Re: Using darkfield stop in Zeiss phase condenser

On 18 mrt, 19:58, "Oncologists" <Oncologi...@xxxxxxx> wrote:
On 18 Mar, 13:46, "Kevin Cunningham" <sms...@xxxxxxxxxxxxxx> wrote:





"Oncologists" <Oncologi...@xxxxxxx> wrote in message

news:1174161224.370409.51020@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Lovely darkfield with the Ph3 plate and the x10 and x20 (non-phase)
objectives, but how do you use the built-in darkfield stop? Tried it
with all objectives, condenser positions, and top condenser lens on
and off. Dimfield, yes; darkfield not!
It's a big stop and looks as though it designed for x40. Don't want to
try oil in case it spoils the condenser lens. Anyone know how to use
this please? Thanks to all who have helped with my previous,often
crass, queries!, HJ

If the condenser is pancake with out a swing out lens using oil is fine, no
problems. If it is a swing out then swing the top lens out and that should
produce dry dark field. If it is an oil condenser then oil the top and that
should produce good dark field. Remember that you should have an adjustable
100X. You will need to have a 100X with about a 1.00 NA, adjustable 100X
were made to do that.

Thanks,

Kevin Cunningham
SMS

Thanks, Kevin,
It isn't a swing out lens type, it is a zeiss phase condenser with a
darkfield stop and an unscrewable lens on top of the condenser.
Removing the latter doesn't seem to do much, except to screw up the
phase. The darkfield stop position is marked 'D' on the condenser.
If anyone is interested, I posted a query about some strange
translucent phase plates on this condenser in addition to the standard
ones.It turns out that these are polarised, so that the the phase
plate is variable by altering a polariser on the Kohler illuminator.
this was used to gradually switch in phase illumination to identify
fluorescent organelles in phase contrast. Never seen it before, but it
seems to work pretty well....
Perhaps I'll just try just a tiny drop of oil......
hj- Tekst uit oorspronkelijk bericht niet weergeven -

- Tekst uit oorspronkelijk bericht weergeven -

glad you finally found out the usefulness of the translucent condenser
plates. With some extra experimenting you could get nice colour
effects in phasecontrast with this condenser, google 'colour phase
contrast', eg Spike Walker's ultraphot site shows this for this
condenser.

Of course you will need to immerse the toplens of the condenser if it
is above NA1.0.

Rene.

.

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