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Home > Reviews > Telescopes > Refractors > Orion 120mm f/8.3 Refractor OTA

Orion 120mm f/8.3 Refractor OTA
By Michael Tencza - 10/9/2006

This past Valentine’s Day I received a 114mm reflector telescope on an equatorial mount as a gift. My wife got a great deal on it from a local camera store and thought it would be fun. Long story short, my interest grew quickly and I began searching the net, reading astronomy books, talking to more experienced people, and ended up pushing my little reflector as far as I could. This included better lenses, red dot finder, tube rings, and more. I also had some good fortune along the way. The EQ1 mount that came with the scope was defective, eventually broke beyond repair, and Meade replaced it with an EQ2 mount (a far sturdier piece of equipment) for no cost. Also I consulted with a friend about my unsteady tripod and how difficult it was to focus at higher magnifications. Being a former surveyor he just happened to have a sturdy wooden tripod that was idle and without much trouble we were able to attach the EQ2 mount to it. This new mount and tripod setup provided a very stable platform for my small reflector. This satisfied me for a while, but since most of my viewing was of the moon and planets I began to research refractors.

What I wanted was a telescope with the following:
1) Low expense and maintenance/adjustment
2) Not too much to buy beyond what I already owned
3) Not too heavy and relatively portable
4) Quality views of the moon and planets.

After reading mostly favorable reviews about the Orion 120mm f/8.3 achromatic refractor I decided to purchase one. Reviewer statements like “most bang for the buck” and “I can’t think of a better way to spend $ 300.00” appealed to me. There was also little for me to buy beyond a star diagonal and finder scope. Shortly after I became interested in this model one came up for auction online (OTA and rings only) and I jumped on it. It arrived quickly from the previous owner in its original packaging. Except for a few scratches on the body of the optical tube (described by the seller prior to the sale) it was in very good condition. I read about the use of a very sticky grease used on the focuser in a review and cleaned and replaced the lubricant as recommended. I also noticed some debris (small bits of dry white material) on the inside and outside of the main objective.

A quick call was made to Orion Customer Service (very helpful and pleasant to deal with) and I learned the objective housing could be removed from the optical tube without jeopardizing collimation to remove the debris from the inside surface of the objective. I removed all the loose debris from both surfaces of the lens with gentle puffs of air blown from a new, small baby nasal aspirator. I then ordered the parts I needed from Orion as I was already impressed with their customer support. This included their 2” dielectric mirror diagonal, 9x50 finder scope and also an extra counterweight. Another item I did not take into account was the mounting plate. After seeing the size of the telescope first hand I realized the one I had was too short. This was solved again by my surveyor friend, who is also an accomplished machinist. We purchased an appropriately sized and shaped piece of aluminum stock and made the mounting plate to accept the telescope rings and attach to the Meade EQ2 mount. When the parts arrived from Orion and the mounting plate was ready I quickly put the system together and it was ready to use except for one thing. Tropical storm Ernesto was passing through North Carolina and as others have reported so many times in the past the “new telescope curse” was upon me.

Finally, after about a week, I was able to get a quick glimpse of the moon through a break in the clouds. First however I would like to point out that just as Orion had led me to believe, collimation was not affected when I removed and replaced the objective housing for cleaning purposes. While I can not claim to be an expert at judging collimation, stars placed slightly out of focus in either direction look as the manual states and focusing objects at high magnification is very easy. The lenses I use are a 32mm plossl and orthoscopic lenses at 12.5mm, 9mm, 6mm, and 4mm focal lengths. I am pleased to report that my first glimpse through a telescope of this quality was just breathtaking. The 32mm showed excellent detail on the whole surface of the moon and with what seems to me a minimum of false color. The chromatic aberration described by others concerned me as I was researching refractor telescopes but the amount present with this particular model does not detract from viewing for me at all. Several days later I was able to get a view of Jupiter and was equally impressed. The equatorial bands were seen easily as well as the polar caps. Again the image was sharp and easily focused at 250x magnification with my 4mm lens. I apologize for the lack of technical details but I am new to this hobby and have a lot to learn.

Conclusion

The Orion 120mm f/8.3 achromatic reflector has satisfied all of my requirements for a telescope and then some. I do not believe I could have done better in a refractor of this size and for the price I paid and feel the $ 299 retail price is a bargain. Most importantly I am very happy and enthusiastic about using this telescope and do so whenever the skies are clear. Maybe someday the bug will get me for motorized tracking and photography or aperture fever, but until then I have no complaints. Everyone should have the same positive experience I have had with this activity so far.

Click here for more about this subject. -Ed.

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