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Putting Together a Solid Orion 80mm ED System

Posted by Edwin Kessler   06/07/2004 12:00AM

Putting Together a Solid Orion 80mm ED System
by Ed Kessler

Being the owner of a Celestron 9.25” SCT, I wanted another scope that would be very portable, relatively lightweight and easy to set up (or keep set up) for quick observing. I also wanted a scope that would perform well at relatively high powers for lunar, solar and planetary viewing, but could also do a good job with wide field views at low power. The obvious solution was a high quality refractor in the 80mm – 100mm range with a moderate focal length. The next obvious fact was that the apochromats from Takahashi, Tele Vue, Stellarvue and others would perfectly meet those goals. Unfortunately, those scopes were out of range for my budget. So having read Tom Trusock’s very favorable review of the Orion 80mm ED, on Cloudy Nights Telescope Reviews, “An Affordable APO: The Orion 80mm ED,” and having finally found the little scope in stock at Kendrick Astro Instruments, I plunked down the $499.00 plus shipping and ordered one along with a set of rings for an EQ-3 mount. The f/7.5 system is a good mid-range focal length and with my 5mm – 15mm plossls and RKEs and 2.4x barlow I can quickly achieve the scope’s highest theoretical magnification of 165x. And with my 32mm 2” Konig I can scan the heavens with an actual 3.2 degree field of view.

While waiting for the scope to arrive, I also followed Trusock’s advice and picked up a Williams Optics 2” diagonal, a compression ring visual back by Mercury Systems (from ScopeStuff), a red dot reflex finder and solar filter from Orion, and a used EQ-3 mount. I also ordered a refractor collimating eyepiece from ScopeStuff, wanting to be prepared for every contingency, but hoping that I wouldn’t need to use it.

Improving the EQ-3 Mount
The EQ-3 mount was the first item to arrive and that gave me time to rebuild the mount as vibration free and solid as possible. In anticipation of being disappointed with the aluminum legs, I had ordered a set of wooden tripod legs from Hands On Optics. At $49.00 these legs are definitely a bargain. They are constructed of painted mahogany and come with a plastic spreader tray. Apart from the plastic tray and its corresponding plastic hinge mounts all the hardware is steel and painted black. The tray is the only weak part of the unit but it should suffice. Alternately, and this is in my future plans, one can make a homemade wooden or metal tray. The wooden legs from Hands-on-Optics fit the EQ-3 tripod head perfectly. This foresight proved to be accurate. Those aluminum legs resonate vibrations for quite a while even though all the hardware was tightened as snuggly as I dared. The wooden legs also provide the benefit of additional height without sacrificing stability.

The equatorial head of the used mount moved freely and smoothly so I didn’t need to dissemble it for a re-lube job, and I calculated that the mount could adequately handle the approximately 24” of telescope tube and the approximate 7-8lbs of weight (including the diagonal and finder scope), at least for visual observations at higher powers. However, the die cast aluminum tripod head seemed inadequately light and feeble. For increased strength and to add another 1.5lbs of stability I filled the entire tripod head with Kevlar reinforced epoxy designed for repairing metals. To save on epoxy costs, to strengthen the epoxy bond and to provide the additional weight I mixed in 100 5/16” nuts as I filled the cavities on the underside of the head. This gives the tripod head a good solid feel. I suspect that it dampens vibrations as well since the aluminum head is no longer hollow. I’ve been tempted to fill in the base of the EQ-3 head itself but haven’t taken that step yet. To be safe I allowed forty-eight hours for the epoxy to dry before I reassembled the tripod. Together, the equatorial head and wooden tripod weigh in at about 28lbs (this includes both of the four-pound counterweights). Surprisingly, Orion lists its Astroview Mount at 27lbs. I’m assuming that those specs include both four-pound counterweights, but considering the tremendous increase in stability from my modifications, my mount weighs only one pound more. That puts the total weight of the system at about 35lbs – a nice weight to carry to the backyard for impromptu observing sessions.

The Orion 80mm ED
Having never owned a Synta, or other Chinese scope for that matter, I was anxious to see how the mechanical and optical systems compared to the Tele Vue Genesis SDF that I once owned. The reviews pointed to minor irritants in the mechanical finish and to the Orion’s excellent optics. Arriving in a double box which was padded with Styrofoam inserts, the first visual inspection revealed only one immediate blemish. The lens shield had been buffed and repainted at two spots but the job was not very good. The shield itself slips over the front lens assembly and fits snuggly, but I would be more comfortable with a better mechanical connection. In one of Tom Trussock’s reviews he mentions that the lens itself worked loose after an observing session. So I checked the tightness of the ring that holds the lens assembly in place. Sure enough it was loose! I tightened it down and made a mental note to check it each time I use it. Otherwise, the scope’s appearance is quite acceptable. It has a more “solid” feel than I expected. The focuser exhibits no instability when cranked completely out and the focusing itself is quite smooth all through its travel except for one “bump” when moved to its innermost position.

I mounted the scope on the EQ-3 and again gave myself a pat on the back for buying those wooden legs. The setup is quite stable. Vibration dampening times tested at right around two seconds which was a little better than I expected.

One minor glitch that I had was that the Mercury Systems’ visual back did not fit although I had ordered the unit specified for Synta refractors, including the 80mm ED. A quick call to Jim Henson indicated that this was the first time that this was an issue for him and that he would send out another unit, hoping that the issue was a thread problem with the visual back rather than with Synta changing thread specs on their scopes. Alas, the second visual back fit identically, meaning it didn’t! Jim Henson instructed me to clean the threads on the focuser tube with a wire brush but that was to no avail as well. Nonetheless, Jim was absolutely a pleasure to deal with and quite accommodating. I highly recommend Scopestuff as a very reputable company.

Actually, trying to fit the Mercury Systems’ focuser adapter proved to be more of a fiasco than I wanted to deal with. I applied a tad bit too much torque while attempting to screw on the adapter and put a small indentation in the focuser tube itself! The focusing rod of the scope is steel while the tube appears to be fairly soft aluminum. Any amount of torque applied to the tube which then presses it against the focuser rod has the potential to slightly dent the tube. The result was an annoying “bump” in the focuser as it moved across the indentation. I probably broke all of my warranty rules with Orion doing this, but the fix was to take some very fine emery cloth tightly wrapped around a flat file and buff the entire length of the focuser rod bearing surface on the focuser tube. Then I took some very fine Scotchbrite and, using the file as a flat surface guide, buffed the surface to a mirror finish. I was really surprised at the result. The focuser is now smoother than before! The moral of this little story is to always take the focuser tube out of the telescope before applying any torque to the visual back, even to tighten the original. Just a small amount of torque is a risk to the smooth action of the focuser.

Next up was the collimation test. Gulp! Some of the reviews stated that many of Orion’s 80mm ED’s were delivered out of alignment and that the only way to correct the alignment would be to adjust the focuser to match the optical path of the lens. I inserted the Scopestuff’s refractor alignment eyepiece and hesitatingly took a peak. To my delight, I saw two concentric circles! My scope’s alignment was as near to perfect as I could estimate and I decided that any “tweaking” would only make things worse.

The first visual test of the scope was during the daytime and I focused on a mountain about a mile from my house with a Tele Vue 26mm plossl eyepiece. The trees did indeed snap into focus and the view was crisp and clear – good indications that it would do well after dark. True to my astronomy fortune, the first night out was completely overcast. I took the scope out anyway and tested it on distant tower lights (about 20 miles away). At 23x (26mm Tele Vue plossl) and 40x (15mm Tele Vue plossl) the Orion 80mm ED provided sharp, color-free images that came abruptly into focus. I retired for the evening praying for clear skies and very anxious to test the scope on the bright moon and Jupiter.

On the Monday prior to the Venus transit I had the opportunity to view the sun, using the Orion solar filter. Initially, I set up using my Tele Vue 26mm plossl (23x) to find the sun and center the image. At this magnification everything was crisp and clear, but small. Boosting the magnification to 40x with my Tele Vue 15mm plossl provided an actual FOV of 1.25 degrees, framed the sun quite nicely, and showed the structure around the largest sunspot. However, just a few small sunspots were visible so I decided to experiment with various eyepieces and eyepiece/barlow combinations. The best views (in my eyes) at higher power were through my 2.4x Brandon Dakin barlow and my Edmund 15mm RKE at 96x. The Tele Vue 15mm plossl performed identically in terms of contrast, but gave a more gold/yellow tone while the RKE yielded a more white/greenish image. The barlow and my 8mm RKE or 8mm Tele Vue plossl at 180x pushed the little scope just a tad too far. The contrast was still quite acceptable, but focusing was troublesome. Experimenting with a 5mm Ultima plossl, a 4mm Meade plossl, and 16mm or 9mm Tele Vue Naglers did not quite provide the same contrast as the barlow/RKE combination.

That evening I took the scope out for its first run with the night sky. Conditions were fair since I was competing with my neighbor’s garage lights. Why do they need to keep those things on all night? Seeing and transparency were fair to good, definitely not the best night. I could not detect the Milky Way as I usually can. Nonetheless, I took a look at Jupiter. After experimenting with a variety of eyepiece/barlow combinations, I settled on the small, crisp view that my 8mm RKE provided at 75x, anything higher did not improve the view. I could see the equatorial bands clearly and some shading at the poles, and even had a glimpse of the Great Red Spot during times when the seeing improved. There was absolutely no hint of color even at 180x but the resolution fell off at that extreme.

To do a star test I centered Vega in the field of view at low power and the popped in my 4mm Meade plossl which provided 150x (near to the theoretical limit of the scope). There was a bit of blue color noticeable on the outer diffraction rings on both intra and extra focus as was expected, but when focused the scope displayed no noticeable color to my amateur eye. The diffraction rings were perfectly concentric and very well defined, actually fascinating and fun to view. I could not detect any signs of other aberrations.

The next test consisted of widefield views using my 2-inch 32mm Konig at 19x and a 3.2 degree FOV. The star fields were sharp and clear and the views reminded me of my Tele Vue Genesis at low power.

Finally, I took a peak at Albireo, The Scout Double, to test the color resolution of the scope. With the Konig both Beta-1 and Beta-2 looked like colorful jewels in the sky. I’ve always loved this double. Then for kicks I pushed the scope to 150x to see how the scope would fare. Again, both stars showed wonderful color and focused sharply.

Here is a breakdown of the cost of my system to date. I may add an R.A. drive in the near future, but other than that, the setup is complete. Is it worth $947.00? Every penny! As a grab-n-go scope the Orion 80mm ED fits the bill perfectly. Its versatility assures that I will be using the scope often.

Breakdown of the Cost of My System
Used EQ-3 Mount (the mount was originally $180.00, but I was able to sell the hardware from the original aluminum legs for $30.00) - $150.00.
Wooden Legs from Hands-on-Optics - $49.00.
Epoxy and Hardware - $10.00.
Orion 80mm ED - $499.00.
Used Wiliams Optics 2” Diagonal - $120.00.
Refractor Collimating Eyepiece - $15.00.
Orion EZ Finder Reflex Sight - $34.95.
Orion Solar Filter - $69.95.
Total Cost - $947.90.

Note: While I am not affiliated with any of the venders mentioned in the article, I can recommend all of them as a satisfied customer.

Click here for more about the Orion ShortTube™ 80mm Rich-Field Refractor. -Ed.