I Keep Learning

["Thomas Droege" <tdroege2@earthlink.net>]

TOM2 and TOM3 have been off the last several days.  A small sprinkle came
up and the dome closed.  T2 and T3 mostly point up, so any water landing on
the lens works it's way into the tube and soon I have small cloud chambers.
The flocked paper makes this worse since it soaks up the moisture and keeps
the cloud going.

Saturday I opened up the TOM2 lenses and dried them out.  To solve the
problem for the future I used some of the 3M heat shrinkable film that is
used to make temporary storm windows.  This made a very uniform and
transparent shield for the lens.  

I hear some of you giggling already.

When I ran the telescope, the results were awful.  Where usually I can see
a 5 mil focus effect, 25 mils made little difference.  The stars were just
big fuzzy blobs with a FWHM of 7 pixels or so.  

When the film was removed, the focus went back to normal.  The film really
looks uniform and clear.  My brother suggested that the stretching
operation might cause the film to become polarized.  Anyone with
experience, knowledge or suggestions?

The next plan is to just seal the end of the lens with a bead of RTV. 
Hopefully I will be able to get this off to take the lens apart when it is
next needed.  Since this is the third or so time that this has happened, I
need to do something.  

Tom Droege