Yesterday, the Parks 12.5" f/4.8 OTA that's been sitting in the corner of my garage for six months finally got some of the care and attention that it deserved, and a first real test under the stars. I'd had this scope out a couple of times previously but last night constituted its real "first light".

First, it had a godawful smell from cat pee (yes indeedy!), so I disassembled everything and gave all the non-optical components a good wash with diluted ammonia. I also gave the back and sides of the primary a similar wash. That pretty much did the trick, although you can still get a whiff of the OTA's "history". And while I had the primary out, I center spotted it.

Next, I repaired the spider. One of the split bolts at the end of a vane had broken. This was easily remedied with a pencil eraser pulled from the end of a pencil. I routed a hole in it with a pushpin, then forced it onto the small shaft to hold the spider vane in place. It worked like a champ.

The secondary holder bolt that slides through the spider is only 1/4" in diameter, too thin to hold the 3.2" secondary and holder securely. But I managed a "fix" for that, too. I filled up the space on the bolt between the secondary holder and the spider by putting a nut on it. Fortunately, this spaced it precisely underneath the focuser, and buttressed it enough to provide a great deal of extra rigidity. Woila'!

I replaced the cork supports on the primary cell and also replaced the push bolts with thumbscrews. Once I had everything reassembled, I proceeded to collimate the scope using a Tectron peep sight and then a Tectron Cheshire ep. (I couldn't seem to get adequate illumination to use the autocollimator.)

Finally, I jury-rigged a quick 'n dirty mounting to hold this OTA on my Losmandy GM100 mount. I had called Scott Losmandy a month ago to ask if he thought the mount could handle this 60 pound OTA for astrophotography. Unfortunately, he felt that the length combined with the weight would make it too much for this mount to handle, but I was eager to check it out.

The mounting consisted of a pair of "radiused" (is that a verb?) wood blocks attached to a board. I screwed a Losmandy dovetail plate onto the backside of this board. Once this assembly was atop the GM100 and in a horizontal position, I attached the OTA to it with a pair of nylon compression straps. As I slowly aimed the OTA upwards, I began to hear some slippage, so I quickly moved it back to horizontal and wrapped a pair of bungie cords around the equ head and clipped them to the bottom of the OTA. That worked great, too great in fact, because whenever I loosened the straps to rotate the tube, they pulled the up a little and, messing with the balance. Oh well, that was a small price to pay for the added security.

So now, the entire assembly was ready to try on Luna and the stars. Unfortunately, the seeing was crap, and at first the mirror was not fully cooled (how long does it take a 12.5" x 2.25" mirror to cool, anyways?). I had fun poking around the edge of the moon, but it was difficult to tell how the optics would perform. Next, I tried splitting Rigel. Although it was pretty mushy due to the seeing, the companion was an easy sighting. Then I went to the Trapezium. Likewise, the four brightest components were mushy, but "e" was coming and going from the party, and "f" was an occasional attendee.

(BTW, Parks uses the same 15.5" diameter fiberglass tube for their 12.5" and 14.5" scopes, so the tube is somewhat oversized for this mirror. I suppose this helps with both mirror cooldown and currents, but it adds weight and I wonder if it necessitates a larger secondary due to the focuser being further out from the optical axis.)

I went inside for a while, to let the mirror cool some more and to see if the seeing would improve. There was some improvement. The edge of the moon was great fun. The contrast wasn't great - moisture in the air? But the sharpness was very good when the air stilled. I went back to the Trap, and now "f" was steadily visible along with "e". I even easily found M81 much to my surprise at 44x.

I fine tuned the collimation on an out of focus star image, and the images improved a bit. The air wasn't steady enough to do a star test but the stellar images seemed very good and the moon was crisp and clear when the air stilled. Castor was also an easy split, with lots of dark space between the pair.

The mounting was plenty stable at 230x for visual use, and I plan to try it for photographic use as well. Fabricating a better mounting system will improved stability. I think it will be fine for short exposure photography as long as there isn't more than a slight breeze. And it might be killer for CCD work.

Does anyone have ideas or plans for making a mounting collar or rings out of wood? I hate to spend big $$$ on mounting rings.