[mental4astro (Alexander)]

To quote Dirty Harry, "A man's gotta know his limitations".

A dewshield is a quick and easy starting point that will help. The dewshield can also double as an insulating wrap for your Mak. The old school way of treating a Mak and SCT was to wait for the OTA to cool after setting up. The issue being that a heat plume would develop inside the still warm scope which would disrupt the quality of the image at high magnification. The problem with this is the wait time. Depending on the size and type of scope you have, this can take anywhere between an hour to three or even longer.

But there is a way to avoid needing a wait period and start ripping high magnification straight away from setting up, by insulating the OTA.

As the scope cools, the metal tube cools quickly and much sooner than the warm air, primary and baffle tube inside the OTA, so a heat differential is created between these and hence a heat plume is generated. But if the OTA is insulated then the tube won't cool quickly, no heat differential is created and so no heat plume, meaning you can use the scope straight away.

I have been insulating my SCT's and Maks for several years now. I have used old yoga mats for these and right now I have made insulating wraps for my Maks using Coreflute, and even a car sunshade. Other people have used other insulating materials for this. The way that you design this wrap will allow you to make it dual purpose of wrap and dewshield.

Below are pics of the wraps I've made, for an old orange tube SCT (yoga mat), 9" and 127mm Maks (Coreflute) and a friend's 6" Mak (car windscreen sunshade). A dewshield for this last scope is a separate item rather than being all in one.

Alex.