Thanks Marc. I will try some warmers. The nikkor ed is a great lense and the focus locks with an adjustable click knob if you don't handle it. But I could add tape to save the bumps.
I have made a Bahtinov with fishing line like a tennis racket ( after a East European design) which works on the lense on bright stars at full live zoom Problem is focus changes over time but the warming and the taping might help. Once I have found the target I don't want to move to check.
And then a radio so I don't miss the World Cup out in the dark. Close match this morning.
Quote:
Originally Posted by multiweb
Looks very good for a lens shot, no chromatic aberration. With lenses I tend to focus by the numbers. As you've pointed out the aperture is too small to use a bahtinov mask effectively. Using Nebulosity and picking a bright star you can check the numbers and focus accurately this way provided the seeing is not too bad. Then I tape the barrel of the lens with electrical tape across so it locks it in focus, then stick a pack of hotties on top and bottom then finish off wrapping it with a sock. That usually gives me 8h to 10h of passive heating and that's good enough to last the night.
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