Upgrading oculars

75RR · Post by **75RR** » Mon Jun 09, 2014 7:25 pm

Can I upgrade my 12,5 Zeiss/Winkel from a Zeiss Junior Standard KF to a KPL-W 12,5/20 without problems? Have tried them and they are brighter and have a larger field of view but seem to have a thin redish/yellowy ring on the outer edge. There also seems to be a smudge at 5 o'clock.
Main thing is I am having trouble looking through them, just a small movement of the head and I lose sight down the tube.
Also wondered if one can combine two models of ocular as shown in the photo.

Pau · Post by **Pau** » Tue Jun 10, 2014 12:42 am

The orangeish halo is normal: this is because it's a compensating eyepiece, needed to give the best correction with Zeiss objectives. May be not adequate for very old low power objectives, but KPL are the best for most classic 160 corrected Zeiss objectives from the Standard/Universal series.
The smudge is not normal, of course. Check if there is dirt, delamination or any other optical issues
You can combine the eyepieces, but to avoid visual issues use the same magnification FN and eyepoint at both eyes .

75RR · Post by **75RR** » Tue Jun 10, 2014 5:25 am

Thanks for the reply Pau.
Have calmed down, ignored orangeish halo, spotted and dealt with smudge and
realized that the viewing problem was as simple as adjusting seat height, to compensate for oculars that protrude a little more.
I like simple solutions, even if they do make one look silly!

Ichthyophthirius · Post by **Ichthyophthirius** » Wed Jun 11, 2014 3:46 am

Hi, The two eyepieces on the right, "Kpl W 12,5x/20 Br" and "Kpl-W 12,5/20 Br" are optically equivalent. They have a parfocal length of 10mm (DIN) and can be used together on every 160mm stand with the regular Zeiss finite objectives (time period 1945-1990s; intermediate image distance 150mm).

The Zeiss-Winkel eyepiece is different. Zeiss-Winkel eyepieces have a parfocal distance of 5mm. They work with Zeiss-Winkel objectives* (time period until 1957) that have the corresponding intermediate image distance of 155mm (+5mm compared to DIN).

A 5mm difference can lead to loss of parfocality (low magnification) and impair image quality (high aperture objectives).

What objectives do you have (if you post an image we might be able to help you with identification)? If you have Zeiss-Objectives, you won't have any problems. If you have Zeiss-Winkel objectives, the first thing you can try is to raise the eyepieces by 5mm using a little tubes made from paper or cardboard.

Regards, Ichthy

*The situation is even more complicated when it comes to different Zeiss-Winkel objectives. Therefore, let us know what objectives you're actually using. http://www.mikroskopie-forum.de/index.php?;topic=1698.0

75RR · Post by **75RR** » Wed Jun 11, 2014 5:48 am

*The situation is even more complicated when it comes to different Zeiss-Winkel objectives. Therefore, let us know what objectives you're actually using. http://www.mikroskopie-forum.de/index.php?;topic=1698.0

Thanks Ichthy,
Had a look with google translate, think I got the gist of it. Very interesting.
The microscope came with the 3 objectives on the left. Unfortunately in both the 40x and the 100x the spring is stuck (old grease?). Have not therefor tried the 100x. The 40x can be focused, though I find the image rather dark.(That might well be the fault of my unorthodox lighting arrangement)
Originally picked up the 2.5x to be able to see the forest and then choose a tree, the 16x I got at a reasonable price while looking for a 20x or 25x which I have still not found.

glen

Ichthyophthirius · Post by **Ichthyophthirius** » Wed Jun 11, 2014 9:11 am

Hi Glen,

The two objectives on the right, Plan 2,5/0,08 and Plan 16/0,35 are fully compatible with the Kpl W 12,5x/20 (both of them) at 160mm tube length.

The three objectives on the left are Zeiss-Winkel achromats. I don't have these myself, but it is very likely that these will have an intermediate image distance of 155mm. Therefore, to use the 40x and 100x objectives with the newer Zeiss eyepieces Kpl W 12,5x/20 in the best arrangement, you have to extend the tube by 5mm to 165mm.

I don't know how well the Kpl W 12,5x/20 eyepieces compensate the CVD of the Zeiss-Winkel objectives.

If you want to mix the objectives, go for 165mm tube length. Parfocality of the low magnifications will be lost, but image quality won't be affected.

Ichthy

P.S.: It is possible that the 100x objective might not have a spring mechanism?! The spring mechanism was invented around that time - so this might be one without.

75RR · Post by **75RR** » Wed Jun 11, 2014 9:36 am

Hi Ichthy,
thanks for the 165mm tip.
Would like to use the 10x and 40x so will work on a home made solution.

P.S.: It is possible that the 100x objective might not have a spring mechanism?! The spring mechanism was invented around that time - so this might be one without.

Posting some photos to see if this can be seen.

thanks
glen

Pau · Post by **Pau** » Wed Jun 11, 2014 9:49 am

They seem spring loaded: I can see both the movable noses in the left image and the springs themselves inside the objectives in the right one. But just press the objective tip (without touching the lens) to test if it works OK.
The front lenses seem dirty (although maybe the image glare), a good clean could be convenient.

Ichthy, interesting info about Zeiss-Winkel, I had no idea about it.

75RR · Post by **75RR** » Wed Jun 11, 2014 10:12 am

But just press the objective tip (without touching the lens) to test if it works OK.

Tried to loosen them the other day by warming them on my monitor(old fashioned one) no luck.
Stuck solid.

Will clean lens again! Though I think that is the effect of lightening the image in photoshop.

glen