PlaneWave CDK12.5 f/8 Optical Tube Assembly The CDK12.5 is a 318 mm Corrected Dall-Kirkham astrograph with a 2541 mm focal length. The design eliminates off-axis coma and astigmatism and gives a flat field across a 52 mm image circle, suiting large-format cameras for deep-sky imaging and research.
Manufacturer model: PlaneWave CDK12.5 f/8 OTA (125104Q) · Specifications checked against manufacturer data on 2026-11-03
The CDK12.5 is a 318 mm Corrected Dall-Kirkham astrograph with a 2541 mm focal length. The design eliminates off-axis coma and astigmatism and gives a flat field across a 52 mm image circle, suiting large-format cameras for deep-sky imaging and research.
Fused silica mirrors keep their figure and alignment as temperatures change, and the carbon fibre tube minimises focus shift. Cooling fans and boundary-layer fans speed thermal equilibrium, and primary and secondary mirror heater pads are ready for the Delta-T controller (sold separately). The OTA now includes PlaneWave's EFA box for automated focus, temperature monitoring and fan control through PWI4.
| Optical design | Corrected Dall-Kirkham |
|---|---|
| Aperture | 318 mm (12.5") |
| Focal length | 2541 mm |
| Focal ratio | f/8 |
| Central obstruction | 42% of primary diameter |
| Image circle | 52 mm |
| Optical performance | 2.8 µm RMS on-axis; 3.8 µm at 11 mm; 8.0 µm at 21 mm off-axis |
| Primary mirror | 318 mm optical / 330 mm outer, prolate ellipsoid, fused silica, enhanced aluminium 96% |
| Secondary mirror | 118 mm spherical, fused silica, enhanced aluminium 96% |
| Corrector lenses | 70 mm, broadband AR (<0.5% reflection, 400–700 nm) |
| Back focus from mounting surface | 265 mm (10.445") |
|---|---|
| Back focus from racked-in focuser | 183 mm (7.2") |
| OTA length | 787 mm (31") |
| Weight | 19 kg (42 lb) |
| Tube | Carbon fibre |
| Fan power | User-supplied 12 V DC, 2.1 mm barrel, centre positive (if no EFA) |
Standard CDK12.5 (aluminium coatings), not IRDK12.5. Losmandy D-style dovetail; fits Keller EZ saddle on L-350. Optional 0.66x reducer gives f/5.3, 30 mm field.
| Bf focuser (mm) | 183 |
|---|
Data sheet
PlaneWave CDK12.5 f/8 Optical Tube Assembly The CDK12.5 is a 318 mm Corrected Dall-Kirkham astrograph with a 2541 mm focal length. The design eliminates off-axis coma and astigmatism and gives a flat field across a 52 mm image circle, suiting large-format cameras for deep-sky imaging and research.
Manufacturer model: PlaneWave CDK12.5 f/8 OTA (125104Q) · Specifications checked against manufacturer data on 2026-11-03
