Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
Home / Orionís Astroview 90mm f/10 Refractor
by Blair Slayton 03/29/03 | Email Author

I have bought and tried many of Orionís refractors (ShortTube 80, ShortTube 90, Astroview100, and Astroview 120ST) and found the 90mm f/10 the most useful. Its 910mm focal length provides very useful powers for most types of beginner to intermediate levels of observing. With a 10mm eyepiece, and Orionís shorty barlow, Iíve been able to go to 182X on the moon, on some nights, and still clearly see the surfaceís detail.

Iíve watched Ioís shadow cross the face of Jupiter for the first time in my life. On some nights I can detect details in the Northern and Southern belts of Jupiter. Cassini Division on Saturn is usually seen very clearly. Iíve been able to see Rhea, a moon of Saturn, as well as Titan. All this in my backyard with streetlights all around and my 51 year old eyes.
Unwanted colors, like a purplish hue, have not been a problem. Beyond the edges of the Moon a slight purple ring (at higher powers) can be noticed if looked for. None have been noticed in the area where viewing is concentrated (like around the Moonís terminator). No purple-halo has been noticed around Jupiter like Iíve seen in the 120ST.

Orion sells this scope on a decent equatorial mount for $299. Vibration does become an issue at higher powers but things like using the scope on grass instead of cement will help. I owned a Skyview Deluxe (SVD) Mount that I bought from Orion to use with the above mentioned scopes and with the 90mm f/10 on it vibration is significantly reduced. I use it on this mount mostly but it performs well on the EQ3 mount that is supplied with it. Also, the EQ3 mount is lighter than the SVD mount. Normally, at worst, it takes about 3 seconds to settle down on the EQ3 after focusing on an object.

The focuser can be tricky to use at higher powers but this problem could possibly be fixed by taking the focuser apart and putting in a thinner grade of grease. With practice, Iíve been able to focus at higher powers very quickly without doing the mentioned modification to the focuser.

Iíve used a 32mm Sirius plossl, 25mm, 20mm, 17mm, 13mm, and 10mm Orion Explorer II (Kellner) eyepieces with this scope and have been pleased with their performance. Used with Orionís 2X shorty barlow this gives me a good range of useful powers.

I did buy Stellarvueís enhanced , 1.25Ē, 90 degree diagonal ($49) which states about a 98% reflectivity. A standard diagonal is usually around 89%. I realized about a 0.5 magnitude improvement for the magnitude of stars I could see through the scope. With higher powers (91X and above) I have seen down to 11.5 mag on average with this scope.

The computer program, The Sky (Student Edition) , Orion provides with their scopes is very handy but mainly for smaller scopes. Definitely 6Ē and larger scope owners will want to upgrade to a larger database version to have the program show the fainter objects and stars they can see.

I live in Greensboro, NC and humidity is usual fairly high so desert viewers should see even better performance out of this scope.

I also upgraded to Orionís 8X50 right angle, correct view, viewfinder which fits easily in the dovetail mount on the scope. I went to this because I can detect many of the Messier objects in it where with the supplied 30mm finder this was not true. Also, the right angle allows for more comfortable viewing when trying to find objects.

One problem with this setup is that when you wish to look at objects at the apex of the sky. Even with the mount fully extended (which increases vibration) the eyepiece gets low to the ground. Chair viewing becomes difficult unless you own one like Orionís Deluxe adjustable chair which allows you to raise or lower seat height as needed. A blanket on the ground will work as well.

If all the scopes perform like mine (Iíve read that these Chinese made scopes can vary in quality) then I highly recommend this scope. I feel this would be a much better beginner scope than anything smaller in aperture and a 6 inch or larger dobsonian. After the lure of the moon and planets wears off this scope will show more of the deeper sky objects than the smaller scopes and this scope is still light enough to move around and is easy to setup. It normally does not require to be collimated as long as it was done properly when made. The equatorial movement controls really help when tracking Jupiter at higher powers and there is a motor control option for the EQ3 mount from Orion.

Back to Top

Contact Us
CN Reports | Reviews | Articles | Forums | Classifieds | About Us
Copyright© 2004 Ad Libs Advertising.
Privacy Policy

Search Cloudy Nights
Advanced Search
Wednesday, July 30, 2014

Cloudy Nights Supporters


Cloudy Nights LLC