Breaking the baffling B & L Balplan buffalo.

[Scarodactyl]

What is the overall focal lebgth of the lens? It might be interesting to experiment with a normal achromat to get a sense of how vital corrections are--not volunteering to do it myself though, not right now anyway.

I think someone tried that a while ago.

The only example I've seen was with a microzoom 50x (the fancy type wirh the iris and longer working distance) https://www.photomacrography.net/forum/ ... 7&start=15
Results were surprisingly good all things considered, with a single tube lens and no corrections (perhaps just grabbing the center?). Of course the microzoom might look like a balplan and work broadly like one but that doesn't mean their corrections are the same.

[BramHuntingNematodes]

I love that guy's lighting setup with the busted out spray paint top.

[microb]

It is item 21 but in figure 2 of the 481665 patent. The specifications are from line 30 on page 4 to the middle of page 5.
I don't think the doublet would involve a crown glass element. Both n's are high, with fairly low abbe #'s.
According to charts, the double convex element would be something like a Barium Titanate glass and the double concave element something like a Barium dense flint.

Sorry, you're right I meant that patent 21 but in figure 2 of the 481665. So I edit with note my post above.