Sabtu, 22 Juni 2013

Calling It Quits On The Telescope Rebuild

I was hoping to report victory on the telescope rebuild, but I'm just surrendering.

I cut 51 inches out of the middle of the tube:






And yes, it took 19 pounds of it.

But the cutting process wasn't pretty, and neither were the results:






Worst of all, when I was done I had the same problem with the lower cage that I had with the aluminum one -- too flexible.  I am beginning to think that this is a variant of the 50 pound bike theorem.  In case you aren't familiar with it, it was first explained by a friend (okay, a gal that I was convinced that I was madly infatuated with in 12th grade, before she went to MIT), based on the problems of bicycle retention in the Boston area:

1. A 20 pound bicycle is so valuable that it requires a 30 pound lock and chain to keep it from being stolen.

2. A 30 pound bicycle is in less demand, so it only requires a 20 pound lock and chain.

3. A 40 pound bicycle is barely worth anything, so a 10 pound lock and chain are sufficient.

4. A 50 pound bicycle doesn't require a lock and chain.  Who would steal it?

This reflects bicycle and lock technology of the 1970s; today the situation is probably somewhat different.  But I think the problem here is similar:

1. A big Newtonian reflector will either be heavy and stiff or light and floppy.

2. You can have a big reflector, but you either need a $6000 mount, or it is so hard to keep in collimation that it doesn't matter what mount you put on it.

Perhaps I should just make a Dobsonian mount, and give up on using this astrophotography.  Or perhaps I will just sell the parts to someone who has more energy to devote to building a Dobsonian.

UPDATE: CloudyNights has the ad here.




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