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New small refractor

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#1 psuaero

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Posted 01 December 2019 - 02:59 PM

Xmas is coming and I've got the bug for new gear. I bought my first scope (NexStar 6SE) in June. Immediatley began taking pics and video, stacking, etc. I picked up a used Orion Sirius EQ-G (Eq-mount) in late September for the better pointing. Now, Xmas is here and I'm hoping to purchase my first refractor for wide-field DSOs and to keep my learning curve moving forward with guiding.

 

I've narrowed it down to the Astro-Tech AT72EDii or the Apertura 72mm APO doublet. I believe these are the same scope (does anyone know for sure?). If that's true, then I'm cleaning toward the Apertura. Price is the same but Apertura seems to have a much better warranty than Astro-Tech. Both are out of stock right now so I'm waiting to hear if either will be available for Xmas.

 

I'm going to pair this new short refractor with a 50mm guide scope (probably a William Optics) and a ZWO ASI120 Mini. If I've done my homework then these along with my mount should give me a more effective astro-photography platform than my longer focal length SCT.

 

So, next question is about the field flattener and 0.8x reducer/flattener. Is either necessary, should I get one right away? I don't know that I need shorter than 430mm FL but the F4.8 might be helpful. For the time being I'll be using my old Canon T2i (550d).

 

Comments, suggestions, criticism? Help me spend my money (which isn't in endless supply).

John


Edited by psuaero, 01 December 2019 - 03:09 PM.

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#2 Auburn80

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Posted 01 December 2019 - 03:08 PM

For AP, a short refractor needs a flattener - especially with larger chip cameras. A reducer is desirable to make your system faster but is not a requirement. Remember though, an f stop difference doubles/halves exposure times.
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#3 psuaero

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Posted 01 December 2019 - 03:12 PM

Thanks Auburn80. I just realized that I forgot to include what imager I was using. I came back to add that piece of info. and saw you'd already replied. So, in your opinion the FF/reducer is a better investment? Moving from 430 to 344mm isn't huge but the added benefit of shorter exposures between F6 and F4.8 is important, even with guiding?


Edited by psuaero, 01 December 2019 - 03:40 PM.


#4 sg6

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Posted 01 December 2019 - 03:37 PM

Get the flattener (reducer/flattener). You will want one for AP so if budget allows just get it now. You have it then.



#5 Auburn80

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Posted 01 December 2019 - 03:53 PM

Shorter exposures can help avoid a number of unpleasant effects. It can reduce trailing from misalignment, lost subs due to aircraft or satellites, occasional vibrations from wind or errant feet. But only you can decide whether the fov/fl is to your liking.

#6 drd715

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Posted 01 December 2019 - 09:05 PM

Xmas is coming and I've got the bug for new gear. I bought my first scope (NexStar 6SE) in June. Immediatley began taking pics and video, stacking, etc. I picked up a used Orion Sirius EQ-G (Eq-mount) in late September for the better pointing. Now, Xmas is here and I'm hoping to purchase my first refractor for wide-field DSOs and to keep my learning curve moving forward with guiding.

I've narrowed it down to the Astro-Tech AT72EDii or the Apertura 72mm APO doublet. I believe these are the same scope (does anyone know for sure?). If that's true, then I'm cleaning toward the Apertura. Price is the same but Apertura seems to have a much better warranty than Astro-Tech. Both are out of stock right now so I'm waiting to hear if either will be available for Xmas.

I'm going to pair this new short refractor with a 50mm guide scope (probably a William Optics) and a ZWO ASI120 Mini. If I've done my homework then these along with my mount should give me a more effective astro-photography platform than my longer focal length SCT.

So, next question is about the field flattener and 0.8x reducer/flattener. Is either necessary, should I get one right away? I don't know that I need shorter than 430mm FL but the F4.8 might be helpful. For the time being I'll be using my old Canon T2i (550d).

Comments, suggestions, criticism? Help me spend my money (which isn't in endless supply).
John

Consider a zwo asi 290mm mini instead of the 120 mini. It is more sensitive.

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