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Takahashi CCA-250 Astrograph

Stock code TCK25010



Introduced in 1998, the BRC-250 astrograph adopted a totally original optical design, based on Baker-Ritchey-Chrétien, perfectly designed for the imagery at that time. Following the recent evolution of CCD cameras offering larger sensors, Takahashi decided to modify its optical design. To work out this new CCA-250, successor of the BRC-250, the optician engineer Mr Mori Hitoshi opted for a Cassegrain base to lead to this new instrument perfectly adapted for the various objects of the deep sky.

CCA-250 (CCA stands for Corrected Cassegrain Astrograph) offers 3 kinds of focal lengths by the addition of optional reducers and extenders. From F/5 standard focal ratio at primary focus, it is possible to go to F/3.6 by using one of the 2 reducers or to go to F/7.5 by using one of the 2 extenders available. The choice of the model of reducer and extender will depend on the image circle needed, but also according of the size of the sensor of the camera used.

Finally Takahashi carried out a very multi-purpose astrograph offering a extremely high standard product bringing a great optical quality as well as irreproachable mechanics on top of which is added a splendid design associating aluminum and carbon.

Technical Specs

Optical designModified Cassegrain
Diameter of the primary mirror260mm (Useful aperture : 250mm)
Features of the primary mirror260mm, Pyrex parabolical mirror, F/2.75
Features of the secondary mirror125mm diameter, Pyrex spherical mirror
Mirror coatingsProtected high reflectivity
Corrector3 lenses, 80mm diameter
Lens coatingsFully multicoated
Back focus (BFL)193.9mm (without CAA)
155.4mm (with CAA)
Resolving power0.47"
Limiting magnitude (visual)14.1
Standard assembly
Focal length1247mm
F/D ratioF/5
Image circle88mm, champ 4° (60% without vignetting)
Resolution2µ RMS (optical axis)
3µ RMS (10mm)
3µ RMS (20mm)
4µ RMS (30mm)
6µ RMS (40mm)