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Orion's 120mm Telescope Setups

Posted by Blair Slayton   12/27/2004 12:00AM

In the past couple of years I have used each of Orion’s 3 offered setups for their 120mm scopes and a couple not offered by them. Here is an overview of each.

SkyView Pro 120mm EQ:

My first suggestion is to buy the Skyview Pro Mount Extension because without the extension looking at the apex of the sky is difficult as the eyepiece gets very close to the ground even when the tripod is fully extended. Sitting comfortably while viewing is difficult even with an adjustable chair. Putting extra weight on the focuser can help some but I still recommend the extension.

Astroview 120mm EQ:

I can not recommend this setup because at higher powers the mount vibrates too much for me. Also, the problem of the eyepiece getting close to the ground when looking at the apex of the sky is an even bigger problem with this mount and no extension is available for it. A taller, wooden tripod may be available from a vendor other than Orion to help with this problem but then this extra cost may make buying the SkyView Pro version a better deal.

Astroview 120ST EQ:

For rich field viewing and for powers of 100X or less this is a very good setup. This scope is an f/5 versus f/8 of the above mentioned setups and is not as good performer on the planets and Moon as the f/8 but with a 2 inch 50mm eyepiece all of Cr70 (Orion’s belt area) is viewable. This setup does still suffer from the apex problem but not nearly as bad as the f/8 setups. If you have an adjustable chair viewing while sitting down is not difficult. This setup does suffer some vibration problems when the legs are fully extended but nothing like the Astroview 120mm EQ.

120ST on the Skyview Pro Mount:

This setup is not sold by Orion and I am not sure why as this is much more comfortable to use and stable setup. This mount is taller when fully extended than the Astroview mount fully extended and is a much more stable mount as vibration is minimal. Also, sitting comfortably while viewing the apex of the sky is not difficult with an adjustable chair. This is a more expensive setup since you have to buy the OTA and mount separately. I liked the Skyview Pro mount so much more than the Astroview mount that I sold the f/8 OTA and the Astroview mount (separately) on Astromart and then bought the f/5 OTA to use on the Skyview Pro mount.

After trying both OTAs I find I like the f/5 version best as I prefer low power viewing (100X or less) which is somewhat influenced by my typically high humidity, light polluted skies; Mag 3 to 4 is my typical seeing in North Carolina. I’m pretty much restricted to the brighter Messier and Caldwell objects.

As far as photography with these setups I can not say from experience, as I do only visual observing, but I would have to say, because of its stability, the 120ST on the Skyview Pro Mount would probably be the best setup. Dual Drives are available from Orion for the Skyview Pro Mount.

Also, I use the 120ST on a Vixen Custom D mount which, unfortunately, is only available used these days when you can find one. I prefer this setup for quick looks and when I want to look directly South or North as equatorial mounts are a bit of a pain when used this way. I know of one person that was happy using the 120ST on Orion’s AZ-3 mount. I found that I had to tighten the azimuth bolt so much to keep the scope from toppling backwards that the azimuth motion was too stiff for me. On the Custom D mount (being a heavier duty mount than the AZ-3) the azimuth motion is not so stiff but then it can cost $300 used while the AZ-3 is $149 + shipping new. It is very possible that if you are more mechanically inclined than I you will not have this problem with the 120ST and the AZ-3.

Blair Slayton
December 2004

Click here for more about the Orion SkyView Pro 120mm EQ Refractor with Single-Axis Drive. -Ed.

Click here for more about the Orion AstoView 120 ST EQ. -Ed.