Condenser positionning

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smollerthings
Posts: 457
Joined: Thu Aug 19, 2021 12:10 pm

Condenser positionning

#1 Post by smollerthings » Sat Oct 16, 2021 9:19 am

Hi all,

Condensers are still very mysterious to me. I have been advised to leave them up, and I have done that with good results. However, I have noticed some condensers have lower mechanical positions compared to other. Some go up to the slide (Lomo for ex), some lie 2-3 mm below (Karl Kaps, phase contrast condenser).

Is there any reason for this difference in design?
Thanks!

MicroBob
Posts: 3154
Joined: Sun Dec 25, 2016 9:11 am
Location: Northern Germany

Re: Condenser positionning

#2 Post by MicroBob » Sat Oct 16, 2021 10:32 am

The condenser has to create a conical light beam. The bigger the included angle the more resolution is possible, high numeric aperture. Above n.a. 0,95 immersion is necessary. To use oil the gap has to be narrow. For a dry condenser below this n.a. the distance can vary, depending on the lens diameter. Your phase condenser is probably a n.a 0,9 dry condenser - right?

smollerthings
Posts: 457
Joined: Thu Aug 19, 2021 12:10 pm

Re: Condenser positionning

#3 Post by smollerthings » Sat Oct 16, 2021 11:16 am

Thanks for the explanation.

Nothing is written on the condenser but I think it is likely to be 0.9 dry.


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