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Martin,
Very generous to share your knowledge here. Yes I do use cal frames and only recently have taken the approach of using darks with the dust cover on the scope instead of the camera cap. I have never seen so much noise in the subs I’ve recently taken and I can only put it down to the fact that I am now autoguiding(it’s been a long time coming). In the past my slightly off polar alignment was most likely assisting the sub frames due to the drift acting as dithering! I will no doubt take on board the concept and see if I can change the settings in PHD to accomodate this.
I’m glad you have spelt out the science behind ISO settings vs noise.
I have only ever managed 30-40sec subs prior to autoguiding and even then stars weren’t the best shape. I’ve now been able to hit 90sec with PHD using this heavy OTA and this has changed the game.
With 800ISO using the us/ir cut at 90sec I’m going to have to see how much sky glow washes out the subs. It’s takes in a lot of light my scope! My reason for installing guiding on the system was primarily to entertain the idea of Ha imaging as it needs longer exposures. But even now I have come to learn that DSLR imaging with Ha filter isn’t ideal due to the Bayer matrix anyway.
One thing leads to another…I’ll keep using the 60D for as long as I can before I decide on upgrading to CCD cooled cam.
Cheers mate.
A
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