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APO Tri or Quad Suggestion for Astrophotography

Astrophotography Beginner
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#1 ruamaya

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Posted 09 May 2021 - 01:42 PM

Hey everyone,

 

I am looking for an Refractor APO, either tri or quad, for astrophotography. Currently have a reflector telescope but wishing for a wider FOV. Any suggestions in the $1000 to $2000 range. Much appreciated. 



#2 ZL4PLM

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Posted 09 May 2021 - 02:01 PM

Askar FRA400 and focal reducer - lovely wide field pin point stars and crisp image - def recommended here 


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#3 calypsob

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Posted 09 May 2021 - 02:07 PM

The 76 EDPH and 94 EDPH both do really well with their dedicated reducers.  I own the 76

 

Here is the 76 with an APS-C ASI 2600mc . Spacing is maybe 98% perfect

50600849901_dbf81a37b9_c.jpgAbberation Inspector - ASI 2600MC - Sharpstar 76 EDPH by Wes, on Flickr 

 

Here is the entire image from the 2600mc

50447292063_0ed7336326_z.jpgMBM 54 by Wes, on Flickr

 

Here is Sony A7RIII Full frame. Spacing is not optimized and the t adapter obstructs the sensor at the edges. 

 

50587790932_defb56cca9_z.jpgAbberation Inspector of Sony/76EDPH by Wes, on Flickr

 

Here is the entire frame from the Sony

50587790862_1431d86f90_z.jpgSharpstar 76 EDPH with Reducer and Sony A7RIII by Wes, on Flickr


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#4 bobzeq25

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Posted 09 May 2021 - 02:12 PM

I have a Stellarvue version of this, which I believe they no longer sell.

 

https://www.teleskop...ertificate.html

 

https://www.teleskop...f-6-CF-Apo.html

 

Sample image below, better version here, with acquisition details.  Atik 460 EXM CCD.  FOV about 2 X 1.5.  My new 2600 camera would have captured the whole nebula.

 

https://www.astrobin.com/285813/B/

 

Another possibility, similar focal length, integral flattener, which is very convenient.

 

https://agenaastro.c...-refractor.html

 

Similar scopes to both above, of various quality, are sold under a number of labels.  I picked these as excellent quality.

 

ca neb v2a_small.jpg


Edited by bobzeq25, 09 May 2021 - 02:15 PM.


#5 EdDixon

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Posted 10 May 2021 - 05:07 AM

William Optics scopes are very good quality units.  Their GT81 is a triplet and goes for about 1500 USD.  THe flattener adds another $238 or so.  A couple of the online firms have them in stock.


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#6 ruamaya

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Posted 11 May 2021 - 11:11 AM

Thanks everyone so far for your suggestions and advice. 



#7 asanmax

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Posted 11 May 2021 - 11:38 AM

If you're looking for wider field of view, then some information about your camera sensor size would help a lot in determining the best FL of the scope.

You should be looking for the best match for your camera sensor size in terms of arcsec/pixel ratio.

Here is the calculator:

https://astronomy.to...calculators/ccd

 

Best ratio is typically 1-2 arcsec/pixel.

 

Quadruplets/pentuplets are a bit easier to use. But a good pair of a triplet and flattener or flattener/reducer will be producing amazing images as well.

Look for FPL53 or FCD-100 glass if you can afford those.



#8 tjz

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Posted 11 May 2021 - 02:10 PM

If you want wide-field, I would highly recommend the WO Redcat series. The Petzval design gives a nice flat field out to at least an APS-C sized sensor. I do see some edge deterioration on a full-frame sensor.

 

Here's an example of what you can squeeze into that nice wide field: https://astrob.in/1kcp6u/0/

 

I've added a DeepSky Dad / ZWO EAF kit for auto-focus and it is a solid and enjoyable piece of gear. I love it!

 

    Tom




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