obtaining and installing reticle in oculars

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brettpim
Posts: 75
Joined: Thu Mar 26, 2015 7:09 pm

obtaining and installing reticle in oculars

Post by brettpim »

I have a Reichert Zetopan with 10x BPK oculars. My friend has a Zeiss Universal III with CPL W10x/18 "eyeglass" #46 40 23-9901 oculars. We both want to insert eyepiece reticles and are looking for advice on determining the diameter we need and instructions to install. We have some manufacture specific questions:

The Reichert BPK oculars are Kellner type but the bottom cylinder does not unscrew. From the bottom there does seem to be a small ridge which might be the spot for a reticle, but I am not sure. If not, I would have to go through the top (removing the lenses) and then there is a shoulder inside the tube and also, further down, a little ridge. How do I determine which of these spots is for a reticle? Does anyone have direct experience inserting a reticle in a Reichert 10x BPK ocular from the Zetopan?

For the Zeiss, I looked at this list of reticle diameters. Is the "Kpl-W 10x/18 [#46 40 43-9902]" from the list similar enough to ours to be the right one? What are the differences between 23/43 and 9901/9902? The bottom of the Zeiss ocular screws off and there is a ridge with a retaining ring already there. If someone has direct experience installing a reticle in this ocular, can they confirm this is the spot to install the reticle?

Does anyone have advice on where to buy reticles?

brettpim
Posts: 75
Joined: Thu Mar 26, 2015 7:09 pm

Post by brettpim »

With calipers and by scratching a "1" on a disk cut from clear plastic packaging, we were able to determine the following:

For a Reichert 10x BPK ocular the reticle diameter is 21mm. It is installed by unscrewing the top of the reticle and removing the lenses. There is a small shoulder that the reticle will rest on about 1-2 cm up from the bottom edge of the ocular. From the plastic disc experiment it seems that the the bottom of the reticle disk is in focus.

For the Zeiss Kpl-W 10x/18 [#46 40 43-9902] ocular the reticle diameter is also 21mm. It is installed by unscrewing the bottom of the ocular and installing the reticle from the top of the unscrewed tube.

I ordered reticles on ebay. When I installed it in the Reichert BPK, it is not quite in focus. If anyone has a suggestion of another place to buy reticles which might work better, please let me know.

I made a spring retaining ring from a safety-pin which is hard to install without touching the reticle disc and is slightly too tense. Does anyone have suggestions for making a better retaining ring?

Ichthyophthirius
Posts: 1152
Joined: Thu Mar 07, 2013 5:24 am

Post by Ichthyophthirius »

Hi,

The little rest you saw in the eyepieces (and that will be present in all/almost all eyepieces) is the field stop of the eyepiece. That is the optically correct location for a reticle. However, it is not necessarily a location intended by the manufacturer.

You are never meant to remove lenses from an eyepiece. If it is difficult, you're in the wrong place! You only ever remove either the bottom of the eyepiece or an insert screwed/pushed into the base of the eyepiece.

Some companies intended for recticles only to be inserted into focussing eyepieces (the ones with a diopter scale). The scale on the reticle is then brought into focus with the diopter. Glass has a higher refractive index than air; so after inserting a reticle the image will be slightly out of focus if you don't have a diopter.

The Zeiss "46 40 23-9901" is a focussing eyepiece, so what you did there was intended by the manufacturer.

I suspect that the Reichert 10x BPK isn't a focussing eyepiece that's why it wasn't easy to insert a reticle. The reticle is also slightly out of focus; buying a new one won't help. You could still try to turn it around by 180 degrees so the markings might get closer to the intermediate image.

Regards, Ichty


I can't find any instructions for Reichert. Here are just some other instructions for general interest.

American Optical https://user.xmission.com/~psneeley/Per ... icle-1.JPG

Zeiss Standard 25
Image

Olympus CX41
Image
Last edited by Ichthyophthirius on Sat Feb 01, 2020 4:53 pm, edited 1 time in total.

Ichthyophthirius
Posts: 1152
Joined: Thu Mar 07, 2013 5:24 am

Post by Ichthyophthirius »

I had a look at the Zetopan instructions http://www.science-info.net/docs/reichert/zetopan2.pdf It just says insert measuring eyepiece.

I presume that means Reichert sold measuring eyepieces only and that the other eyepieces were not meant to be retrofitted with reticles. See examples below with "adjustable eyelenses". http://www.science-info.net/docs/reiche ... ts-4MB.pdf

You might have to find a measuring eyepiece (they might be marked "m") or use a pair from another company.

Image

brettpim
Posts: 75
Joined: Thu Mar 26, 2015 7:09 pm

Re: obtaining and installing reticle in oculars

Post by brettpim »

I was putting together a Leitz Ortholux for a friend and I noticed that they had two oculars were identical and one had a reticle which caused no focusing problems compared to other without a reticle. The oculars were a simple design with one lens at top and one at bottom. I think this is the Huygens design. Is it the fact that the focal plane is between the two lenses which allows these to take a reticle without having a focusing mechanism built-in?

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