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Fluorite
Calcium
fluorite (CaF2) is a naturally occurring crystal.
Its very low refractive index makes it the best of
materials to use in the manufacture of apochromatic
telescopes. Unfortunately, the natural crystal
contains many impurities and as a result make it
display some properties that make it less attractive
for use in telescopes. Now thanks to modern optics,
fluorite crystals are grown in an oven and the
product is a totally pure mono crystal structure
with all the good qualities of the lowest refractive
index, but with none of the problems associated with
the natural crystal. Now, this crystal can be hard
multi-coated for maximum light transmission and
durability.
As the
diagram shows, the band pass of fluorite of 1000 to
over 100.000 angstroms eclipses by many magnitudes
that of any optical glass. Additionally, the use of
multi-coatings further increases light
transmission over any ED glass. This makes any
fluorite objective brighter than any comparable
glass objective, not to mention the superior band
pass. These features make the fluorite objective the
premier instrument for photo/visual observations of
deep sky objects.
When the
fluorite instrument is taken out for an observing
session, 30 minutes should be set aside for
temperature equalization for maximum performance.
When making astrophotos, critical focus should be
checked after every photo to insure the best
possible results.
When
Takahashi first designed the fluorite apochromatic
refractor, they realized that the optimum design
placed the fluorite element in front. Coating
technology of the time did not permit this to be
done. Therefore, an alternate but excellent design
placed the element in the rear. Now, due to a
production and technological breakthrough, fluorite
can be hard multi-coated. The new FS series benefits
from this by placing the fluorite element in front
with low dispersion glass in the rear. The result is
the finest apochromat on the market today.
FS
series manual, 1994 |
FS SERIES
1994/4:
New
product FS-102 tube (102-820). FS series production
start.
1994/7:
New product FS-78 tube
announcement
(78-630).
1994/7:
New product FS-128N tube announcement (128-1040).
1994/9/17-30:
Astronomical guide October edition:
FS-102 & EM-200.
1995/7/22-23:
JTB Show'95, FS-78, FS-128.
1997/6/28-29: JTB Show'97,
ε-350 and FS-152, EM-10, EM-200USD
1997/7: Paint on the FS
series of the objective cell support-mechanism becomes blue.
1997/10:
New product FS-152 tube announcement
(152-1216).
1998/1: Astronomical guide
February edition: FS-152.
1998/2: New
product FS-128F tube announcement (128-1040), 4" focuser.
1998/6/27-28: JTB Show'98, BRC-250,
FS-128F.
1999/1: New product FS-60C
tube announcement (60-355).
1999/6:
The new product FSQ-106 tube announcement
(106-530). Modified Petzval desing, 4 lenses / 2 fluorite.
1999/6/26-27:
JTB Show'99, BRC-250, FSQ-106, Temma2, TG - SP, NJP.
1999/6: Monthly astronomical
July edition ' Telescope Review ': FS-60C.
1999/8: Astronomical guide
September edition: FSQ-106.
2000/6: New product FSQ-106N
(Kai) tube announcement (106-530), lens shade becomes sliding system.
2000/6/24-25: J.T.B
Show '00, BRC-250, FSQ-106Kai, FS-78C, FS-60C and FCL90 (SKY90),
EM-10/200 TemmaPC and TG-SP.
2000/7: New product FS-78C
tube announcement (78-630), compact lens shade.
2000/11:
New product Sky-90 (FCL-90) tube announcement
(90-500).
2001/1: Monthly astronomical
February edition test: Sky-90.
2001/2: Astronomical guide
March edition: Sky90.
2001/6/23-24: J.T.B Show
'01, BRC-250, FSQ-106kai, FS-78C and FS-60C.
2002/11: Astronomical guide
December edition: FSQ-106N (Kai).
2004/4: FS-102 minor change,
sliding type lense shade addition, new short version (NSV).
2005: FS series production
ended, available until stock is exhausted.
2008/4/1: FS-60C minor
change, FS-60CB with shorter tube (larger than FS-60CSV), new
dedicated reducer f4.2 available.
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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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