[ATMoB-discuss] Making a Dob vs buying a

[valleli at rcn.com]

Dave,
I am almost (ALMOST) ashamed to say that I would not consider making a Dob vs. buying one. I am a professional optician 
The engineering design and quality of manufacture in production by MEADE just cannot be matched by an amateur without investing enormous amounts of time crafting a similar instrument. 
Of course, there is no pride in accomplishment, no valor in paying out cash, no sense of self-worth coming from the making of your own "Eye into the Universe".

The same thing happened to me in 1973, when I deserted my T.N. ( telescope nut) credo and bought a Celestron 8-inch Schmidt-Cassegrain. At the time, I felt like a traitor to the club, but I was making optics for the Voyager Spacecraft at the time, and did not have the spare time to craft such an instrument. I have never regretted the purchase, and sometime hope to buy a 14-inch S-C. In the meantime, I can use the club's C-14 for CCD astronomy.

I highly recommend getting the 12-inch Lightbridge unless you have a tiny, 2 seater vehicle or no vehicle at all. Another consideration, the heaviest section, the mirror box, weighs 40 pounds. This could be a problem for some people. That silly little difference in aperture, from 10 to 12, makes a very significant increase in light-gathering power.  I plan to bring mine down to Skyscrapers RI convention on the 29th-30th and will try to get up to Westford on a Thurs. or Sat. night soon.( as the Moon moves into the morning sky).  

I must say, that I optimized the fast F/No. by buying a $300  ParaCorr coma corrector. The result, viewing M42, the Orion Nebula, is astounding with a 35mm TeleVue PanOptic EP. For now, I am sticking with the 24mm Plossl that is provided by Meade, although there is some residual astigmatism at the very edge of the field of view. I doubt you would notice it, unless called attention to it. It has a better Exit Pupil match for my ancient eyeballs.

A significant increase in counterweighting is needed with these glass "grenades" and I put some sheet lead in canvas bags along with some strong magnets to stick to the side down by the main mirror. I can do this because the main tubes are steel.

I believe the optics are polished in Taiwan and cannot find fault with the figuring. I assume they use a Null Test of some sort to enable rapid manufacturing. It would be nice to have Schott Zero-Dur mirrors but that would add greatly to the cost. It polishes much more slowly than ordinary crown glass.
Meade uses what looks like water-white plate.

There are a few minor problems, as Dennis DiCicco mentions in this month's review in S&T, but they are easily remedied.
I had to free-up the flotation mount for the primary. It had a tendency to bind, making it difficult to collimate the telescope.
I find I prefer to set the base on three paver blocks, rather than on the grass.  

If you are on a bare-bones budget, but have access to tools, plywood, time, and construction materials, and want the glory of having made an optical surface to an accuracy of a few millionths of an inch, then make it! 
Hope this helps
Paul