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Sight Tube For f4 Dobsonian

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#1 briansalomon1

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Posted 05 December 2021 - 09:11 PM

I need a sight tube for my f4 Dobsonian. I've only had this scope for a few weeks and just recently collimated it pretty close to correct (better views of Jupiter than I get with NP101) but have the wrong size sight tube for my scope and need the 2" model.

 

I like the Astro Systems Light Pipe Sight Tube/Cheshire Combination Tool but can't seem to find it anywhere except eyepiecesetcetera.com.  The problem is his site simply refuses to allow me to complete a purchase so I have to call him and it clearly puts him out. It's simpler if I buy somewhere else.

 

Does anyone know who else carries the 2" f4 version?

 

What are you guys using for a sight tube?

 

 



#2 Vic Menard

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Posted 05 December 2021 - 09:33 PM

The short 2-inch AstroSystems LightPipe has an EFL of 3.4 (about the same EFL as the fully retracted Catseye TeleCat XL). The fully retracted Catseye TeleCat XLS (short version) has an EFL of 2.9. I have an f/4 StarStructure and I use the TeleCat XLS almost fully retracted to discern the three alignment circles with discrete, incremental steps between each circle. I find the fully retracted TeleCat XL to be a bit too long for my f/4 Dob, but I'm not sure that your scope's parameters will be the same as mine. That said, I routinely recommend the XLS for f/4 scopes--it seems to get the job done.

 

If your mind's made up and you still want the AstroSystems LightPipe, and you can't get Don's site to work for you, have you tried going to the source?  https://www.astrosys...iz/coltlsm1.htm


Edited by Vic Menard, 06 December 2021 - 12:56 PM.

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#3 GDAstrola

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Posted 05 December 2021 - 09:37 PM

Don at eyepiecesetc.com was great to work with and I bought two Light Pipe sight tubes from him.  Give him another try.



#4 briansalomon1

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Posted 05 December 2021 - 10:04 PM

Don at eyepiecesetc.com was great to work with and I bought two Light Pipe sight tubes from him.  Give him another try.

I agree, Don is a great guy, and no one else seems to have the issue. It's just that I'm a very thorough type of person and am 99.9% certain the issue not on my end.

 

I gave a solid effort and can't solve the problem on the other end, but am certain I can solve the problem of finding a sight tube that will work.



#5 EJN

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Posted 05 December 2021 - 10:26 PM

I need a sight tube for my f4 Dobsonian. I've only had this scope for a few weeks and just recently collimated it pretty close to correct (better views of Jupiter than I get with NP101) but have the wrong size sight tube for my scope and need the 2" model.

 

I like the Astro Systems Light Pipe Sight Tube/Cheshire Combination Tool but can't seem to find it anywhere except eyepiecesetcetera.com.  The problem is his site simply refuses to allow me to complete a purchase so I have to call him and it clearly puts him out. It's simpler if I buy somewhere else.

 

Does anyone know who else carries the 2" f4 version?

 

What are you guys using for a sight tube?

 

If you have a 1.25" sight tube, just put it in a 2" to 1.25" adapter and it should work fine. That's what I do.


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#6 briansalomon1

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Posted 06 December 2021 - 07:27 AM

If you have a 1.25" sight tube, just put it in a 2" to 1.25" adapter and it should work fine. That's what I do.

That's what I've done and It works fine for centering the secondary but even when I have it completely retracted I can't see the actual edges of my primary mirror. I checked the link Vic provided and sure enough, they have the 2" f4 model.




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