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Fluorite refracting
telescopes
Attention has been generally directed toward
fluorite as an optical material for its unique
optical characteristics since 1886 when Abbe used
fluorite
CaF2
for its application in apochromatic
lenses for microscopes. Following the introduction
of the camera lens in the 1960’s, Takahashi
Seisakusho Ltd. company
started the development of fluorite objective lenses
in 1970 for astronomical telescopes for the first
time, and in 1977, the 90mm fluorite refracting
telescope was announced and received domestic and
foreign praise as the premier refracting telescope.
From 1981, beginning with FC-100, FC-65, FC-76, and
then in 1982, FC50, FC-125 etc., small and medium aperture
machine types announced the entire F8 series, and
the FCT and FS series which improve capabilities to
a greater extent were further developed while the
superior optical capabilities of fluorite were
pursued to the extreme, and finally, a product with
good operation capabilities as a short focus
telescope with no chromatic aberration was realized.
Also, reducer development was carried out that could
not be actualized in the former refraction telescope
simultaneously with the successful mass production
and sale of an epoch-making telescope which
introduced the new concept of a high quality optical
system where visual observation and a combined use
of photographic set-up is possible.
Unofficial translation from Takahashi Seisakusho
Ltd. product catalog document (1994) |
FCT
SERIES
1984/7/20-21:
FCT-150 preproduction model at '84 telescope & binoculars
spreading/displaying' exhibition.
1985/3:
New product FCT-76 tube announcement (76-487).
1985/7:
New product FCT-150 tube announcement (150-1050).
1986/1:
New product FCT-100 tube announcement (100-640).
1986/7:
New product FCT-65 tube announcement (65-320).
1986/7/25-26:
FCT-125 preproduction model at '86 telescope & binoculars
spreading/displaying' exhibition.
1986/10:
Lenses becomes multiple coat on the FC and FCT series except
fluorite lens.
1986/12:
Monthly astronomical January edition, 'FCT-65' test report.
1987/3:
New product FCT-125 tube announcement (125-705).
1987/6:
Astronomical guide 'New Face Test Report ', FCT-76.
1987/9:
Astronomical guide October edition, ' New Face Test Report ',
EM-10 & FCT-100.
1987/11/22-23:
'large only city' FCT-200 with EM-2000 equatorial mount at Yorii
factory and the Nagoya showroom.
1987/12:
The FCT-76 is modified to rack and pinion focuser system.
1988/1:
Dark green paint becomes on light green paint on telescopes.
1988/2:
Monthly astronomical March edition, EM-10 & FCT-100 test report.
1989/12:
Astronomical guide January edition, ' New Face Test Report ',
FC-125, FCT-125.
1990/January to April:
Fluorite gemstone crystal sale available at FC or FCT tube
purchases.
1991/10:
New product FCT-200 tube announcement (200-2000).
1992/6/25:
FC and FCT series, also fluorite element becomes multiple coat.
2000/2:
New product FCT-250 tube announcement (250-2500).
2002/11:
New product FET-200 tube (Triplet Fluorite ED).
2006/2:
New product FET-300 tube announcement (300-2400).
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Fluorite telescopes (1979-2008) by
Takahashi Seisakusho Ltd. becomes on
ED telescopes (2003- ) in order to contribute
in the diminution of the contamination generated
during the process of manufacture of fluorite
lenses. |
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