Tasco 1575 User Manual
Page 73
4.5" DIA CONDENSER LENS, 6.5" FL
Crown glass condenser lens. Plano convex. 4.5 inches
diameter by 6.5 inches focal length. Unused.
Made in France.
L3381 $6.00
MTD B&L METROGON LENS, 6" FL
Metrogon lenses are a 4 element design with very
strong curved meniscus lens elements covering around a
90 degree field. They are used in aerial cameras for
very large format film for the preparation of topo-
graphic maps and for large format projection sys-
tems.The 6 inch focal length lens covers at least a 9" x
9" format at f/6.3. We know this lens has a 6 inch
focal length, but we do not know what the f number is and we don't have
the equipment to accurately determine the f ratio or the actual maximum
format for this lens. Our understanding is that as the center aperture is
made smaller (larger f number), the coverage format becomes larger. We
haven't yet taken one apart, so don't know if it will be easy or hard to
change the center stop. We did some testing and it looks like this one gives
about an 8" x 8" format as is. There is a small screw on top of the assembly
that loosens it and the barrel slides out. It's a compact 2" long by 2-1/16"
diameter.Metrogon lenses are the most extreme type of symmetrical con-
struction. Each side of the lens has two elements which provides correction
for color and spherical faults. We are told that the lenses are also com-
pletely free of distortion. Made by Bausch & Lomb. Coated optics. Great
condition. Front and rear elements are 45mm diameter. Focal length is
152mm. Barrel is 60mm diameter by 50mm long. Mounting 140mm long
by 85mm wide with 4 mounting holes. We don't find these very often
these days.
L3392 $28.50
GLASS ASPHERIC LENS, 50MM DIA X 30MM FL
Very strong aspheric curve on one side and plano on
the other. Diameter is 50mm and focal length from
the plano side is 30mm. Aspherics offer superior
aberration correction for light concentration that
would normally require several spherical elements.
Unused beauties.
L3467 $5.00
Lenses - Page 71
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