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Mewlon 210 with Moonlite Focuser / Binoviewer

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#1 ckwastro

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Posted 17 September 2019 - 02:32 PM

Hello,

 

I have a Mewlon 210 and would like to upgrade it with a Moonlite focuser. Does anyone have this upgrade who also uses a binoviewer? If so, do you have any issue bringing the scope to focus when using the BV?

 

I have a Denkmeier Power Switch that utilizes a 1.2x OCS that screws into the field end (before the diagonal) of the 2" AP MaxBright. I would think with the scope's moving-mirror focuser it wouldn't be too much of a problem to reach focus, but thought I'd check with the CN community first just to be sure.

 

Thanks for your time!



#2 Kunama

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Posted 17 September 2019 - 10:58 PM

Hello,

 

I have a Mewlon 210 and would like to upgrade it with a Moonlite focuser. Does anyone have this upgrade who also uses a binoviewer? If so, do you have any issue bringing the scope to focus when using the BV?

 

I have a Denkmeier Power Switch that utilizes a 1.2x OCS that screws into the field end (before the diagonal) of the 2" AP MaxBright. I would think with the scope's moving-mirror focuser it wouldn't be too much of a problem to reach focus, but thought I'd check with the CN community first just to be sure.

 

Thanks for your time!

I think you will struggle to get to focus with the Mewlon if you install a Moonlite or any other focuser to it.

Even with my Zeiss binoviewer and Zeiss T2 prism I have to use a short visual back to get focus without a corrector. If you add a Moonlite you will have use a OCS or GPC that gains at least 75mm.

That would also mean that you would be working at an effect FL of about 4800mm+.....

 

I suggest that instead you include a non-rotation T2 focuser into the parts train. That will allow you to fine focus after coarse focusing with the primary mirror....

The Mewlon 210 has about 160mm of back focus available from the 2" visual back.



#3 dr.who

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Posted 18 September 2019 - 12:00 AM

I can’t speak to the Moonlite but I use a Feathertouch focuser on mine and a Tele Vue binoviewer BUT I also use the 1.25x GPC and 1.25”  T2 system. The T2 system is mandatory. Without it you won’t come to focus. 



#4 ckwastro

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Posted 18 September 2019 - 08:41 AM

Thanks to both of you, appreciate the info. I’ll look at these options and see which will work better for me. 



#5 ckwastro

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Posted 18 September 2019 - 10:41 AM

I can’t speak to the Moonlite but I use a Feathertouch focuser on mine and a Tele Vue binoviewer BUT I also use the 1.25x GPC and 1.25”  T2 system. The T2 system is mandatory. Without it you won’t come to focus. 

One other question. In one of the older threads I thought you posted a pic of your Mewlon with the Tak universal R&P focuser. Are you still using that? Just making sure your setup is utilizing that focuser since I did consider that one as well. Thanks. 



#6 dr.who

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Posted 18 September 2019 - 11:01 AM

One other question. In one of the older threads I thought you posted a pic of your Mewlon with the Tak universal R&P focuser. Are you still using that? Just making sure your setup is utilizing that focuser since I did consider that one as well. Thanks. 

I replaced the focuser on my Mewlon 250 with the Feathertouch one. I don't like the idea of a critical component failure making a very expensive telescope unusable. When Takahashi discontinued the support for the German made DC motor on the original Mewlon focuser that happened to a friend of mine. It was the Devil's own business finding a way to get it fixed. I have moved the focus on the 250 to the point where the FT can take over for all my EP's and BV.

 

I can and do switch the FT between the 250 and 210. Sadly while the optics are excellent on the Mewlon line, as with all the other telescopes from the 60mm FC-60 to the 150mm/6" TOA, Tak doesn't do a good job on the focuser assembly. In the 210 this can mean mirror flop. On mine it is present but not so bad as to be annoying. But because the swap is very simple it is one that I do. All of my Takahashi telescopes have a FT focuser or pinion on them. 



#7 dr.who

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Posted 18 September 2019 - 11:06 AM

The T2 system from Baader is almost a must have with BV's if you want to be as close to native focal length as you can get. And to take care of any Spherical Aberration it is best to use at least a 1.25x GPC even if you can reach focus natively. My T2 system is: 2" nosepiece -> 1.25" Amici Prism Diagonal -> 1.25x GPC -> Tele Vue Binoviewer threaded onto the other end of the diagonal. This system lets me reach focus on everything I have.



#8 ckwastro

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Posted 18 September 2019 - 11:45 AM

Perfect. Thanks for explaining all of that.

 

Agreed. Tak focusers are not that great. 




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