MicrobeHunter.com Microscopy Forum

With phase objectives/condensers, it is recommended that one uses a phase eyepiece/telescope to center the optics.

What do you use?

Thanks

A centering/phase telescope. You can do a reasonable job without one, just by looking down the eyepiece tube, but the centering/phase telescope makes it much easier and much more accurate.

I thought they were important enough I bought three to go with three surplus Zeiss Standard 14 phase scopes I refurbished and donated to a high school just this evening.

If your eye sights are good, you can simply remove an eyepiece and squint into the empty tube. Centering telescope is not always needed. I can get phase contrast without CT, but CT is convenient and comfortable to use (such that I do not have to squint).

If your scope had a Bertrand-lens it would do the same job.

I bought a box of them from China , so the shipping was not too bad. It ended up being less than 5.00 added to the cost, which is well below the same item being sold on ebay. I have sold a few and everyone likes them so far. I still have them for sale if anyone wants one. They are the standard one supplied with Chinese phase microscopes with 23mm ocular tubes.
P.M. me.

I made one using two eyepieces. This might be helpful if you want to DIY:

viewtopic.php?f=12&t=17733&p=131935#p131935

Hi. Do you have any of the phase telescopes still available for sale please? If so how much?
Cheers
Frankiev

I use a Bertrand lens. And if necessary, visual correctiion while working on specimens.

Of note, make sure to check that the phase annulus in your condenser has clicked correctly into place before recentering. I made that mistake alot when starting phase contrast. When all it takes is a slight push back and forth on the selector in the condenser, it is plain stupid to switch in the Bertrand lens/phase telescope, and dealign your objectives in trying to fix something that isn’t broken.

Frankiev wrote: ↑

Thu Dec 21, 2023 1:44 pm

Hi. Do you have any of the phase telescopes still available for sale please? If so how much?
Cheers
Frankiev

P.M. me.

I've tried to pm you Apochronaut but don't know how successful I've been. My skills in these things are very limited

Thank you all for the your help and advice. A fellow microscopist is sending one to try.

Further to my last post and, having received the phase telescope which is intended for an Olympus
microscope , I find that it does not work for my Leitz.
Is it the case that they are always specific to a particular microscope?
I know that I can return this one so the request stands. Does anyone have a suitable telescope for sale please?

A phase telescope is just a magnifier that is capable of focusing on the back focal plane of the objective. Any one should work on any microscope, as long as there is enough latitude in the focus mechanism. The Olympus has a worm screw focus, does it not?
The generic ones with a push pull focus adjustment may have a greater latitude.
As mentioned, I have those and can try one out on a Leitz 170mm objective for you.

Yes the Olympus has a worm screw for focusing and I thought, as you say, that maybe there's not enough latitude in the movement. I did try lifting it slowly out of the tube as I continued to look through it but no joy.
I'd be very grateful if you could try on the 170 objectives.
If successful I'd be happy to buy one from you....how much are they?

Frankiev wrote: ↑

Tue Dec 26, 2023 7:55 am

Yes the Olympus has a worm screw for focusing and I thought, as you say, that maybe there's not enough latitude in the movement. I did try lifting it slowly out of the tube as I continued to look through it but no joy.
I'd be very grateful if you could try on the 170 objectives.
If successful I'd be happy to buy one from you....how much are they?

I think in $ but around £ 40. It is very light so shipping would not be too great, maybe about £12 or so.

I still have some 170mm objectives here and an older stand with a drawtube to adjust the tube length to 170, which would be the critical issue. That extra 10mm would make a big difference. These centering telescopes focus by drawtube with a thumbscrew lock, so they have quite a bit of latitude in the focusing system.

You might look on Amazon and see. Sometimes you can get free shipping although I rarely use it and hate it with a passion but I was able to get 4 coils for my van for 36.00 and free shipping, when the local parts supplier wanted 70.00 each.
The last time I looked on ebay, the same CTs were around $75.00. It seems that the unbranded ones around are all the same.

Thanks apochronaut for your help. As I am in regular communications with the guy who sold me the telescope I decided, in the first instance to get back to him, judging that it could well be my inexperience that was the problem. And indeed it was therefore, for the moment I shall stick with the one I have.
Thanks again
Frank