TAKAHASHI CCA-250 ASTROGRAPH
Takahashi
Corrected Cassegrain astrograph
250 mm
f/5
1250 mm
22.8 kg
TAKAHASHI CCA-250 ASTROGRAPH is backordered and will ship as soon as it is back in stock.
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The Takahashi CCA-250 is a Corrected-Cassegrain Astrograph designed for extreme deep sky imaging. The flat-field optical design combines a concave parabolic primary mirror and convex spherical secondary mirror, with an integrated corrector to provide a huge 88mm image circle, making it suitable for use with medium format sensors.
The CCA-250 has a native focal length of 1250mm and a fast focal ratio of f/5, making it the ideal instrument for galaxies and planetary nebulae. The motorized secondary mirror allows precise focusing with either the included hand controller or over ASCOM. Additionally, the tube features three cooling fans for the primary mirror with temperature sensors both inside and outside the carbon fibre tube.
In addition to the standard f/5 configuration, a 0.73x focal reducer is available (sold separately), reducing the focal length to 910mm and focal ratio to f/3.8 for wider views and faster exposure times. For large sensors, the 645 0.72x Super Reducer is available, reducing the focal length to 890mm and focal ratio to f/3.6 and providing an image circle of 60mm. A 1.5x focal extender is also available.
Spot diagram of Takahashi CCA-250 at prime focus.
Spot diagram of Takahashi CCA-250 with RD CR 0.73x focal reducer.
Spot diagram of Takahashi CCA-250 with 645 Super Reducer CA 0.72x focal reducer.
Spot diagram of Takahashi CCA-250 with EX CR 1.5x focal extender.
| Optical design | Modified Cassegrain |
|---|---|
| Mirror configuration |
Concave parabolic primary + convex spherical secondary + field corrector |
| Focuser |
Motorized secondary mirror focuser |
| Primary mirror diameter |
250 mm |
| Focal length at prime focus |
1250 mm |
| Focal ratio at prime focus |
F/5 |
| Backfocus distance at prime focus |
193.9 mm |
| Tube diameter | 306 mm |
| Tube length | 870 mm |
| Tube weight | 22.8 kg |
| SKU | TCK25000 |
| Prime focus focal length | 1250 mm |
|---|---|
| Prime focus focal ratio |
F/5 |
| Prime focus backfocus distance |
193.9 mm |
| Prime focus image circle | 88 mm |
| RD CR 0.73x reducer focal length |
910 mm |
|
RD CR 0.73x reducer focal ratio |
F/3.6 |
|
RD CR 0.73x reducer backfocus distance |
56.2 mm |
|
RD CR 0.73x reducer image circle |
38 mm |
| EX CR 1.5x extender focal length | 1880 mm |
| EX CR 1.5x extender focal ratio | F/7.5 |
| EX CR 1.5x extender backfocus distance | 117.5 mm |
| EX CR 1.5x extender image circle | 40 mm |
| 645 CA reducer focal length | 890 mm |
| 645 CA reducer focal ratio | F/3.6 |
| 645 CA reducer backfocus distance | 56.2 mm |
| 645 CA reducer image circle | 60 mm |
