CDK400 System
Submitted by Chelsea Chin
PlaneWave CDK400 System
“The new imaging system in the new Pommier Observatory is a PlaneWave CDK400 system. A CDK 400 system consists of a CDK17 (17-inch) telescope mounted on an L500 mount.
The CDK17 is a fantastic telescope. It is fast, at f/6.8. The optics are truly superb. It produces a completely flat field with stunning clarity and pinpoint stars from corner to corner of my 35 mm CCD chip. It has a fused silica mirror and carbon fiber trusses that resist expansion and contraction and hold sharp focus throughout the night regardless of how much the ambient temperature changes. The CDK17 has many built-in fans that help it reach ambient temperature quickly and blow air across the primary mirror surface to remove the boundary layer of air that can blur images. I added several accessories to the CDK17, like the IRF90 rotator/focuser, the Electronic Focuser Accessory, and the Delta-T Heater dew control system. See those pages for details on them.
The L500 is an equally amazing mount. It is direct drive, so it has no gears and therefore no periodic error and no backlash. Once it builds a pointing model, it precisely centers targets on the CCD chip. It tracks flawlessly for long periods of time. Although I usually still auto-guide when there is a suitable guide star (see page on the IRF90), I can also now image subjects with no available guides star by just letting the L500 run all by itself and I still get perfectly round stars even with long sub-exposures. This enables me to image subjects I never could with my Compustar C14 due to lack of a suitable guide star. The L500 has through-the-mount cabling to prevent cable wrap.”
Check out Rod Pommier’s PlaneWave page, here!
Rod Pommier – Pommier Observatory | Portland, Oregon USA