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Bushnell 90mm Mak - Focal Reducer / Field Flattener

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#1 jawats

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Posted 22 May 2024 - 09:00 AM

All,

 

I purchased a Bushnell 90mm mak used recently, with mount and tripod. Mount aside, I want to use it for some astrophotography, and am considering a field flattener and reducer for my Pentax FF dSLR. Any recommendations for one (combined) or both? Thank you!

 

--J.



#2 Tapio

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Posted 22 May 2024 - 10:24 AM

Mak scopes are really best used in solar system object viewing/imaging.

They are so 'slow' that even reducer wont make them 'fast'.

 

Some have used a f/6.3 reducer in Mak scopes but there's  optical difference  so not optimal.

https://www.cloudyni...-focal-reducer/

 

Other have tried AP CCDT67.

https://www.cloudyni...-focal-reducer/



#3 GoldSpider

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Posted 22 May 2024 - 02:07 PM

All,

 

I purchased a Bushnell 90mm mak used recently, with mount and tripod. Mount aside, I want to use it for some astrophotography, and am considering a field flattener and reducer for my Pentax FF dSLR. Any recommendations for one (combined) or both? Thank you!

 

--J.

You're kinda trying to fit a square peg into a round hole here.  A Mak will work for solar system imaging, and you may even be able to get workable images of globular clusters and bright planetary nebulae.  But for more than that, a Mak is not the right tool, and you can't spend a reasonable amount of money trying to make it so.


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#4 jawats

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Posted 22 May 2024 - 09:54 PM

You're kinda trying to fit a square peg into a round hole here.  A Mak will work for solar system imaging, and you may even be able to get workable images of globular clusters and bright planetary nebulae.  But for more than that, a Mak is not the right tool, and you can't spend a reasonable amount of money trying to make it so.

So, not even a field flattener for use with my dSLR? 



#5 Tapio

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Posted 22 May 2024 - 10:06 PM

Maksutov telescope typically have pretty flat field so you don't need a flattener.
But especially with DSLR you may experience vignetting (depending on attachment).
Flats will help some.
Just go and experiment what you get and what you like.

#6 bignerdguy

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Posted 23 May 2024 - 02:06 AM

But especially with DSLR you may experience vignetting (depending on attachment).

FYI the 90mm MAK's generally have a small internal aperture and thick baffles or no baffles and bad light reflection issues so for DSO's this isn't a good scope but for planetary it is good.  Also for a DSLR this is going to restrict the image diameter since the exit aperture of the MAK will not cover the entire sensor on the camera and you will see significant vignetting as a result.  Even the APS-C cameras will this problem.  If you want to do wider field DSO's an 80mm to 120mm Refractor would be better or a SCT or something comparable for higher power and more light gathering. SCT's can be expensive though but they work similar to MAKs except the secondary is not silvered onto the corrector and is adjustable. 




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