Re: Zeiss objectives - which oculars
- From: David Littlewood <david@xxxxxxxxxxxxxxxxxx>
- Date: Thu, 24 Nov 2005 12:01:56 +0000
In article <4384e59a$0$22346$9b536df3@xxxxxxxxxx>, Trond Kvitvik <dnort.kivtivk@xxxxxxxxxxxxxxx> writes
I think you are going to have more serious problems than which eyepiece to use. The lenses appear to be a mixture of infinity corrected and finite tube length objectives. I also don't think they are all Zeiss, but I'm not that familiar with Zeiss infinity corrected objectives.The Zeiss objectives on this link;
http://home.no.net/tkvitvik/images/sixzeiss.jpg
1,25x/0,033 Plan-Neofluar 2,5x/0,075 Plan-Neofluar 40x/0,70? NPL Fluotar 63x/1,40 Plan-Apo 100x/1,25 F 100x/1,32 NPL Fluotar,
could they be used on a Reichert Zetopan, provided I got the necessary (Zeiss) oculars, and in that case which type of oculars.
The lenses i mostly need myself are the low-power 1,25x & 2,5x ones, I guess they would be more forgiving on a 'wrong' scope than high power & high na, am I right?
An alternative would be a find an older & 'cheap' Zeiss stand, and to find suitable 10x & 20X to complete the setup. Which stand would then fit?
Please also comment on the lenses, not sure about the meaning of NPL, F, or Fluotar.
The 1.25 and 2.5x Plan-Neofluars at the left appear to be modern Zeiss infinity objectives.
The 63x NA 1.4 Planapo (top centre) also appears to be a modern infinity objective, and if it is in perfect condition could be worth more than many peoples' entire outfits (the last full list price for the 160mm tube length version was almost £3,000 (about $5,000) in the UK.
The 100x NA 1.25 is an F-Achromat from (I would estimate) the mid-1980s. It will say something like 160/- on the side not visible in your photo, indicating it is designed for use in a 160mm tube length microscope. This was the standard until infinity corrected scopes became the norm from (IIRC) late 1980s onward.
The two bottom right lenses, the "Plan-Fluotars", are almost certainly not even Zeiss lenses; I claim no comprehensive expertise, but I don't recall Zeiss making objectives of this name. They are also clearly marked as for 170 mm tube length microscopes, and I don't recall Zeiss making these at least in post-WWII times. At a guess (and I'm really outside my area here) they may be Leitz lenses. If so, then the tube length difference may be more apparent than real, since IIRC Leitz had practice of measuring tube length to a different point from that used by everyone else, which meant the true difference was quite small. However, I could be wrong here as I'm certainly no Leitz expert.
I'm not entirely sure what will happen if you use the wrong tube length. The effect is to wreck the correction for spherical aberration, which is specifically optimised for a single tube length. How bad the effect is will depend on the objective; it will probably be worst for the high magnification, high NA objectives. I was about to suggest you try the low-power objectives on a "wrong" scope and see, but on closer inspection I see that the infinity objectives have a wider mounting thread, so you can't. Another reason why the two sets are quite incompatible.
Turning to the eyepiece question, the Zeiss 160mm tube length objectives certainly needed compensating eyepieces (Zeiss eyepieces marked "K-Pl" are the best to look out for - but be warned they fetch quite high prices in good condition). I don't know enough about the infinity corrected Zeiss optics to know what they need, nor about Leitz. However, for non-critical visual observations, you should get away with using the wrong kind of oculars. The effect of using the "wrong" kind (i.e. compensating when the objective requires non-compensating, or vice-versa) is to show visible colour fringes (known as lateral chromatic aberration) around the bright/dark edges of the image.
You have several alternatives. Either buy a recent infinity scope (not that common or cheap on the second hand market, but findable; plenty of new scopes and accessories available but very expensive) to make use of the 3 modern objectives, and sell the others, or sell the 3 modern objectives and buy an older 160mm tube length Standard scope (extremely well made, quite good value and easy to find on the second hand market; no new accessories available but lots of second hand stuff ). Depends to some extent on what you want to do. Unless it's very urgent, I suggest you take some time to research and consider, as the decision you make will lock you in to a particular path indefinitely.
Hope this helps, and I'm sure someone else can fill in the gaps.
David -- David Littlewood .
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