Strange Bedfellows

Everything relating to microscopy hardware: Objectives, eyepieces, lamps and more.
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apochronaut
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Strange Bedfellows

#1 Post by apochronaut » Fri Jul 16, 2021 11:09 am

I have read from several users that Nikon 160mm D.I.N. objectives work well on an infinity corrected AO/Reichert series 400 scope. This always seemed odd to me but one of the reports came from someone that I have no reason to doubt and the particular objective was used for 20X D.I.C. too.
I should have tried this out while I had Seta's 60X Nikon planapo here for repair but the idea only ocurred to me after I had packed it for return.
Recently, an ebay merchant in Japan has been offering both Nikon and Olympus 160 D.I.N. objectives at quite low prices. One popped up, a uvF 100X 1.30 w./iris glyc. for a really low price , so I figured for under 100.00 shipping in, I couldn't go wrong. The fact that it was glycerin immersion was even better because I have this lone Reichert 63X 1.0 oo glyz. that although it is a 63X and 1.0, is a bit of a pain due to it's mismatch with every other objective I have for the system, except dry ones. I even have a restrictor rear diaphragm for it that I pilfered from a broken 100X of the same series so I can use it for DF at about .85. Having a 100X glycerin immersion to go along with it and with an iris diaphragm for DF seemed promising. Well, you know what? That Nikon 160mm objective works really well. It works best with the blue filter swung in for sure and magnifies about 110X in the system but there is nothing shabby about it's performance. It isn't plan but it is a fairly flat field objective, so that aspect of it is barely noticeable. The parfocality with the Reichert 63X is slightly off but nothing a few parfocalizing shims won't cure and the glycerin immersion is very nice.
I did a comparison between it and the standard 100X 1.25 planachro oil immersion from the Buffalo plant. The image quality is very similar with the planachro having just a slight resolution edge close to the periphery of a 20mm field , likely due to the Nikon not being plan but the image sharpness overall and ca correction is about equivalent. I have yet to trial it for DF.
I don't know how this fares for other 160mm Nikon objectives used in that system. No doubt they are best in their native system but if an attractive price on an attractive objective came along, it might be worth a try. Nikon is highly resaleable so it is hard to lose.

One note is that in the Microstar/Diastar the Reichert Austria objectives have a very slight lateral ca. It is almost imperceptible but cameras pick it up worse. This is cured by swapping to #145 eyepieces, which are slightly compensating. It appears that both the Reichert objectives and the 160 NIkons need about the same degree of compensation.
Last edited by apochronaut on Fri Jul 30, 2021 12:48 am, edited 1 time in total.

Scarodactyl
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Re: Strange Bedfellows

#2 Post by Scarodactyl » Fri Jul 16, 2021 10:09 pm

Huh, that's very cool! I wonder if the reverse works too.

hans
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Re: Strange Bedfellows

#3 Post by hans » Sun Jul 18, 2021 1:12 am

Interesting, do the Nikon heads for these objectives use prisms or mirrors?
apochronaut wrote:
Fri Jul 16, 2021 11:09 am
One note is that in the Microstar/Diastar the Reichert Austria objectives have a very slight lateral ca. It is almost imperceptible but cameras pick it up worse. This is cured by swapping to #145 eyepieces, which are slightly compensating. It appears that both the Reichert objectives and the 160 NIkons need about the same degree of compensation.
The Vienna objective patent Brian pointed out in this post says 1% lateral CA. So if the Nikons are close to neutral then the degree of mismatch should be similar but in opposite direction vs. the Vienna objectives when used with a 0.6% lateral CA Buffalo head? If that's the case and 145 eyepieces reduce overall lateral CA mismatch with Vienna objectives, then seems like they would make the mismatch worse with Nikon objectives since the eyepiece compensation would be going in the wrong direction relative to the objective/head mismatch?

apochronaut
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Re: Strange Bedfellows

#4 Post by apochronaut » Sun Jul 18, 2021 3:45 pm

[media][/media]
Scarodactyl wrote:
Fri Jul 16, 2021 10:09 pm
Huh, that's very cool! I wonder if the reverse works too.
One of the confusing things about this unusual coherence is that the 160mm objectives are not designed to require a telan lens. However, clearly the Austrian Reichert infinity objectives must have one in order to focus an image at the focal point of the eyepiece. It is a safe assumption that they would not work in a Nikon Labophot or some such microscope.
How does it work that the Nikon objective just happens to not be negatively affected by the presence of the telan lens, since it is not designed to need one? Well, it is affected by it but primarily by effectively lengthening it's tube length requirement to be about 20mm short of the systems total length( infinity space + reference length), a not particularly big issue. This means that it is functioning like an infinity corrected objective requiring a reference length of about 160mm, hence in the system it magnifies about 10% more or behaves like a 110X objective approximately.
What about corrections?
This is not a CF objective, so presumably, it requires either some compensation in the eyepiece or some correction. I don't have any Nikon eyepieces from it's era to determine which but in comparing it with the Reichert objectives, to which it is a close performance match tells me that it requires some compensation, since the Reichert objectives in combination with the Series 400 telan lens require a small degree of compensation. I don't know what role the telan lens plays in that but empirically, I see the compensation requirement of the total system and it happens that the slight amount of compensation designed into the 145 eyepieces fits it like a glove. It just so happens that the same degree of compensation or very close is required by the Nikon 160mm objective once it also passes it's image through the series 400 telan lens and optical windows in the head as well

viktor j nilsson
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Re: Strange Bedfellows

#5 Post by viktor j nilsson » Sun Jul 18, 2021 4:53 pm

Is it one like this?

Image

If it is, then it is definitely a CF objective.

hans
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Re: Strange Bedfellows

#6 Post by hans » Sun Jul 18, 2021 5:26 pm

What do Nikon non-CF DIN objectives look like? I thought you were talking about CF because you referenced Seta's CFN objective you repaired. I have two older non-CF Nikon objectives that came mismatched with some B&L stuff I bought, haven't tried them on anything yet, but these are JIS with shorter parfocal distance I think?
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apochronaut
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Re: Strange Bedfellows

#7 Post by apochronaut » Sun Jul 18, 2021 10:10 pm

The objective is the one that Viktor pictured. None of them have CF on the barrel that I have seen. Maybe later ones did. The literature promotes that idea but as an objective series, the CF series. I have no doubt that Nikon like other manufacturers has spent a good deal of money on improving the ca correction in their objectives.Part of that goal would be to even out the degree of ca across the field , so probably the term should more properly be lateral ca reduced or something like that. I get that the concept is freedom from off axis ca but clearly a CF plan achromat has ca, otherwise it wouldn't be an achromat, so the CF moniker is pretty much a marketing schtick. They can't be blamed for it, many companies seek to woo customers with false or misleading claims. Look at Volkswagen, probably the most celebrated bogus marketing hucksters of this century.
The CF eyepieces are compensating eyepieces. I have a Nikon 5X CF photo eyepiece in my hand right now. It is a compensating eyepiece. Compensating eyepieces are used to compensate for the overcorrection of lateral ca necessarily introduced in the process of correcting other aberrations, so the fact that they are not using neutral eyepieces with the CF objectives means that they are not perfectly corrected for ca, they are purposefully overcorrected. I tried this objective with neutral eyepieces and I get an undesirable level of inverted ca.

Anyway. The point was and still is that the objective works well along with Reichert Austria objectives in a series 400 microscope in concert with #145 compensating eyepieces.
Last edited by apochronaut on Sun Jul 18, 2021 10:28 pm, edited 1 time in total.

viktor j nilsson
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Re: Strange Bedfellows

#8 Post by viktor j nilsson » Sun Jul 18, 2021 10:24 pm

Nikon never made an objective that says CF or CFN on the barrel.

Scarodactyl
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Re: Strange Bedfellows

#9 Post by Scarodactyl » Sun Jul 18, 2021 10:49 pm

viktor j nilsson wrote:
Sun Jul 18, 2021 10:24 pm
Nikon never made an objective that says CF or CFN on the barrel.
The only ones I've seen are the 45mm parfocal infinity metallurgical objectives which were labelled cf plan/cf plan apo.

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