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Image train ES102 with reducer

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#1 mbett

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Posted 06 April 2021 - 12:09 PM

Hello. I have an ES102, extension tube, Stellarvue .8 fffr, 2” filter, Hotech T adapter, T ring and Canon T3i.

Few questions: the reducer has threads on the extension tube side. The extension tube doesn’t have threads. Is it ok that the reducer is just inserted into the extension and snugged with screws? Lots of camera weight hanging off the end...

I’m not sure about the Hotech adapter either. It doesn’t seem to mate to the reducer.

Curious if I need some sort of adaptor or spacers.
On another site, I was told someone had a custom adapter made. Are there retail options?

Thanks

#2 B 26354

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Posted 06 April 2021 - 12:18 PM

Seems kinda odd that the extension tube isn't threaded on both ends. I have many for my ES 102CF, and every one of them is.  confused1.gif



#3 mbett

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Posted 06 April 2021 - 12:33 PM

Trying to post a few images...

Attached Thumbnails

  • EDFB8434-4236-49AD-AD52-1F151DAC9279.png
  • ECE0BA3B-B128-4AB0-9D56-9EA3403AC9AE.jpeg
  • F6318901-8FCB-40E0-BA0A-356C0FE47692.jpeg

Edited by mbett, 06 April 2021 - 12:36 PM.


#4 ShortLobster

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Posted 06 April 2021 - 01:29 PM

It appears that some of the ES102's extension tubes are threaded and some are not. Mine is not, and I have the same imaging train as you. The Hotech has a self-centering mechanism that keeps it centered. The SV ff/fr does not, and my images are slightly vignetted on one side, and are probably slightly out of focus on one side. Doesn't really bother me, but YMMV. 



#5 mbett

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Posted 06 April 2021 - 01:41 PM

Thanks. So do you have extension tube>SV ff/fr>T ring > camera?

If so, is there a problem using the screws vs threads? (Just makes me a little nervous.)

Have you used a 2” filter with your setup and how did that affect back focus?

#6 ShortLobster

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Posted 06 April 2021 - 03:19 PM

I use a cooled astro camera, My full train is:

 

scope > extension tube > Hotech FF -OR- SV ff/fr > OAG > filter wheel > ASI183mm . Backfocus is 55mm. 

 

I would prefer to thread the FF into the extension tube, to reduce any droop, but I haven't found a part for that. I found that the SV needs to be pushed into the focuser to overcome a small step, at least in the version I have. 

 

I get good round stars in the corners regardless of filter with the small sensor in my ASI183. Not sure how it would work with your larger sensor. 



#7 mbett

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Posted 06 April 2021 - 03:33 PM

Thanks for that. FYI, on another group a fellow couldn’t find the attachment and ordered a custom one from here https://preciseparts...///adapter.html. Took 60 days. Not sure of price. I have an email in to ES to see if there are other options. 



#8 mbett

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Posted 06 April 2021 - 07:26 PM

The kind people at Stellarvue were very responsive. They mention the threads weren’t necessary. “the threads we're seeing here just below the part that says "Stellarvue 0.8x" in the image are m54, which works with some of our rotators like those we used to include on our SV(X)70 and SV(X)080 scopes. These are not threads that Explore scientific has ever used to my knowledge, so you are not missing anything. Just push it in like you're doing and that should work fine! The "nose-piece" to which I referred is indeed the part tucked into the focuser drawtube (or rather to the extensions coming off the drawtube), which you have pointed to in red. This is how we traditionally recommend using the SFFR102 with explore scientific scopes as it avoid the issues I mentioned in my first email of the threads sometimes fitting and sometimes not fitting.“


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