P3D Re: Wollensak vs Revere (viewer lenses)

["John Goodman" <jgood@xxxxxxxx>]

On 26 Nov 99, JVapor7@xxxxxxx wrote:

> I am having Dr T replace the lenses in my red-button viewer.  I am thinking 
> of putting in the Wollensak lenses as they have I believe a shorter focal 
> length and perhaps I can use the viewer without glasses while mounting.  Can 
> anyone offer pro and con testimony to Wollensak vs Revere replacement lenses? 

Dr. T could give you all these details and more.  :-)
I put Wollensak lenses in a red-button that had clouded 
lenses and there were some difficulties. First, I had to 
make washers so the lens glass would be snug in the 
mounts since the thickness is less than the original Realist 
ones (diameters are the same). The W. lenses are also a 
bit longer in focal length, so I found that the focusing range 
was just a tad cramped (i.e. I wanted to rack the lenses 
out just a bit more than was possible, to have a 
comfortable range). I reversed the focusing racks in the 
viewer which gave me additional focusing play, but at the 
expense of the feel at the very end of the range, where the 
bump stops normally are. Not ideal, however this might 
depend on how your eyes focus. The 47 mm W. focal 
length is supposed to give a bit more coverage for wider 
than 5p viewing, but the original Realist lenses may offer 
easier viewing in the corners despite this. Although I've not 
done it, it's supposed to be not too difficult to re-cement 
achromats that have a degraded joint, if you have the right 
solvent to split the elements and the proper cement to join 
them together again after cleaning or polishing.

JG