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Celestron Astromaster 90mm review

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#1 Olivier Biot

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Posted 19 February 2012 - 06:35 AM

Celestron Astromaster 90mm review

By Mark Scott.



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Posted 19 February 2012 - 11:07 AM

Both the 80mm & the 90mm Synta Achro f/11 refractors are pretty darn good telescopes. I have had experience with both. Being nice and long & over the Sidgwick Standard cleans up CA reasonably well. It's too bad Celestron let the bean counters into the design team and opted for the cheapo non-standard finder & finder mount. The Sky Watcher versions do a bit better in that regard. I set my sister up with an AR90 EQ and she gets lots of use from it. I've used it several times when visiting and have been impressed with the optical quality. The Orion 9mm Expanse (or a clone) does quite well in that scope. Nice review, good luck with the scope.

#3 class 37

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Posted 19 February 2012 - 11:32 AM


Thanks. I think this will be a great scope for my son. I've found a couple of universal brackets for a finder since writing the review so no drilling (phew).

Thanks for the tip on EP's.
All the best,


#4 Maverick199


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Posted 20 February 2012 - 07:37 AM

Nice little write up Mark. Hope your son enjoys this scope.

#5 Rustie


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Posted 20 February 2012 - 09:04 AM

Nice review Mark. I have had the AM90 for a number of years now and been pleased for what i paid.
As far as the focuser and finder go, well they are easily changed to either the standard Synta 86mm rack & pinion or the GSO 86mm Crayford (single or dual speed). I changed mine initially to the R&P and then the 1:10 Crayford when one came up cheap on UK Astro Buy'n'sell. Nice easy straight swap out.
I also removed the built-in dovetail and replaced it with 90mm tube rings and medium dovetail. This makes balancing the scope much easier. And looks better.
Finally i also had some marks on the OTA which at first didn't bother but finally decided i needed to do something about. First option was a respray with some paint from Halfords. But settled on the easier option of a wrap from Ebay. So bought some Carbon lookalike wrap and fitted it to the tube.....looks awesome. With the focuser, tube rings and carbon, it looks a much nicer scope.
Also compared it to our ED100 and was pleasantly surprised how well it did. My son is over the moon with his scope.

#6 class 37

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Posted 20 February 2012 - 11:12 AM

Hi Russ,

Thanks for the information on improving the cosmetics I may just get the airbrush and compressor out in the future for a re-vamp. The information on the 86mm Crayford is very helpful, we'll see how the wee man gets on and look to do this in the future.

When deciding which scope to get him I looked at the SW 90, Vixen 80mm OTA and the Astromaster 90mm. He loves joining me when I'm out with the 80mm APO so I thought at £136 delivered I couldn't go wrong with the Astromaster, besides it gives me a CG3 for my 80mm for when we go up the hill's in the summer because the Vixen Porta mount is a bit cumbersome. The CG3 fits in my 85 litre back pack when the mount is off the legs. As I write this I'm thinking a new tent is on the cards too, that way I can take the wee yin.......happy days (well nights) untill the wife discovers my plan.

#7 oldtimer



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Posted 31 May 2014 - 10:12 AM

I fabricated an OTA using an astromaster 90mm lens and cell. It did not produce very good crisp images. I am experienced in colimation so that was not the issue. My 70mm f10 Meade consistly prodused crisper images. Maybe I just got a 'dud'.

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