Posts Made By: Rod Kaufman

Kwang, I agree with Mike and the holes you describe are fairly normal to find in mirror coatings. If you had many more pinholes appearing in clusters it would indicate a poor vacuum was used in the aluminizing process or the mirror surface wasn't properly cleaned prior to application of the film. I don't know any particulars of the "diamond brite" coating but it's probably a variant of an enhanced coating with, perhaps, a protective coat overlying the primary coating.

Gregg, I don't think you can go wrong with either eyepiece at F-10. If you had a faster scope such as my 16" F4.5, I would recommend the pentax eyepieces as they have no discernable aberrations at the edge of the field at moderate focal lengths. For example, my pentax 10.5 eyepiece shows a star at the extreme edge as a point with no pincushion,barrel or lateral color aberrations, coma or astigmatism at F4.5. Most amateurs don't believe this until I show them the image of a star at the center and then at the edge of the pentax unit and there's no distortion at all. At F-10, you might enjoy the larger field of the nagler but the 65 degree apparent field of view of the pentax is still quite nice to see most objects.

Brian, the safest method I've used is to apply the Zeiss cleaning fluid for muti-coated lenses. It comes in a small pump-spray bottle, costs about five bucks and is available from Astronomics or Anacortes. Simply spray it on and pad off the excess with a cotton ball. One bottle seems to last forever and it works quite well.

I have found my Discovery 12.5" mirror cell doesn't hold collimation because the springs in the mirror cell allow a small but significant amount of movement as evidenced by migration of the laser dot from the center of the doughnut to the top of the doughnut on the primary as the scope is moved from the horizontal to vertical planes. I believe virtually all such cell designs will produce this de-collimation effect when used with full-thickness mirrors. The "fix" is borrowed from an old Telescopics mirror cell-design which incorporated three locking screws with nuts that pass through the rear supporting plate to the plate that supports the mirror and are screwed-down after the wing nuts are adjusted for collimation. I drilled four holes through the back-supporting bars of the Discovery cell and passed the screws to the back of the plate that supports the mirror and tightened them after collimation. This effectively stopped the de-collimation. I believe the de-collimation problem is un-recognized by other amateurs and is probably a universal problem. I also think this explains why Ed Ting could not resolve Delta Cygni with a test 12'5" Discovery scope in the Novenber Sky and Tel review; his scope was de-collimating as he moved it but he didn't know it.

Craig,
One amateur reported that Novak had died. I do not know if this information is accurate.

Floyd,
I know how you feel--I have two weeks off from clinic duties at this time and I had hoped to do more observing. Nevertheless, happy holidays to you, your wife, Randy and all of the other guys in the Bakersfield group and all of the other amateurs.

Although I do most of my observing with a 16 inch dob, I decided to refurbish an 8 inch newt that I had made as a kid. To make the pier for my old edmund mount and drive, I purchased an aluminum tube from a metal company for $15.00. I notched-out the top of the tube with a hacksaw and dropped the mount into it and sealed it with two tubes of JB weld. The legs of the pier are available from Home Depot exactly as you see them for $9.00 apiece and are large "L" brackets used to attach book shelves to walls. I attached castors with levelers to each leg which are sold by Apogee( three for $16.00)The aluminum-pier tube is about 30 inches tall with a quarter inch wall thickness and weighs only eleven lbs. It's very rigid but my nine year-old daughter can push it with her fingertips. All of these materials are easily obtainable and may be considered by ATMers for future projects.

John,
I have the 8.6mm antares eyepiece and I am pleased with it's performance on DSOs and on Saturn. However, there may be quality control issues on the antares widefield line, as reported in posts in this forum. The problem appears to be with the coatings in that some have a green, apparantly ineffective coating while others have the more common blue coating which effectively reduces reflections and ghosting of images. I think the ultima line generally has a high level of quality control although the AFOV will be significantly less than the antares widefield design. If you do decide on the antares eyepiece, I would recommend contacting Jim at Scopestuff and ask him for the blue-coated units. Scopestuff is also an Astromart sponsor and includes shipping on their items. You may also consider the antares line of high quality plossls that apppear to be identical to the ultrascopic line and are sold by scopestuff and other dealers.

Steve,
Nice work on your dob. I've seen similar designs on a 6" dob from a semi-pro, and your work reminds me of his fine scopes. Enjoy it and thanks for sharing!

Ben,
I have one of these on an 8" newt that I am currently refurbishing. It was made by Novak and he will probably make one for you if you can contact him. I don't have his phone number at my fingertips but someone who reads this forum probably does. I purchased the sliding counterweights many years ago so I don't know his current pricing.