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Old 07-09-2020, 08:57 AM
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Don Pensack
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Don Pensack is offline
Join Date: Aug 2006
Location: Los Angeles
Posts: 426
Originally Posted by MortonH View Post
Nice job but the wisdom these days is insulation not cooling.
But with an SCT Cooler on my 8" SCT, I got perfect star images at the start of the night after 45 minutes with the SCT Cooler in the scope during twilight.
When I didn't use the cooler, it was 3-4 hours before I stopped seeing thermal issues in the scope.
The reason was because I stored my scope at home in a closet that was usually around 20C, but my observing site was typically 10C at sunset and 0C about an hour and a half later and maybe -5 to -8C by dawn. The scope was always WAY too warm compared with the air.
The SCT cooler got the interior of the tube down to the ambient temperature quickly. In the middle of the night, I'd take a break and put it back in for 15-20 minutes while I was eating or using someone else's scope.
It worked like a charm and gave excellent star images when seeing allowed.
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