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Darkfield using Olympus BH2/BHS

Posted: Wed May 22, 2019 6:07 pm
by sombre
Assistance please,
My microscope is an Olympus bh2/bhs and i should like to be able to view subjects in darkfield.
Unfortunately there is no filter holder beneath the condenser in which to place a darkfield patch stop.
Does anyone know a way in which i can work round this problem, or if there is an attachment or
alternative condenser i could get. If so please let me know.
I have spent countless hours searching the net for some kind of fix, but to no avail, I would therefore be most grateful for
any advice.

Many thanks,

Re: Darkfield using Olympus BH2/BHS

Posted: Wed May 22, 2019 7:50 pm
by admin

1. Check if the condenser has a push on filter holder (and not a swing out type). The filter holder sometimes contains a blue glass filter. The patch stop goes on top of the blue glass.
2. If you do not have a filter holder at all, then make yourself a patch stop using overhead foil. Tape it there where the filter holder should go.

What about these: ... SwhzhcUi4h ... SwqURatO8G ... SwFZtbRmLH

Maybe this one also fits, becasue it has 37mm: ... 0005.m1851


Re: Darkfield using Olympus BH2/BHS

Posted: Thu May 23, 2019 12:09 pm
by PrecisionInstruments
The BH2 (BHT, BHTU, BHS) had either a dedicated Darkfeild condenser, or a dark field ring incorporated in the phase condenser turret. These would fit into the position where your current condenser is. I believe the condensers in the links or above post would not be compatible with your microscope.

Re: Darkfield using Olympus BH2/BHS

Posted: Thu May 23, 2019 12:35 pm
by Hobbyst46
A dedicated darkfield and/or phase contrast condenser is best, yet sometimes expensive and rare. A phase condenser offers more options and is preferrable IMO. Although it does not give DF with objectives of NA>1.

A year ago I faced a similar problem. Black patch circles, like Rhinebergs and black arrows failed to give DF on my scope. So I DIY'd two LED ring substitutes.

An adventure. Here is the link.
There are two gadgets: LED ring and LED strip. The latter is harder to make and, for me, was not as satisfactory. So I would start with the former. Both were inspired by scientific articles...

Re: Darkfield using Olympus BH2/BHS

Posted: Fri May 24, 2019 9:36 am
by sombre
Many thanks to all for the help and suggestions.
I think I will go down the diy route until such times as I can find the correct condenser etc:
Again many thanks.


Re: Darkfield using Olympus BH2/BHS

Posted: Wed Jun 05, 2019 10:00 pm
by Crusty
I just purchased this everything (oblique, darkfield, polarizing, Rheinberg) kit specifically for BH2's. I've only been playing with it for a few days, but I'd delighted with it. ... 2749.l2649