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1.25" spacer/washer similar to parfocal rings

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#1 DeWynter

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Posted 05 April 2021 - 06:09 PM

I recently put 1.25"-2" adapter to a few my eyepieces to convert them from 1.25" to 2". The biggest problem is that the bottom of the 1.25" eyepiece is exactly as the bottom of the adapter so if I put 2" filter then the bottom of the eyepiece will touch the glass of the filter and scratch it.

 

Has anyone seen some kind of 1.25" spacer or washer, similar to parfocal rings, but thinner. Like 1 - 1.5mm thick. Just want to put it between the eyepiece and the adapter. In the worst case I'll use parfocal rings, but if there is something much thinner I'll rather use it than parfocal rings.



#2 SeattleScott

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Posted 05 April 2021 - 06:16 PM

Well the problem is if it is that thin, how is it going to hold a screw to use with an Allen wrench to hold the ring onto an eyepiece? Do you plan on just glueing it to the eyepiece?

I guess in your case you have a screw on the adapter that secures the adapter, and hence the theoretical ring to the eyepiece. So that solves that. But yeah I doubt you will find anything for this specific application. Maybe you could slide the adapter out a little bit before securing it? Maybe have a rubber band or something elastic in the gap just to be safe?

Scott

Edited by SeattleScott, 05 April 2021 - 06:20 PM.

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#3 Couder

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Posted 05 April 2021 - 06:22 PM

Try nylon O-rings


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#4 NC Startrekker

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Posted 05 April 2021 - 07:45 PM

Another option is to extend the length of the skirt (barrel) on the 2” adapter using a 2” extension tube. They come in various lengths. 


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#5 rowdy388

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Posted 05 April 2021 - 07:57 PM

Elastic O rings from a hardware store will work fine. You can use more than one if necessary.

 

I use parfocal rings, o rings and a few extenders to make all my eyepieces parfocal so that I don't have to adjust the settings on my Paracorr ll.


Edited by rowdy388, 05 April 2021 - 08:02 PM.

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#6 cimar

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Posted 05 April 2021 - 09:58 PM

Hi,

I extended the length of my standard 2"-1.25"-adapter with a 14mm Baader Hyperion fine-tuning ring (Baader # 2958214). This solved exactly the problem you described.

After upgrading the focuser to a MoonLIte CR2, I don't need this anymore, because the moonlite 2"-1.25"-adapter is longer than the former standard one. I have multiple adapters which I install different filters to. So I can easily switch filters by switching the adapters and do not need a filter wheel.


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#7 CeleNoptic

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Posted 05 April 2021 - 10:18 PM


Another option is to extend the length of the skirt (barrel) on the 2” adapter using a 2” extension tube. They come in various lengths. 

 

That's exactly  what I use in my Dob 1.25"/2" focuser adapter, just small extension ring before filter... like this.


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#8 DeWynter

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Posted 05 April 2021 - 10:43 PM

Well the problem is if it is that thin, how is it going to hold a screw to use with an Allen wrench to hold the ring onto an eyepiece? Do you plan on just glueing it to the eyepiece?

It doesn't need any screw. It will be simply sitting between the eyepiece and the adapter not allowing the eyepiece to go fully inside. I simply need 1mm extra. So a 1mm washer with 1.25" diameter will do the trick. 

 

Another option is to extend the length of the skirt (barrel) on the 2” adapter using a 2” extension tube. They come in various lengths. 

Yes, I was thinking about that as well. It will be probably even more secure as well. I started googling for them, but got heaps of irrelevant links.

 

I extended the length of my standard 2"-1.25"-adapter with a 14mm Baader Hyperion fine-tuning ring (Baader # 2958214). This solved exactly the problem you described.

After upgrading the focuser to a MoonLIte CR2, I don't need this anymore, because the moonlite 2"-1.25"-adapter is longer than the former standard one. I have multiple adapters which I install different filters to. So I can easily switch filters by switching the adapters and do not need a filter wheel.

Brilliant! Thanks a lot! Why I didn't think about Baader Hyperion fine-tuning ring as well?!?! I knew about them before...



#9 MarMax

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Posted 05 April 2021 - 11:35 PM

When I need to make a 1.25" spacer I use plastic tubing from McMaster-Carr. There are several types of tubing with a 1.25" ID and a 1/8" thickness seems to be about right. Cost is about $10 for a one foot piece. I just cut them to the desired thickness with a band saw.


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#10 NC Startrekker

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Posted 06 April 2021 - 03:18 PM

That's exactly  what I use in my Dob 1.25"/2" focuser adapter, just small extension ring before filter... like this.

Exactly.  waytogo.gif 



#11 Miranda2525

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Posted 06 April 2021 - 06:50 PM

I recently put 1.25"-2" adapter to a few my eyepieces to convert them from 1.25" to 2". The biggest problem is that the bottom of the 1.25" eyepiece is exactly as the bottom of the adapter so if I put 2" filter then the bottom of the eyepiece will touch the glass of the filter and scratch it.

 

Has anyone seen some kind of 1.25" spacer or washer, similar to parfocal rings, but thinner. Like 1 - 1.5mm thick. Just want to put it between the eyepiece and the adapter. In the worst case I'll use parfocal rings, but if there is something much thinner I'll rather use it than parfocal rings.

Use small elastic bands. I use them in between adapters and the eyepiece and it works.


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#12 DeWynter

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Posted 06 April 2021 - 07:14 PM

Actually, yes, elastic bands would work as well. Thanks!


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#13 MarMax

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Posted 08 April 2021 - 10:12 PM

I came up with another spacer. I bought some for another purpose but they will work as 1.25" eyepiece spacers. They are only about 0.032" thick but you can stack them. I stacked six and the stack was 5mm thick.

 

Electrical-Insulating Hard Fiber Washer


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#14 bmcclana

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Posted 09 April 2021 - 08:51 AM

If anyone has a 3D printer it is easy to make a spacer to exactly the thickness you want.

I did this to parfocalize all my Morpheus eyepieces with a 30UFF for use in a coma corrector.

I used TPU flexible filament with a friction fit so they go on relatively easy, but stay in place once there. I put a picture in another thread here on CN.

#15 DeWynter

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Posted 09 April 2021 - 08:52 PM

I ended up buying a silicone washer from a local plumbing store. They are 1mm think, firm enough and have inner diameter exactly as the outer diameter of the 1.25" eyepiece barrel. Perfect!




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