris__R]

Leitz NPL Fluotar 50x/1.00 oel 160/-
It's gooey with oil; an ebay novice was evidently breaking up an Ortholux.
My only Leitz frame is an HM-pol, which is a 170 TL
I understand that means the tube length error, when used with a "170" eyepiece which I have, is only about 2mm.

A) is that right?
B) Would you expect it to make a noticeable difference? I know it's NA dependent. I don't have much to compare it with.
His pic:

50xOEL+Fluotar.jpg (84.1 KiB) Viewed 1688 times

[MichaelG.]

This should help, Chris
http://www.microscopy-uk.org.uk/mag/art ... on%201.pdf

For objectives with a magnification larger than 1:16, the 2 mm displacement of the intermediary image has no noticeable effect on image quality.

... and it’s worth getting the Leitz memo which is referenced.

MichaelG.

[MicroBob]

Hi Chris, nice objective!
A) yes
B) When Leitz sais its no problem this will be true. I have a Leitz 22:1 oil/water immersion Apo from the 37mm era. Used on a Zeiss Phomi with an 8mm spacer I'm 8mm away from the design spec. But it works absolutely fine!

This 50:1 was mainly intended for uncovered slides like blood smears. The working distance when used with cover slip is quite narrow so you should make sure not to use it with cover slips over 0,17mm or shoddy preparations with objects in various heights in the mountin medium.
The performance in very good and it is ideal for bigger diatoms and scanning through strew slides. N.a. 1,0 doesn't sound like much but this objective really resolves well. It is very useful to have oil immersion objectives of less than 100:1 to avoid oil/dry combinations. I have a nosepiece just for oil immersion objectives - very handy.

Bob