For those who want the
If you are looking for a truly professional
astrograph, the new Takahashi CCA-250 is your best choice!!
The CCA-250 is Takahashi’s first corrected Cassegrain
Astrograph. It was developed as a replacement for the
BRC-250 corrected Ritchey. This instrument was developed to
take advantage of the digital age and provide image circles
to cover large format imaging chips. The large ø88mm can
cover these large chip with a flat field filled with pin
This astrograph offers versatility. It is a tri-focal
instrument that can be used at its native f/5, at f/3.6 with
the small and large 645 reducer or at f/7.5. It will support
wide field to narrow field imaging.
The design of this instrument includes a carbon fiber tube
and a temperature compensated holder to maintain focus
during long exposures.
During long exposures temperatures can change and cause the
optics to change focus. The CCA-250 is equipped with three
computer controlled cooling fans that are operated by three
sensors: one on the primary, a second in the tube and a
third in the air to measure ambient temperature to help
prevent image shift working in concert with the carbon fiber
tube and temperature compensated holder. This cooling system
can also be operated manually.
The manual controls and computer interface are conveniently
located in a control box attached to the rear of the mirror
The control box also includes an input for the supplied 12v
power source and a USB input for computer control of the
The CCA-250 features a computer controlled secondary ASCOM
compliant Active Focus system. This enables computer control
by programs such as FocusMax or Maxim DL.
Takahashi’s original secondary focusing system was included
with the Mewlon-250 and 300 beginning in 1989, this latest
refinement uses a pulse motor which allows for the ASCOM
compliant focus programs to operate the Active Focus system.
The CCA-250 employs a corrected cassegrain optical system
with a large three element corrector to produce a flat ø88mm
circle with Stars 6 microns or less out to 50mm and 10
microns or less out to 88mm.
Balancing is very important to insure the best possible
tracking. The CCa is supplied with a heavy duty 18” long
dove tail which is an integral part of the tube assembly and
a wide 15” bridge plate to allow attaching a variety of
guide scope if needed. An extra heavy duty saddle plate is
also supplied to couple with Takahashi mounts.
The CCA-250 is a very versatile optical system. It can be
used at three different focal lengths 910mm [f/3.6] with the
small or large 645 Reducer QE which produces a 60mm flat
circle to support large format cameras, 1250mm [ f/5] prime
focus and 1880mm [f/7.5] with Extender CR 1.5x.
Optical and Mechanical
Quality always comes first. Without these qualities, a large
aperture is pointless!
Outstanding Features of the TAKAHASHI CCA-250P:
Optical performance: 2 microns RMS-spot radius on
Image circle: 88mm diameter (60% illuminated)
Image angular: 4 degrees diameter
Back focus/metal back: 155.4mm -193.9mm with the Camera Angle Adjuster
Computer-controlled Electric Focuser
Rear assembly contains a large camera rotator and
can utilize an electric rotator for remote operation.
The Takahashi CCA-250P Tri-Focal Astrograph operates
at three different focal lengths: f/5, f/3.9 (with 6345
Flattener) and f/8.
Design incorporates a carbon fiber tube to allow for
light weight and stable focus.
Includes integrated D series compatible dovetail for