Posts Made By: Walter Hamler

I think you mean the altitude bearing?? If you cut the Teflon into 4 equal pieces, 1 x 1.5x 3/8 thick, then a countersunk woodscrew in the middle of each one should pull it into good contact with the wood radius so the bearing will essentially contact the teflon somewhere near the center of each pad (that's why you countersink the screws). May have to do some judicious trimming and shimming to make it fit.

Walt

About a year ago I was in the local Photo/Hobby store that carries a nice array of Celestron scopes and some of the smaller Meade GoTo's. A young teen was asking about trading in his 4" ETX in on something better, but neither he nor the salesperson really knew what "better" was. A lady was standing aside and I simply asked if she was the lad's mother. She acknowledged so I gave her my business card and told her to please call me before making any decision. I explained that I was an advanced amateur astronomer and telescope builder. Fortunately she did call, and 8 weeks later we had Andy deep into building a 10" f/7 newt which is now long finished and the whole family very proud of and enjoy emmensly!!
If you have the knowledge, don't ever hesitate to step in with a useful suggestion.

Walt

I found a copier lens a few years ago that was about 4" and made a rft from it. The people in the local astronomy club were so wowed with it that a bunch of them did the same thing. I still remember it giving the most stunning view of M-31/32 I have ever seen!

Walt

If it is Phenolic it would make a great tube. A few coats of polyurethane inside and out, a little sanding and then a final coat of paint. If you are careful with mirror cell and spider selection and placement, 48" would "just" make it, but you may have to add a "lens hood" at the front to prevent stray light glare and cut down on dewing. That could be made from just about anything.

Walt

At a recent star party a fellow member had both his scopes setup, a 15" Obsession f/4.5 and a Astro Physics 130 f/5. We put both scopes on Jupiter and got the image sizes close to the same size with Pentax XL eyepieces. The 15" was the best every time at full aperature. The seeing was good but definitely not what it can be here in FL. Even my 8" f/6 newt gave images that were sharper albeit a tiny bit less contrast than the AP. There is an old saying among drag racers, " There is only one thing better than cubic inches - and that's more of them!!" Aperature always rules if the quality of the optics will allow.

Walt

Definitely take it! Skies there can be as good as here in central Fl and down south. Would be terrible to get down there without it and then wish you did!!
Walt

I bought a set of the Orion "cheapie" eyepieces, not the Plossl's (although one or two are actually 4 element plossl's, the others are 3 element Kellners) I was very favorably impressed with them in an f/12 scope and on an f/6 dob. When bought on sale and in sets of three they cost less than 20.00 each.

Walt

Go to http://www.mcmaster.com/ Scroll to the bottom under Fabrics. Click on Velvet. It is available with or without adhesive backing. GET THE NON adhesive and use Titebond II to glue in the tube. Looks like a Black Hole when finished!!

Walt

What you have obviously is an old aerial camera lens probably used in high altitude a/c such as a U-2, TR-1, or maybe even an SR-71. They were designed for very high altitude (hence fixed focus) on either 5x5 or 9x9 format film (inches). Most of those type lenses were designed for use with deep orange or red filters for maximum haze penetration with B&W films. However some in later years were designed to be used with color trans films specially designed for aerial photography. When I was in the Navy we used these type cameras in the RA-5 for "standoff" photography because of their extremely high resolution. As a matter of fact most of the specialized optics used then were classified but no longer(at least the generation you have). I would imagine that it would make a fine "wide field" camera using as large a format as you can get, most definitely up to 4x5 or 5x7, but even 120 would be useful as you would be in the "sweet spot" all the time. As for visual use, I would imagine an ota made from the optical tube you have would be fairly heavy so a pretty massive mount would be of absolute necessity! Good luck!

Walt

Check these folks out. I believe they sell the components seperatly http://www.astrosystems.biz/

Walt