I live in an area with high humidity and temperatures regularly below 32 Fahrenheit(often low 20's and teens) this time of year. If I place the Mak in a soft telescope case made of nylon and polyester(padded or not)and sit it outdoors for a few hours would that be sufficient cooling time? Ive read that bubble wrap can help but am assuming(though not certain)there is no usefullness from the normal bubble wrap that telescopes are often shipped in. When people say reflective bubble wrap Im not certain what they mean. For people using frozen medical gel packs where on the scope do they apply them and how? The fan solution sounds involved. So do cat coolers but Im intrigued. If sitting the scope outside isnt sufficient by itself maybe Ill try to work with the other suggested methods as well or any others suggested. Maybe my Mak needs a vacation to a more hospitable environment and of course Id be compelled to come along.
I live in PA and have owned 8, 10 and 11” SCTs and a 7” Mak and currently own a Mewlon 210. They ALL needed aggressive cooling on most autumn, winter and spring nights.
There are 2 issues. The first problem is initial acclimation. The second problem is that on nights of falling temperatures, even after initial acclimation, if the primary can’t keep up with the falling temperatures heat plumes will reform and distort the light path.
With your sever temperature differences you might want to…
1. Leave the tube outside without any case or dew shield and let it cool. This can take hours and there is no guarantee that heat plumes will not reform if temperatures drop.
2. The cat coolers are fine for aiding with initial acclimation but on nights of falling temperatures you need to keep reinserting them to remove heat plumes. This, of course, interrupts observing or imaging.
3. With your sever conditions, a frozen gel pack (placed on the back plate) will probably have little impact. The gel packs do not come in direct contact with the primary so their cooling ability is marginalized.
4. People are having some success with insolation and there are a few threads about that solution. The idea is to keep the temperature inside of the tube stable (warm) so acclimation is not needed. You will have to wrap your scope before you take it out. And how long that insolation keeps the air in your tube stable can depend on many factors.
5. Fans on the back plate that blow cool outside air on primary is a solution used by many high-end Cassigran, Mewlon and Mak makers. The advantage is that fans will help with acclimation but they can be left running and can chase heat plume if temperatures fall. Of course, instillation can be a hurdle. The New Celestron Edge SCTs have fan ports and fan instillation is somewhat easy.
I have tried all the above except the insolation solution (which won’t work on my Mewlon) and personally like the fan solution the best. I believe Deep Space Products still does custom fan instillations. Even though my Mewlon 210 has an open tube, it still needed a cooling solution. I added 4 fans on the rear plate and they really help.
Try one of the easier solutions above first and if that works for you great. If not, just try another.