Does the Olympus BH2 phase contrast condenser provide darkfield?

[Ryanb]

My question is essentially the title. I've got the amscope darkfield dry condenser I use with my olympus BH2 but I am not a huge fan of it as it is not as dark as I'd like it to be. Anyone know if the phase contrast condenser for the bh2 has a darkfield stop or how I could improve the darkness my current condenser provides?

Thanks so much!

[josmann]

It does - up to lenses with an NA of .70, but I don't think it's any darker than the amscope condenser (which I also have but disassembled for this mod). It's more of a dark gray, as you describe. In my experience, this is more than enough to totally black out the background in post if you're doing photo or video work. Maybe you can get a little more darkness by widening the patch stop a bit?

For properly dark blacks you'll want an oil-immersion DF condenser. I use an Amscope model with the Olympus-compatible dovetail on mine. That's very dark although it does illuminate things somewhat differently than dry darkfield. Moreover, you have to deal with oil, which is a pain and never ceases to get everywhere.

[carlh6902]

There were two specific versions of the phase-contrast condenser offered by Olympus, for the BH2 scopes, as follows:

1) BH2-PC. This condenser has 0 (brightfield), 10, 20, 40, and 100 (phase) positions.
2) BH2-PCD. This condenser has 0 (brightfield), 10, 40, and 100 (phase) positions, and a dedicated darkfield (simple stop) position.

Of the two, I strongly recommend the BH2-PC. Why give up the ability to do phase contrast on a 20x objective, for simple darkfield?

For simple darkfield, this will work:

https://drive.google.com/drive/folders/ ... drive_link

Carl