Nikon objective PlanApo 40X 1.0

[Francisco]

An unusual objective:
Nikon PlanApo 40X 1.0 Oil- 160mm

[viktor j nilsson]

That's a nice one from the original CF series. Nikon never updated it (CFN) before going infinity.

Not for sale, is it?

[apochronaut]

That probably is quite a sweet piece of glass. N.A. 1.0 appears to be only obtainable with immersion. I see multiple .95 objectives but all 1.0 I have seen are oil. Did Nikon have a DF condenser that was high enough to use that with?

[Francisco]

That's a nice one from the original CF series. Nikon never updated it (CFN) before going infinity.

Not for sale, is it?

Thanks for the info.
No, it is not for sale at the moment.
Greetings

[Francisco]

That probably is quite a sweet piece of glass. N.A. 1.0 appears to be only obtainable with immersion. I see multiple .95 objectives but all 1.0 I have seen are oil. Did Nikon have a DF condenser that was high enough to use that with?

Thanks for the info.
I don't know if Nikon had such a condenser

[apochronaut]

I mention that as a curiousity because very high N.A. DF condensers are uncommon and by the era that Nikon made that objective, high N.A.well corrected objectives such as that one often had an iris, so they could be used for DF with a fairly convential oil cardioid condenser as a lower magnification companion to a 100X oil with iris. As it sits that objective is a prime candidate to be used in DF but the condenser would either have to be very high N.A. or the objective would need modification to be used with a standard one. This allows for a convenient high resolution oil immersion DF system. Maybe Nikon also offered it with an iris as well or perhaps a funnel stop was available?

The Reichert , Bausch & Lomb and AO equivalents( the companies I know most about) had different ways of handling this problem in that era and in general the problems associated with medium magnification planapos: small working distance, coverslip sensitivity and usefulness with others in the same series, which were usually immersion.
At Reichert, in the infinity system from 1972 on , they put iris diaphragms in all objectives over .75 N.A. if DF was part of the microscope's system. For the 160 mm objectives they still made for the Zetopan etc., they offered options in an iris type and a funnel stop too. The infinity 40X 1.0 oil or a very similar objective to yours, made between 1972 and about 2000 always had an iris.
At AO, they downgraded their .95 specification for a well corrected infinity 40X to first .85 in the 60's and then to .80 in 1985 but it was a planapo dry objective. Their oil offering that combined with a 100X oil with iris for DF stayed as a planachro, first .85 with an iris , then later reduced to a 50X .80 oil with no iris. The latter is not too far off the performance of a planfluorite.
At B & L they did not have a 40X planapo that I know of but they did have a 50X .80 oil planfluorite. Again, no iris required to combine into a high resolution DF system.

[Francisco]

I mention that as a curiousity because very high N.A. DF condensers are uncommon and by the era that Nikon made that objective, high N.A.well corrected objectives such as that one often had an iris, so they could be used for DF with a fairly convential oil cardioid condenser as a lower magnification companion to a 100X oil with iris. As it sits that objective is a prime candidate to be used in DF but the condenser would either have to be very high N.A. or the objective would need modification to be used with a standard one. This allows for a convenient high resolution oil immersion DF system. Maybe Nikon also offered it with an iris as well or perhaps a funnel stop was available?

The Reichert , Bausch & Lomb and AO equivalents( the companies I know most about) had different ways of handling this problem in that era and in general the problems associated with medium magnification planapos: small working distance, coverslip sensitivity and usefulness with others in the same series, which were usually immersion.
At Reichert, in the infinity system from 1972 on , they put iris diaphragms in all objectives over .75 N.A. if DF was part of the microscope's system. For the 160 mm objectives they still made for the Zetopan etc., they offered options in an iris type and a funnel stop too. The infinity 40X 1.0 oil or a very similar objective to yours, made between 1972 and about 2000 always had an iris.
At AO, they downgraded their .95 specification for a well corrected infinity 40X to first .85 in the 60's and then to .80 in 1985 but it was a planapo dry objective. Their oil offering that combined with a 100X oil with iris for DF stayed as a planachro, first .85 with an iris , then later reduced to a 50X .80 oil with no iris. The latter is not too far off the performance of a planfluorite.
At B & L they did not have a 40X planapo that I know of but they did have a 50X .80 oil planfluorite. Again, no iris required to combine into a high resolution DF system.

Thanks for the interesting information.
Nikon had a PlanApo 40X .95 dry. iris
Both objectives came in a Nikon Fluophot microscope that I acquired a long time ago with this condenser.