Olympus DCD darkfield condenser: please assist on how to use it

[deBult]

Hi,

I have been using a dark field stop on my Olympus CH2 (nice for looking at Anne's diatoms and protozoa).

I have bumped into a deal that as a bonus contained a dedicated Olympus darkfield condenser for my BH2: the DCD na 0.92-0.8.

If I recollect correctly the na of an objective needs to be less/lower than the one of the condenser?
The condenser is still in international mail and may take a few weeks to arrive due to C. postage delay.

Can you please guide me on how to use this condenser please, for a start the RANGE in na  numbers confuses me.
(note: reading the German language is OK for me, writing is a different matter though)

[Rawfoto]

Good Morning

Condenser is for dry use, can be used with LB lenses or on BX series. It has to be positioned exact in the center and it needs objektives with internal iris to work best. E.g. D-Plan 50 (Oel to be used on lense side),  S-Plan 100 dry are constructed for this condenser . It is working with higher NA top, of the iris is reducing the light path.
You easy can see the right position by turning the iris. I used it on BH-2 mainly with D-Plan 50 and S-Plan 100 dry.

If you do have the Oel condenser too you will not use this one not very often.

For low NA Simply DF Adapters are delivered from Olympus. They are simply metal plates. The lenses can be used with this condenser too.

Greetings

Gerhard

[smashIt]

for a start the RANGE in na  numbers confuses me.

the condenser produces a hollow cone of light with an inner nA of 0.8 and an outer nA of 0.92.
the lens you want to use has to have an nA lower than 0.8.

[deBult]

Tnx guys for quick response,

Gerhard: I have the LB DPlan 50 oil with Iris, only the dry version of this condenser though.

Chris: the inner - outer cone clarification helps a lot

Expect to increase the cleaning effort in preparing slides 

Best, Maarten