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Reducer for AT72EDII

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9 replies to this topic

#1 saptharishi

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Posted 24 July 2019 - 01:25 AM

Hi Friends,

 

I am planning to buy a 0.8x reducer for AT72EDII scope.  I see the following options, and the prices are different:

 

- Tele Vue 0.8X Reducer/Flattner for 400-600mm Refractors. (Televue TRF-2008 0.8x Reducer/Flattener)

- Astro-Tech 0.8x Reducer/Field Flattener for F/6 Refractors

- Orion 8894 0.8x focal reducer for refractor telescopes

 

Any thoughts on which one would be the versatile.  Televue TRF-2008 is double the price of the the other two options.  Does it worth spending the money on Televue TRF-2008.  Please let me know your thoughts.  If any of you have used these reducers or compared them, please post your experience. Thanks in advance.



#2 james7ca

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Posted 24 July 2019 - 01:59 AM

Do you plan on trying to use this for visual work? If so, that may not work that well since the backfocus is limited to something near to 55mm (probably for all of these). Thus, it may not come to focus with a 2" diagonal. I don't know, maybe you could place it after the diagonal but then the scope might not have enough focus travel.

 

See here for the optical path length for various diagonals:

 

  https://www.cloudyni...omparison-r2877

 

However, for imaging I'd just go for the Astro-Tech 0.8X reducer. The Tele Vue MIGHT produce better results, but unless you try both you'll probably have no way to know for sure (unless someone else has already done that testing with the AT72EDII).



#3 saptharishi

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Posted 24 July 2019 - 03:07 AM

Thanks so much James7ca.  I do you it for visual,  but I will remove the reducer while doing visual astronomy. Reducer is only for the imaging. 



#4 tonyt

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Posted 24 July 2019 - 05:31 AM

This scope is very fussy about reducers; I'd ask Astronomics for a recommendation - you may be better off with a flattener.



#5 saptharishi

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Posted 24 July 2019 - 06:24 AM

Hi Tonyt, When you say, it is a bit fussy, I guess you had some bad experience using the scope with the reducer.  Can you share your experience.Thanks a lot.



#6 tonyt

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Posted 24 July 2019 - 07:00 AM

I had the TS version of the scope and it didn't work well with the TS .8 reducer or the WO 6AII reducer. The 70mm f/6 triplets seem to work better with reducers. I guess more aberrations can be better corrected in the outer field with the extra element. In any case I suggest you don't buy a reducer until you can confirm that it works with your scope.



#7 Ed D

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Posted 24 July 2019 - 07:28 AM

I have used my ATR8 Astro Tech .8x reducer/flattener for a few years with my AT72ED and have gotten very good results.  Cameras used were my ASI290MC and Canon T3i.  No experience with any of the other equipment you listed.

 

Ed D


Edited by Ed D, 24 July 2019 - 07:28 AM.

  • johrich likes this

#8 johrich

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Posted 24 July 2019 - 08:46 AM

I also have used the ATR8 with my AT72EDII and have been happy with the results.  I use it with an ASI183MC cool and Canon SL1.

 

johrich



#9 kolsen

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Posted 24 July 2019 - 08:58 AM

FYI the ATR8 has been on backorder since January.  Astronomics says it probably won't be delivered until October.



#10 saptharishi

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Posted 25 July 2019 - 01:55 AM

Good to know that ATR8 works well with AT72EDII.  Given that the Televue version should also work with AT72EDII, since it is readily available I am tilted towards it.




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