The BRC-250 employs non-spherical surfaces for both the primary and secondary mirrors, and when they are
combined with two supplementary lenses, elimates spherical aberration, coma, and even astigmatism with a flat field. It produces a
focal ratio of f/5 with a 100mm 5º diameter image circle. It also produces an amazing 2 micron stellar image at the center of the
field.
The BRC-250 employs the Baker method to flatten the field over a wide field. However, because its primary and
secondary mirrors are hyperbolic, production was difficult. Today, Takahashi's unique technique in polishing non-spherical
surfaces has enabled the first mass production of Baker Ritchey-Chretiens.
The large 100mm diameter image makes the BRC-250 a versatile astrograph. The following formats cam be used:
35mm, 6x7, 6x9, and 4x5. The BRC-250 is temperature-compensated by using a space-age state-of-the-art carbon fiber tube which
assures precise focus that will not change with temperature fluctuations.
The extremely small stellar images makes the BRC-250 the perfect instrument for CCD imaging. The 100mm diameter
image circle will accomodate the largest commercially available CCD cameras
Takahashi 250mm f/5 Baker Ritchey-Chretien OTA Specifications:
- Optical System: Baker Ritchey-Cretien
- Aperture: 9.8" (250mm) Hyperbolic [Enhanced coatings]
- Corrector assembly: 2 elements [fully multi-coated]
- Focal Length: 50" (1268mm) [effective]
- Focal Ratio: F/5.0
- Light Grasp: 1276x
- Resolution: 0.47"
- Limit Mag: 13.8
- Image Circle: Ø100mm/ 5°
- Stellar Images: Less then 10 microns at the edge and 2 microns at the center
- Tube Diameter: Ø11" (280mm)
- Tube Length: 33.5" (850mm) [with dew shield]
- Weight: 34.3 lbs (15.6kg)
- Finder Scope: 7x50 6.3° w/ illuminator, 11x70 4.2° optional
- Main Tube Material: Carbon fiber
- Film Formats Usable: 35mm, 6x7, 6x9, and 4x5
