Re: [ATM] More Dall Kirkham Secondary questions

[Mike Lockwood <melockwo@uiuc.edu>]

Rod,

Rod Brackenridge wrote:
> I think my secondary is finished.  I now have 4-8 lines arc lines across the
 > secondary when I place it on the reference.  There is no sign of 
any zones
 > other than a turned edge.  I am not worrying about the edge because 
it will
 > either be removed or covered.  The arc shaped lines bend by about a 
half a
 > fringe.
> Does this seem finished or should I persevere until I get perfectly
 > straight lines?

Ultimately, the quality of the scope will be dependent on both 
mirrors, primary and secondary.  I don't think you've mentioned what 
the figure on the primary looks like.

If the primary has an excellent figure and if you've successfully 
worked the secondary mirror this far, why not make it closer to 
perfect?  You should have an idea of what to do to continue perfecting 
the figure, so why not try it in short working sessions and creep up 
on the straight fringes?  For planetary observing, you will want to 
have the best optics you can make.

If the primary is coated and the scope is mostly assembled, you can 
try out the secondary (uncoated) and star test the whole telescope to 
verify its proper setup and the quality of the optics.  You should 
also have enough light to do a little planetary observing.

	Mike Lockwood

_______________________________________________
ATM mailing list http://www.atmlist.net/