|
Personal experience is
1. insulate around the corrector cell and most of the OTA barrel, this kills the thermal transfer via the walls of the tube which is the main problem as - without insulation - the ota barrel cools quickly while the central baffle does not.
2. do not insulate the back of the scope - this is where you do want to lose heat as the baffle cools by transferring heat to the back plate. This in turn cools the primary which is mounted on the baffle.
This is also borne out by my 10” APM mak which has a rear backplate with more holes than Swiss cheese - clearly intended to cool the back and the baffle effectively. This does work - on the nights I’ve had it out no tube current was visible at all by the time I’m set up and ready to observe (30 mins).
I think the posts on CN where people have totally encased SCTs probably has more to do with them being in a far colder environment (below zero) where keeping the scope warm is both necessary and a challenge.
3. I do use an insulated dewcap, made of 6mm coreflute.
4. If dewing is an issue either use a 12V hair dryer, or you could put a heater strap around the OTA inside the dew cap, just behind the corrector. To be honest I’ve never really felt the need on several maks, unlike SCTs.
|