Infinity objective

[RogelioMoreno]

On this thread I show a stacked image taken with a L Plan 20/0.4 infinity objective.

The L Plan 20/0.4 has RMS thread (when I bought it I was thinking it was a Nikon L Plan CFI60 serie with M25 thread and 60mm parfocal) and 45 mm parfocal with a WD of about 10mm. Few weeks ago I bought a old Vivitar 200mm M42 lens (inexpensive on eBay) with the idea of use it as a tube lens for a Nikon Plan 10/0.25 infinity objective that I have. I decided to use the Vivitar as tube lens of the L Plan 20/0.4, you can see the result on the thread that I mentioned above.

Here a picture of the camera + Vivitar 200mm and some M42 spacers (the camera in the picture is a old Canon 500 only for illustration because I was using my Canon 450D to take the pictures):


To use the camera + Vivitar lens on my Nikon Labophot I removed the trinocular head I mounted the camera + Vivitar lens on the Labophot stand.

Here a picture of how I plan to use the objective with a horizontal setup that I am building:


Rogelio

[AndrewC]

Myself, I would want a bit more support under the lens on the horizontal setup.

Andrew

[RogelioMoreno]

Andrew,

Good point!

Rogelio

[g4lab]

Rogelio, I think you have opened up a whole new vista for people doing this.
There seem to be lots of infinity lenses out there.

If I am forgetting anyone who did this earlier, please correct me.

Very interesting, and exciting.

Gene

[rjlittlefield]

If I am forgetting anyone who did this earlier, please correct me.

I do not recall anyone showing pictures before. Charles Krebs has mentioned trying this, with mixed results.

I will be interested to see how this concept develops. Previously we have had extensive discussion of which finite objectives work well for direct projection, no other optics. For infinity objectives, there is the additional complexity of which long lens, and possibly at what spacing. With good luck, most combinations will turn out to work well.

--Rik

[rjlittlefield]

For infinity objectives, there is the additional complexity of which long lens, and possibly at what spacing. With good luck, most combinations will turn out to work well.

When other people try this, I would like to see reports of failures as well as successes. If some combination vignettes, or gives color fringes, or gets soft on the edges, please show us that!

Otherwise I am afraid we may run into the "media bias" problem that I talked about with lens combos, where all the reported combinations work great but most of the possible combinations probably do not.

--Rik

[Charles Krebs]

Rik,

My mixed results were when an infinity objective was used directly with no tube lens. I do have a 5X Mitutoyo set up with a 210mm f9 Apo-Nikkor as the tube lens and the results are quite excellent. (I did post an image or two made with it somewhere here, but I did not mark them as such... and I hate to say it, but I can't remember what they were! )

The thing is, as has been discussed before, at 5X there are many good options for lenses, many of which are less cumbersome. But... this approach would be much more helpful at 10X and up, especially as the supply of infinity corrected "M" type objectives seems to grow regularly on eBay. (Just keep in mind that Zeiss and Leica still do some chromatic correction in the tube lenses. And the original Olympus "M" infinity microscopes still used corrective eyepieces.)

[ChrisR]

I haven't found any data on L Plan Nikon objectives. Anyone?

It would also be interesting to see if anyone has a Mitutoyo infinite lying about, to try, such as their 20x objective with 30.5mm WD.

Having an old-fashioned sensor I could use a longer tube lens, so I've ordered the plumbing to try a couple of infinites I have on a 400mm. If they fill the frame, I think I'll be astonished.

[Charles Krebs]

Chris,

For the newer Nikons of this type you need to check into their "industrial" microscopes. They tend to separate them from the "biologicals".
Try here:
http://www.nikon.com/products/instrumen ... /index.htm

and the "Specifications" tab here:
http://www.edmundoptics.com/onlinecatal ... uctid=2690

[rjlittlefield]

My mixed results were when an infinity objective was used directly with no tube lens.

Thanks for the clarification. I thought I remembered some issues with vignetting and coverage also, but I have not tried to relocate the postings and memory is always doubtful.

--Rik

[bklein]

So I'm a little curious in regards to the 200mm lens. I have a Nikon telephoto 200mm but since the Nikon scope accomplishes this with a much physically smaller lens I started looking. One place, surplusshed.com, has like 3 or 4. Would one of them work? Under $20.
Lots of cool stuff there btw.

Barry

[RogelioMoreno]

So I'm a little curious in regards to the 200mm lens. I have a Nikon telephoto 200mm but since the Nikon scope accomplishes this with a much physically smaller lens I started looking. One place, surplusshed.com, has like 3 or 4. Would one of them work? Under $20.
Lots of cool stuff there btw.

Barry

Barry,

First try with your Nikon 200mm telephoto, use a set of step-down rings until you get 42mm (for this I bought a 52mm to M42 step down ring), after that you can use M42 extension and a RMS to M42 adapter (if you have the RMS to T2 adapter then get a T2 to M42 adapter). To mount the Nikon CFI60 series objectives you would need a M25 to RMS adapter.

Rogelio

[Joaquim F.]

Hello, a very nice work Rogelio, I'm trying too some infinity corrected objectives mounted in front of a nikkor 200/4 AI, namely the Nikon CF Plan EPI oo/o as I could find on the web are mounted in industrial microscopes mid-90s.
They appear to be a first generation Nikon infinity corrected optics, as they have RMS screw and a parfocal distance of 45mm, new objectives have different specifications.
For the people interested in that optics I found some information on the components of that system here:

http://www.capraoptical.com/products/ni ... tives.html

In addition to information and diagrams of the objectives is possible view all components of the microscope following the links next to the drawing component: click on "revolving nosepiece", etc...

Unfortunately the information of the standard tube lens is not available ... and i´m not sure if the actual tube lens available in Edmundoptics is the same design as those of the 90´s Optiphot system.

Best regards

Joaquim

[Chris S.]

This is an interesting area to me, and Rogelio and I have corresponded a bit on it. Kudos to Rogelio for carrying out the experiments.

I'm not an optics guru like some other members of this forum, but in my ignorant mind, it seems to me that any "infininite" objective simply sends the light beams toward the eyepiece in a "collimated"--or "parallel" form. Any lens that decollimates--or bends parallel light beams such that they meet at a given point--should work as a tube lens and make infinitey-corrected objectives perfectly usable, so long as chromatic abberation is controlled elsewhere. And decollimating light is pretty much what standard camera lenses do. Of course, I'm just an ignorant macro photog, but so it seems to me--until one of you math/optics gurus sets me straight. And I already have a bunch of finite CF objectives, so the point is somewhat moot to me. But what Rogelio is doing makes sense to me, and could be a good answer for a lot of people.

Am waiting to hear those with much more knowledge than mine weigh in. Go ahead--I don't mind looking like a fool--it's my natural state.

Cheers,

--Chris S.

[rjlittlefield]

Chris, this should illustrate the issue.

What we're seeing here are central rays at the edges of the sensor. (The diagrams got too messy when I tried to show the whole cones.)



You can see that the telephoto used as a tube lens is forming peripheral parts of the image using portions of the lens that would normally be used only at very wide apertures.

The effect gets worse with greater separation between the objective and the telephoto. With too much separation, you'll get obvious vignetting. Less than that, and it's just that you won't be using the best parts of the glass. This is not a catastrophic problem, just some degradation of the edges.

The effect shown here can be reduced by using a shorter tube. Offhand I can't think what bad effect a shorter tube could have, but sometimes my imagination fails me.

--Rik