Leitz dry objective for high magnification

[tonikon]

Hi everyone,
I'd like to use on my old Leitz microscope (black enamel series, 170mm tube length) a dry objective with magnification greater than the 40x Apo 0.95 that I already use with satisfaction (almost inexistent working distance apart...).
I'm thinking about two possible solutions:
- Leitz Apo 63x 0.95
- Leitz Fl 70 0.90
Both of them are old series 37mm parfocalized.
Could any of you give me advice on which one to prefer? The apochromatic objective is quite rare and it is generally very expensive. The Fl 70 objective has a slightly lower N.A: but perhaps it can be found at a slightly lower price.
Moreover, are there objectives of other brands that are fairly compatible with my scope? (Periplan correction, 37mm parfocalized, 170mm tube lenght..)
Thanks in advance for your advice.
Toni

[viktor j nilsson]

To be honest, most such objectives are quite disappointing and difficult to use compared to oil immersion objectives. I use my Nikon CF planapo 60x 0.90 mostly for quick checks of mushroom spores, etc, when I don't want to mess with oil. For photography, a 40x, 60x or 100x oil objective will provide a much, much MUCH better image, and be much easier to use (except for the cleaning up part).

[tonikon]

Hi Viktor,
I have to admit that the idea of ​​frequently cleaning delicate and expensive objectives is a bit troubling.
But above all, when I explore the content of a drop of water I often have to alternate frequently different magnifications and so it seems to me more convenient to have a fuul set of "dry" objectives, even if I imagine that the quality and usability are far inferior to the "oil" solution...

[BramHuntingNematodes]

You could a middle power immersion lens to complement the high power

[tonikon]

Thank you very much BMN,
I will try to follow your advice. In the old Leitz catalog there are many "oil" lenses, even of medium power ...
Ther is also some Water objective (W engraved)...they are said to be easier to use, but equally good even if water has smaller refractive index than oil...and perhaps you don't need to oil the condenser...

[mrsonchus]

Thank you very much BMN,
I will try to follow your advice. In the old Leitz catalog there are many "oil" lenses, even of medium power ...
Ther is also some Water objective (W engraved)...they are said to be easier to use, but equally good even if water has smaller refractive index than oil...and perhaps you don't need to oil the condenser...

This I have experience of. I had a beautiful Leitz Orthoplan before I switched to an Olympus BX50. I was lucky enough to find, simply by constantly checking the listings, both a 50X and a 100X water (as said, marked with a 'W') immersion objective of 1.00n.a.. They were quite simply superb both in quality and of course ease of use. These if you are able to find them, will definitely perform as well as the much more time-consuming oil-immersion objectives. I also had a planapochromatic 100X 1.32n.a. oil-immersion objective which was outstanding, and a 54X I think it was, also oil-immersion (I forget the n.a.), which was very good but I considered to be slightly inferior (slightly - only slightly) to the 50X WI objective. They were all for 170mm TL as per the Orthoplan of course.

Here are a few images of those beauties....



An image from the 50X above,

[MicroBob]

Hi Toni,
I have a Zeiss Jena 40:1 0.95 Apo obective with cover slip correction collar and use it a lot. It has a tiny free working distance so only usable for pond samples when the slide is properly assembled with a thin water layer. So generally these high power dry objectives are very useful, but only if one is prepared to work carefully. With my Zeiss Phomi 1 and it's Optovar I can use the increaded resolution very well.
On the other hand side oil immersion is no big problem: Just wipe the objective with a piece of tissue. Halfway modern immersion oils don't gum up quickly. Cleaning the slide is messy and time consuming though. When I use oil immersion, I take care that I use a nosepiece with at least a 40:1 or 50:1 objective next to the 100:1 to have a medium high magnification available. I also have a good 22:1 oil objective so this is avery comfortable setup too.

When do I use what? For a quick look, scanning through slides or a quick forum photo of a new project I use the dry objectives. When I wan't do make optimal images and spend more time on a slide I use oil.

When choosing between your two objectives I would make shure it has a correction collar. After that it also depends on whether you use a microcope with magnification changer like the Optovar.

Bob

[tonikon]

Thank you very much Mrsonchus for your very helpful and very detailed reply! The "Water immersion", in terms of time and "feasibility", in a very good compromise. Unfortunately, I'm not able to view your images, but I'm beginning to hunt the two W Leitz (especially the W50 1.00)
Thansk again.
Toni

[tonikon]

Hi Bob,
I think your Zeiss Jena 40 0.95 Apo is a "twin" of my Leitz Apo 40 0.95 (with similar correction collar) ... I also have the same problem as you: a tad greater thickness of water or a less thin coverslip is enough because the lens is not usable, since its end "touches" the coverslip, with disastrous consequences ... probably, by setting the maximum thickness value of the coverslip (if I remember correctly, 0.22), you can recover a few microns of w.d. and work a little better, but I don't know what impact in terms of image quality.
I have always considered oil immersion as a "complication", because I am a true newbie and I have no experience. But now I'm understanding that immersion (in water or in oil) is essential to exceed 20x-30x with good results. Now, I have to redo my projects and "familiarize" with the "immersion techniques"...

[BramHuntingNematodes]

But now I'm understanding that immersion (in water or in oil) is essential to exceed 20x-30x with good results. Now, I have to redo my projects and "familiarize" with the "immersion techniques"...

I wouldn't say essential in all cases, just easier.

[tonikon]

One thing is for sure: the best thing when starting a new adventure (like microscopy) is to understand that there is really a lot to learn ... and everything is easier when you find a forum like this, full of people collaborative and knowledgeable who helps so much newbies like me!

[mrsonchus]

Thank you very much Mrsonchus for your very helpful and very detailed reply! The "Water immersion", in terms of time and "feasibility", in a very good compromise. Unfortunately, I'm not able to view your images, but I'm beginning to hunt the two W Leitz (especially the W50 1.00)
Thansk again.
Toni

Try it now - apologies for the earlier mess-up!

[tonikon]

Try it now - apologies for the earlier mess-up!

Now is perfect! Two real gems and a wonderful image...

[mrsonchus]

They really were superb.
You need to ensure that your TL is correct for your 'scope - there are 160mm and 170mm (Ala Orthoplan in the above case) 'scopes and objectives.

[MicroBob]

Leitz 45mm objectives with 160 and 170mm tube length an be mixed as the 160mm were used with eyepieces with intermediate image 10mm down the tube, 170mm with eyepieces with intermediate image 18mm down the tube, in effect not much difference. I posted a link to a comarative table somewhen.

Bob

[mrsonchus]

Here's a link to an explanatory (internal) Leitz memo at the time of Leitz adoption of the std 160mm TL....

[tonikon]

So, can I use also the much more recent 160mm objectives (like the EF series) in conjunction with my old 170 microscope? Only the problem of parfocality would remain ...This looks very very interesting...it open the doors to a lot of new possibility and jeopardises my already damaget wallet!

[apochronaut]

Bear in mind that older apochromats require compensating eyepieces and that usually entails a restricted f.o.v., especially if you opt for 10X eyepieces. Depending on the era of manufacture it can be as low as 13 or 14mm.
We are used to seeing a continuous stream of W.F.10X eyepieces these days being used as a default. That is only really neccessary with conventional moderate N.A. objectives. It was more common with the older extensive lines of apochromats to use a 15X eyepiece as a default. A perusal of older catalogues or if possible a hands on experience will show the compensating 15X eyepieces to provide a wider f.o.v. and greater eye relief than the equivalent 10X. The 4mm .95 objective with a correction collar was a universally made objective. Just about every manufacturer made one and it was mostly used as a 600 to 700X objective, depending on the original magnification. This was the rationale for the older high magnification apochromats , having a magnification of 90X rather than 100. 90 X 15 = 135, or about the maximum a 1.3 N.A. objective could sustain. The 3mm or 60X were usually offered as a dry .95 or oil 1.4 giving the option for using a 15X or 20X eyepiece to maximize the resolution.

I would think your 37mm parfocal Leitz objectives would fall into this category. Eyepieces and wider fields began to be more universal by sometime into the 50's.
Unfortunately the attraction of high power eyepieces persists to this day, and outside of 12.5 or 15X has become a useless feature associated with entry level kits.

[Rossf]

Hey mrsonchus I concur on the 50 and 100x W objectives-got them and the 25x W version also-the 100x seems low N/a but sharp enough for the convenience-I notice some are flouresenze and others are not-is there a difference between flouresenze and non flouresenze versions optically? They all respond well to oblique lighting and trick out into pseudo phase nicely but the 100x in particular is flouresenze and gets a really nice light blue background when using oblique lighting-I may hunt down the planachromatic 1.32 oil you speak of-if I’m mucking about with oil I want it to be outstanding for the effort!-I’ve seen plenty of planapo 100x on eBay and noticed a couple had a larger than usual front element-is this the one you speak of? I’ve a few amazing observations with a bog standard 1.25 where when a slide prep is winding down and the ciliates are just pretty stationary (and fill up the entire field!) but still beating their cilia and other organs functioning and there seemed to be swarming tiny bacteria in parts of its anatomy or something else but resolving power just wasn’t quite good enough to really make out-does the extra 1.32 resolve considerably more detail?
Regards Ross

[mrsonchus]

Hi Rossf - here's one of the 100X listed now in the U.K.. The seller is one from whom I've bought several times and is totally honest and reliable in my experience. Very likely responsive to an offer too. I've no connection whatsoever with this seller beyond my custom of course.

[MicroBob]

This objective is fairly often delaminated - I have two, one delaminated, one with loose front lens. So I would specificslly ask for this to be checked.

[mrsonchus]

I didn't have that problem but it's definitely worth checking. Rest-assured though that the seller listing is honest and would I'm sure refund you if you had any problems. The 100X apo that I had was a really bright & clear objective, a real performer. There's no harm in asking for a final check - always good advice.

[MicroBob]

I have once bought two heavily delaminated Zeiss objectives from a microscopy professional, a real expert. The delamination problem hadn't crossed his way before, so he didn't check the objectives with a phase telecope or Bertrand lens. He was absolutely honest and I got my money back but this shows that it is easy to miss such a problem. The objective with the loose front lens also passes inspection by a real expert, this just happens.

[Rossf]

Hey mrsonchus I ended up grabbing the 100x plan apo-got about $100 bucks off asking price-I remembered I’ve bought from that seller before without problems-just curious-got a black laborlux late 60’s and heine condenser and dark field condenser but yet to get a bright field condenser! I haven’t had it long-my excuse anyway-did you use the 600 boat shaped flip top ones to get the best out of the Apos and if so what screw on head did you use? The simpler As,the Achro or the achro/aplamat 1.4? Or did you use the Berek? I can’t make my mind up-I’ve heard the Berek gives best Koehler illumination but the 600 is more corrected for the apos-
Regards Ross
Thanks for the heads up on the listing.

[mrsonchus]

Hi Rossf, I used the 600 series condenser Apl 1.25 oil flip-top,


Remember that a supplementary lens 'K4' is optimal for the bottom of the condensers for the ultra-wide FOV of the Orthoplan in particular - other lenses (which simply push-fit into the condenser's base) such as the 'K1' optimise for other Leitz models also, see this snippet gleaned from internet when I had my Orthoplan....


If you search this forum for mrsonchus posts you'll find numerous posts of mine re my Orthoplan days and my hunt for parts and enhancements.....

[Rossf]

Thanks heaps for the info mrsonchus!
Regards Ross