WTB/ barrow 30mm Centering telescope lens

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fjordwarrden
Posts: 16
Joined: Mon Mar 28, 2022 5:55 pm
Location: United States, Santa Cruz California

WTB/ barrow 30mm Centering telescope lens

#1 Post by fjordwarrden » Wed May 04, 2022 8:50 pm

So I was super fortunate and acquired a Zeiss AxioSkop-20 with phase contrast that fit my tiny, much depleted student budget. The kindness of strangers seems to know no bounds! I would like to insure my phase annuli are properly aligned and need a 30mm CT. I am in Santa Cruz California. If anyone wants to sell-one or is local and would let me barrow it briefly, I would be much appreciative.

abednego1995
Posts: 137
Joined: Thu Dec 15, 2016 6:32 am

Re: WTB/ barrow 30mm Centering telescope lens

#2 Post by abednego1995 » Fri May 06, 2022 7:24 am

One way to do it without a centering telescope, is to remove one eyepiece and look down the tube. You'll see the phase annulus of the condenser and the phase plate of the objective.
Another quick way is to use a 10x loupe to magnify the aerial image of the annulus and phase plate above the eyepoint of your eyepiece.

Cheers,
John

apochronaut
Posts: 6270
Joined: Fri May 15, 2015 12:15 am

Re: WTB/ barrow 30mm Centering telescope lens

#3 Post by apochronaut » Fri May 06, 2022 2:05 pm

Another way is to stack the eyepieces one on top of the other. You can use a piece of tape or some tack to hold the top one.Modern eyepieces that I have tried this with work but many of the older ones, like Huygens don't..

fjordwarrden
Posts: 16
Joined: Mon Mar 28, 2022 5:55 pm
Location: United States, Santa Cruz California

Re: WTB/ barrow 30mm Centering telescope lens

#4 Post by fjordwarrden » Tue May 10, 2022 2:53 pm

Thanks, I have heard of this technique but I hadn't tried it yet.

fjordwarrden
Posts: 16
Joined: Mon Mar 28, 2022 5:55 pm
Location: United States, Santa Cruz California

Re: WTB/ barrow 30mm Centering telescope lens

#5 Post by fjordwarrden » Thu May 19, 2022 2:16 am

Tried it out and could see how it would work. I would need to find the right size tube so I could hold the two lenses the right distance apart and in place.
Still if anyone has a CT I'm still considering buying one as a option.

Greg Howald
Posts: 1185
Joined: Tue Oct 20, 2020 6:44 am

Re: WTB/ barrow 30mm Centering telescope lens

#6 Post by Greg Howald » Thu May 19, 2022 2:39 am

I made a sliding tube for this using an empty paper towel role and a good amount of scotcth tape. I admit it wasnt pretty but It actually worked quite well and was focusable.

Greg Howald
Posts: 1185
Joined: Tue Oct 20, 2020 6:44 am

Re: WTB/ barrow 30mm Centering telescope lens

#7 Post by Greg Howald » Thu May 19, 2022 2:41 am

Use a ten x, 23mm eyepiece inside the tube and expand it to put the 30x in the end of the outer sliding tube.

henry_j66
Posts: 3
Joined: Mon Jun 06, 2022 8:55 am

Re: WTB/ barrow 30mm Centering telescope lens

#8 Post by henry_j66 » Mon Jun 06, 2022 9:04 am

I got the 30mm centering telescope lens, let me know if you're still interested in it henry_j66 at aol dot com for a better conclusion,

Thanks.
James Henry

viktor j nilsson
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Joined: Thu Aug 23, 2018 10:12 pm
Location: Lund, Sweden

Re: WTB/ barrow 30mm Centering telescope lens

#9 Post by viktor j nilsson » Mon Jun 06, 2022 9:27 am

I'd be very sceptical of buying something like this from a new member with three comments, all trying to sell hard-to-find items.

Seems very unlikely that someone would have a spare Zeiss Axiomat 50x PlanApo, a 30mm phase telescope, and a Russian MBC-10 camera attachment...

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