Two questions regarding water immersion

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ldflan
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Re: Two questions regarding water immersion

#31 Post by ldflan » Wed Dec 28, 2022 3:15 pm

apochronaut wrote:
Sun Dec 25, 2022 5:49 pm
ldflan wrote:
Thu Dec 22, 2022 4:30 pm
... AO Biostar 1820s on eBay equipped with very high quality Leica LWD infinity-corrected phase contrast objectives with adjusting collars and matched condensers.
I was just going by your high praise of the Leica objectives on those cheap Biostars. Now I see that the barrels are cheap and the paint wore away.

I owned a Biostar once but it had the lousy AO objectives in it. Where were those high quality Leica objectives when I needed them? I wish you had been around 5 years ago to point the way . I would have sent you a bottle of Dom Perignon as a thanks.
WA Butter is a former AO, Reichert, Leica authorized dealer and factory service provider.
As I said, Snidely, the Leica LWD objectives are indeed high quality. They are LWD objectives, so that is a compromise out the gate, of course. Optical quality does not depend on the paint job, duh. The barrels could be better, but even a cheap Lomo aluminum barrel will perform will if it was built right and not abused. As I said, in comparison to other LWD objectives of the time, they hold up fine. I don't know what lousy objectives your Biostar had. Don't you? If you don't know, why are you trash talking them?

But again the point here is that one can get a good inverted scope for next to nothing and it will admirably serve the OP's purpose. There are now two data points on the 1820. Your uninformed condemnation of the scope without remembering what objectives you had on it (and I don't even believe you), and my recommendation that for $200 you can't really go wrong for a scope that does what the original poster is trying to accomplish. What you are trying to accomplish here, I am not entirely clear.

ldflan
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Re: Two questions regarding water immersion

#32 Post by ldflan » Wed Dec 28, 2022 3:41 pm

"As a stop gap measure the Buffalo factory may have relabeled these objectives with the Leica brand. As noted this was a stop gap effort and the branding was painted on rather than etched into the objective barrel. Yes, the labelling would wear off. The product life cycle in this configuration was so short lived that we never had a demo unit in our office configured this way."

Wow, great information! Thanks! If I understand you, then, the Leica branded LWD objectives on the late model Biostar were indeed relabeled AO designs, essentially brought under the Leica mark?

BTW, it's not that difficult on the 1820 to adjust the stage position to a greater distance from the objective turret if the short parfocal length is a concern. The prior owner of mine had used stacks of glass slides under the edges. Worked so well I forget they were there when I sold it. I never tried using infinity corrected LWD objectives from another manufacturer on it, but it seems likely it could be made to work.

Comments from the peanut gallery aside, the other downside of the 1820 (other than the fiddly phase contrast condenser) is that it would be pretty difficult to adapt it to LED lighting.

apochronaut
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Re: Two questions regarding water immersion

#33 Post by apochronaut » Thu Dec 29, 2022 3:34 pm

More comments from the peanut gallery.

I thnk you need to read the other comments more carefully, to fully understand the implications of them. It seems you have lost the thread of the discussion a little along the way.

The fact is that there is nothing cheap ahout the AO objective barrels, determined by actually having disassembled them in order to clean oil from the optical stack, instead of just staring at them and determining that they are cheap.

The fact that an objective is infinity corrected does not mean you can use it on any other infinity corrected ,microscope . You will get an image yes but the telan lens corrections, reference length and eyepiece corrections are all going to be slightly different. In the case of the 34mm parfocal AO infinity corrected system, a lot different, so an objective swap is not possible without a considerable amount of other conversions .
I still would like to know which mysterious Leica objectives were used in your mythical Biostar, not to mention which head and or eyepieces were used. It would need a Leica head as well and Leica eyepieces, otherwise there would be lateral ca.
Pictures would help. After all this forum is valuable as an educational tool. You never know when someone else might like to put objectives that are twice the original size with completely different optical corrections on their own Biostar, not to mention 30mm eyepieces. Pictures are worth a thousand words.

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MasLovesMicrobes
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Re: Two questions regarding water immersion

#34 Post by MasLovesMicrobes » Wed Mar 22, 2023 10:06 am

Hello, I just wanted to give a quick update regarding my eventual decision. I did end up getting a 60x UPlanSApo water immersion objective at a friendly price from a forum member. It was still a lot of money so I was dreading on it day and night for some weeks. I have been using it for over a month now and I could not be more impressed with the performance. Incredible resolution, color, corrections and indeed penetration depth. I can easily see 200 microns into a sample without significant loss of resolution or aberrations. This is the most important thing for me, I feel liberated from the confines of the top of the slide, feels like flying. So yes, very happy. I'm finally getting around to posting some of my pictures as well. See them also on photomacrography.net.

I just use the standard 0.9 dry top lens and it works very fine for me, even with 100x oil immersion I am impressed. Will eventually get 1.4 as well, and try water and oil immersed top lens. But I suspect it will be a lot of hassle to always exchange the two, I tend to switch objectives back and forth a lot.
Another small point that I like about the 60 over 40 is the increased optical slicing, due to the high NA. This might increase further with 1.4 top lens immersed

But for whoever is considering this objective, I would like to mention that in many situations my 40x dry UPlanFl is equally impressive and I find myself using it often just because it is that little bit more convenient. Similarly I've just started using my 100x (So I don't know the pitfalls yet) and am also just so impressed. From my photo's I find it hard to tell which one I used if I don't remember.

So yeah take away from this what you want. I'll maybe update this is a few months more when I'm more familiar still with all the intricacies. Note that for 40,60,100 I do all my observations in DIC, if you won't do DIC maybe this post applies less so to you.
Beauty lies not in the eye of the beholder, it lies in the lens of a microscope.

apochronaut
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Re: Two questions regarding water immersion

#35 Post by apochronaut » Wed Mar 22, 2023 1:16 pm

I see very good results in your other recent rotifer post.
Be careful using water as a condenser immersion. As zzffnn mentioned, water condensers are few. Actually, I don't know any, except for the one I ended up with while trying to make a Reichert 1.4 condenser for a Microstar/Diastar. I didn't design it that way, it just happens to work best with water, entirely by accident.
Your working N.A. using a dry condenser is about 1.2 with that objective and depending on whether the condenser is mfg. as a dry condenser or is an oil condenser used dry, there may be some added spherical aberration, which should be avoided when trying to optimize a high end objective. As the colour correction and N.A. of an objective increases, so do the demands on the condenser, otherwise the costly specifications of the objective diminish in value.

Major defects in a condenser that fits and works and is mechanically fit are : incorrect front focal length, too low an N.A, too high an N.A., too much spherical aberration, too much chromatic aberration, inadequate field coverage, incorrect back focal length. Usually, a condenser that originated as part of a microscope's original equipment doesn't suffer from too many of those or not to a degree that detracts from it's intended function but once you use it off spec., all of a sudden some of them can become evident, as evident as condenser defects can become. They are much more subtle than those of objectives and often are only perceivable by way of comparison. Poor condenser performance is often attributed to the objective or the system as a whole. It is hard to isolate but defective condenser performance is real and sometimes solveable, sometimes not.

It's not that easy to change an oil immersion condenser to a water immersion condenser. It can be done by altering the space relationships between the internal components, at least getting close to perfect anyway, but that is not a very practicle solution. Outside of that the only way to make an oil immersion condenser adjustment, in order to function as a water immersion condenser, is by changing the spatial relationships between the condenser and object plane. As thin as possible an immersion layer coupled to an increase in slide thickness will cover the bases but unfortunately, the chromatic aberration base and spherical aberration base are in different locations, so there is no one size that fits all. Choose your poison. Those two ills are much less evident with simple achromat systems and lower grade condensers (abbe) because they are already there but with better condensers and well corrected high N.A. objectives, they aren't supposed to be, so it turns out that even an abbe condenser when correctly set up and illuminated properly can be better than an achromat aplanat that is not. An unoiled achromat aplanat could easily be worse than an oiled abbe and when both are unoiled , there might be very little difference

What the condenser is trying to do is direct the photons in order to increase contrast and resolution. This is observable very easily in phase contrast where the objectives used can be exactly the same objectives used for the lowliest of bright field microscopy. In fact, some systems use student objectives, the very same objectives used in a public school microscope with the simplest abbe condenser, yet the revolution in contrast is such that a simple .65 N.A. achromat can resolve details as though it were a .85 objective with fluorite elements inside, resolving punctae on diatoms, when without the phase component, not even striae are evident. This is all done in the condensing system. Yes, there is an annulus in the objective but that is only for convenience. It can be removed to elsewhere and the objective left as a basic bright field achromat. The diaphragm, condenser and annulus act as a combined condensing system but must be critically aligned and focused in order to perform this miracle. This is just to illustrate how much the condenser can affect the whole when accurately conformed, or just as easily not, when innacurately conformed.

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Re: Two questions regarding water immersion

#36 Post by MasLovesMicrobes » Sun Mar 26, 2023 12:23 am

Okay wow, thanks apochronaut, you seem to know a lot about this. I'm not sure I can understand all of it but I'll keep what I can in mind.
Martin Kreutz, from https://www.mikroskopie-forum.de/ seems to get good results with water immersion on his U-TLO. But I'll have to take a closer look at his setup to know how he achieves this. I think his and mine are very similar though.
Beauty lies not in the eye of the beholder, it lies in the lens of a microscope.

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