long working distance objectives- worth it?

[pinkbeetle]

Ok last question on outfitting my Leica DMRB- are long working distance objectives worth it for higher mags? Trying to decide between these two lenses, one of which is not quite meant for my setup, but is long working distance. I’m thinking the increased amount of the sample in focus would be really nice at higher mag. I’m imaging plankton mostly, and would like to use DIC and darkfield. Which lens would be better to capture plankton?

[Alexander]

The L40/0.60 is nothing you want on your DRMB. It is designed to look through the bottom of Petri dishes. The correction collar is from 0 - 2 mm. Imagine the fiddling to set it properly to 0.17 mm.

[pinkbeetle]

Thanks! Yea I was hoping to get LWD but doesn’t look like it’s going to work out. That’s ok though.

[apochronaut]

I use what is likely an ancestor to the 40X 0.75 Fluotar fairly regularly. If it isn't , Leica would have used it as a prototype, if they didn't think they could make something even better otherwise, so the HCX 40X 0.75 Fluotar is probably at least as good as what I am using and notable due to W.D. My Reichert 40X .70 Planfluor is one of my favourite objectives to use, mainly due to it's ease of use. The W.D. at .48 is just about the same as an average 40X achromat and is in fact more than my 25X .65 planapo, so pretty good. The HCX is a little tighter at .40 but then that is still the same as the current generation of a Leica 40X planachros. Some are even less. Any time you can get a fluorite class objective with a working distance the same or better than an achromat, that is a big plus. I've also found the 40X .70 Planfluor to be very accepting of thicker than desired fresh mounts and a fairly deep viewing objective. It is a real high performance go to objective. Excellent DF objective.

I've posted quite a few images taken through that objective back some years now in both BF and DF , a lot from a certain creek I was surveying. Look up the word "fertile creek" in the search and that should find some, if you are interested.
I also use a phase version of that objective and just posted some images through it. The last 7 images are the 40X .70 Planfluor. Note the depth of field.

viewtopic.php?f=6&t=19862

[pinkbeetle]

Seeing this just now- thanks!