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fast achros are useless for double star work
I was messing about with a range of filters, and focal lengths, and thought I would see if I could get enough magnification to image a couple of doubles.
The seeing was appalling, stars roiling and boiling, so experimented with different exposures and ISOs. At the ridiculous focal length that these
images were obtained, I had to use ISO 6400.
102mm f/5 with 2x and 3x barlows stacked, and 6.4mm EP = 3,000mm f/length, and a stupid 468x mag.
First one is aCru, and the second is aCen.
raymo
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