VdB152 nebula by Richard Galli
The CCA-250 (Corrected Cassegrain Astrograph) is a flat field telescope dedicated to deep sky astrophotography with an 88mm image circle. It allows the use of 3 different focal lengths by adding optional reducers and extenders. In addition to the standard F/5 focal ratio at the primary focus, it is possible to switch to F/3.6 using either one of the 2 reducers or to F/7.5 using one of the 2 extenders. The choice will depend on the desired image circle and the size of the camera sensor or photo housing used.
Motorised focusing, ASCOM compatible, is done by translating the secondary mirror. The fans responsible for cooling the primary mirror are managed by 3 temperature sensors distributed inside and outside the carbon tube. The telescope is delivered with a 7x50 finder and Losmandy type male and female dovetails.
With the CCA-250 telescope, Takahashi has created an extremely versatile astrograph with a top-of-the-range finish, irreproachable optical and mechanical quality and a magnificent design combining aluminium and carbon.
Specifications
Optical specifications | |
Optical design | Modified Cassegrain |
Combination | Concave parabolic primary mirror + convex spherical secondary mirror + corrector |
Diameter | 250 mm |
At prime focus | |
Focal length | 1250 mm |
Focal ratio | F/5 |
Image circle diameter | 88 mm |
Metal Back Distance | 193.9 mm |
With reducer RD CR0.73X | |
Focal length | 910 mm |
Focal ratio | F/3.6 |
Image circle diameter | 38 mm |
Metal Back Distance | 56.2 mm |
With reducer 645RD CA0.72X | |
Focal length | 890 mm |
Focal ratio | F/3.6 |
Image circle diameter | 60 mm |
Metal Back Distance | 56.2 mm |
With Extender EX CR1.5X | |
Focal length | 1880 mm |
Focal ratio | F/7.5 |
Image circle diameter | 40 mm |
Metal Back Distance | 117.5 mm |
Mechanical specifications | |
Length of the optical tube assembly | 870 mm |
Diameter of the optical tube assembly | 306 mm |
Weight | 22.8 kg |
Spot diagrams
System-charts of the Takahashi CCA-250 reflector | Download | |
System-charts of the Takahashi CCA-250 reflector with reducers | Download |
Instruction manual of the Takahashi CCA-250 reflector | Download |
ASCOM ActiveFocuser Driver made by Optique Unterlinden | Download | |
INDI ActiveFocuser Driver made by Optique Unterlinden | Download |
gallery