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.
| Characteristic | Takahashi CCA-250 reflector |
| 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 RD CR0.73X focal reducer | |
| Focal length | 910 mm |
| Focal ratio | F/3.6 |
| Image circle diameter | 38 mm |
| Metal Back Distance | 56.2 mm |
| With 645RD CA0.72X focal reducer | |
| Focal length | 890 mm |
| Focal ratio | F/3.6 |
| Image circle diameter | 60 mm |
| Metal Back Distance | 56.2 mm |
| With EX CR1.5X Extender | |
| Focal length | 1880 mm |
| Focal ratio | F/D 7,5 |
| Image circle diameter | 40 mm |
| Metal Back Distance | 117.5 mm |
| Characteristic | Takahashi CCA-250 reflector |
| Length of the optical tube assembly | 870 mm |
| Diameter of the optical tube assembly | 80 mm |
| Weight | 1.4 kg |
| Focuser type | Motorized motion of the secondary mirror |
Spot-diagram of the Takahashi CCA-250 reflector at prime focus
Spot-diagram of the Takahashi CCA-250 reflector with reducer RD CR0.73X
Spot-diagram of the Takahashi CCA-250 reflector with reducer 645RD CA0.72X
Spot-diagram of the Takahashi CCA-250 reflector with extender EX CR1.5X
| Main system-chart of the Takahashi CCA-250 reflector | Télécharger |
| System-chart of the Takahashi CCA-250 reflector with reducers | Télécharger |
| Instruction manual of the Takahashi CCA-250 reflector | Télécharger |
gallery
VdB152 nebula by Richard Galli
LBN740 and VdB13/16 by Richard Galli
Iris nebula by Richard Galli
