3Discover lens' replacement

[P3D Dr. George A. Themelis <fj834@xxxxxxxxxxxxxxxxxxxxx>]

Looney Gabiel to honorable Dr. George A. Themelis:

>Dr.T you once mentioned that the 3Discover optics were good. What is your
>opinion on how it stacks up to the Red Button or the Wollensak lenses?

3Discover lenses are good for inexpensive single element lenses but no
match to the fine Realist/Revere/Wollensak achromatic lenses.

>Secondly can the Wollensak lenses accomodate a 7 or 8p slides? If yes
>can this be used for improving the 3Discover.

Wollensak lenses are fine for 7p but stretching if for 8p but so are the
3Discover lenses.  At this point, and given the quality of the 3Discover
images, I don't think a better pair of lenses would make sense in this
viewer.  If you were to look at higher quality original images then we
could discuss it.

I have reports of successful installation of the Revere/Wollensak lenses
(BTW, these are old stock new lenses in their original mounts that I offer
for sale) in a number of viewers, including Kodaslide I and Star-D/Brumberger
viewers.  I have only installed Revere lenses in Realist viewers (to
replace damaged achromats or single element lenses in the white-button
Realist viewer) but will investigate other possiblities in the near future.

Specifications:  Size is 20 mm in dia. for both.  Focal length is 44 mm for
the Revere and 47 mm for the Wollensak lenses.

George


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