Orthoplan - Alternative Phaco and other Objectives with 0.90 NA Condenser

[Nicksmith]

Hi Guys few questions as I get to grip with my Leitz Orthoplan...

I have an 0.90 NA 402a Achromatic condenser, with Phaco positions "DF",1,2,3 are all full. Position "H" and one other with centering adjusters remain empty. It has a swing out top with no threads on it so I don't think tops are interchangeable. Also just to mention there is a coated convex lens installed under the iris which may be non-standard as I cannot see it in any pictures of 402a's on eBay (not that there are many, and detailed photos of Leitz Orthoplan parts are few on the web).

So my questions are:

1) For phase contrast, can use other 160mm Phaco objectives with my 402a, because it is hard to find any original Leitz 170mm Phaco objectives in the magnifications I want which are under 40x.

2) Luckily I do have the Phaco 40/0.65 170/.17 already, which is pretty sharp and very good for visual use in fact. But I want better than Achromatic colour correction if possible, say semi APO, FL or dare I say APO, if such a thing even exists? Higher NA wouldn't go amiss either. Suggestions would be great!

3) If I use a normal 1.3 NA objective either oil or air, is it really worth bothering with, seeing my condenser is limited to 0.90 NA, plus I think non-immersion, and in any case, I cannot find any higher original Leitz NA condenser? I gather condenser tops can be swapped but that sounds complicated as mine doesn't have any threads and I suspect this lower lens wouldn't work with a 3rd party top anyway, so maybe it's better to get a different compatible Leitz condenser or modify one from another manufacturer with an adapter plate or something. Your thoughts appreciated.

4) I do have an original Leitz PL APO 100/1.32 Oil objective with 1.25 NA. Can I use that with water or will it be a corrosion or coating nightmare, and if I do use oil or water on the slide only, would there be any real benefit, considering the condenser is limited to .90 NA and doesn't itself have an oil immersion top?

Many thanks for any insight and comments. I am enjoying the scope a lot and just want to see what more I can do with it for imaging. I will post imaging questions and cleaning questions separately

[PeteM]

1) I have a 402a condenser and use it with Leitz Phaco 160mm objectives. Could be the annuli in yours are different, but I suspect the 160mm tube length phase objectives will work.

2) A plain (not phase) fluorite or apo objective might be what you look for in a next lens. Not sure phase contrast images will benefit all that much from apo construction; given the "halo" you'll get regardless. Leitz made a number of 160mm fluorite objectives that show up now and then, used, at reasonable prices.

3) I'd try oiling your .90 condenser and observe the effect. Wouldn't be surprised if it helps a bit with your 100x.

4) Not sure what you mean by a 1.32 100x objective with 1.25 NA. In any case, wouldn't try using your 100x oil objective dipping into water. It most definitely does want oil immersion between the objective and cover slip -- and (#3 above) perhaps between the bottom of the slide and the condenser.

[Nicksmith]

1) I have a 402a condenser and use it with Leitz Phaco 160mm objectives. Could be the annuli in yours are different, but I suspect the 160mm tube length phase objectives will work.

2) A plain (not phase) fluorite or apo objective might be what you look for in a next lens. Not sure phase contrast images will benefit all that much from apo construction; given the "halo" you'll get regardless. Leitz made a number of 160mm fluorite objectives that show up now and then, used, at reasonable prices.

3) I'd try oiling your .90 condenser and observe the effect. Wouldn't be surprised if it helps a bit with your 100x.

4) Not sure what you mean by a 1.32 100x objective with 1.25 NA. In any case, wouldn't try using your 100x oil objective dipping into water. It most definitely does want oil immersion between the objective and cover slip -- and (#3 above) perhaps between the bottom of the slide and the condenser.

Thanks Pete, I'll experiment with the oil. I didn't know if the 402a could be oiled as it looks like the oil could drop into the lens beneath the swing out condenser. Does anyone know the oil spec to use?

That was a typo I meant 1.32 NA.

The Phase images can definitely be better colour corrected as the halos tend to split red/blue but I guess if there isn't a better corrected Phase objective, I can process that out. It is actually quite sharp.

I have the 40x/0.75 PL APO already, and the 25x/0.65 PL APO, but I think I will look for some Phase contrast objectives if I can find them, I guess they should at least be Leitz brand to work with the eyepieces.