ATM Transforming junkscopes to guidescopes

["Hugh J. Masterson" <mastersonh@dcu.ie>]

Hi,

Just a note on the transformation of a 60 mm refracting junkscope 
into a useful guide-scope. which I performed, and which might be 
helpful to others. My particular junkscope possessed a 60 mm air 
spaced objective with just one of the four glass surfaces coated. 
The resulting glare from multiple reflections had to be eliminated by 
baffling down the scope to an effective aperture of less than 50 mm 
at a guess. I dispensed with all the useless zoom optics and 
cheap eyepiece and used plumbing components to fit a standard 
1.25 inch 25 mm Plossl. Most importantly I got rid of  the air space 
in the objective by dispensing UV curing optical adhesive (Norland 
optical adhesive, available from Edmund Scientific) between the 
glasses and curing (a UV strip light of the type use in Discos that 
make your shirt go white is perfectly adequate).


Because of the index matching, the glare is effectively gone and so 
are the baffles. I now have a fairly decent guidescope with 60 mm 
clear aperture which is perfectly usable for my 8.75 inch Dob and 
gives stisfactory imaging at lower magnifications.

Hope this is of use to someone,


Hugh Masterson