CCD vs Film? Lots of time vs no patience? Alright, this is your place to discuss all the astrophotography what's and what's not. You can discuss about techniques, accessories, cameras, whatever....just make sure you also post some nice photos here too!
A dark frame is an exposure equal in length as the light exposure and at the same temperature as the light exposure, so that the noise (mostly thermal) is recorded on the dark frame and will be used to subtract the noise from the light frame.
(I kaypoh and ans the question Embarassed )
No problem.
A dark frame is as what Meng Lee mention. A Light frame is the actual frame contains the image.
To take a dark frame, cover lens with the lens cover and cover the DSLR view finder with the view finder cover come with Canon DSLR. Now, with no light able to get into the DSLR sensor, took 10 to 15 frames at the same exposure time and ISO as your light (image) frames. Since you'll be on the mountain when taking your light frame where temperature will be greatly different from day, night and at the ground level, so you must took the dark frames straight or at least asap after your light frames. This is to make sure the dark frame will be taken at temperature around the same as your light frame, so the thermal (noise) map of your DSLR sensor can be subtract away from the light frame using the dark frames.
Have a nice day.
Yang Weixing "The universe is composed mainly of hydrogen and ignorance."
Once, when I happened to go mountain climbing, I simply placed my camera on a rock on the ground and shot 3x15sec shots Link. No tripod even! My anyhow-technique is to shoot as many images on as high an ISO setting for as long as possible (without star trailing) + dark frames. When you return you can process for noise and saturation.
I was at the French Alps last year and stayed at a cottage in Aravis. Surprisingly, my photos of the night skies were saturated with light pollution. I suspect they were from the ski resorts near Mont Blanc. Hope you have better luck!
[80% Steve, 20% Alfred] ------- Probability of Clear Skies = (Age of newest equipment in days) / [(Number of observers) * (Total Aperture of all telescopes present in mm)]
This is not a ski resort but staying at a Monastery. There will be periods of Silence and Lights Out. Hopefully, it will be dark and not be too cold...(there are no heaters there)
Dear all, just want to inform you that my two nights at La Sallete was clouded out on the first night and snowed on the second night. Had great fun in the snow but no pictures to show...
Cool... reminds me of the movie "The Name of the Rose"...
[80% Steve, 20% Alfred] ------- Probability of Clear Skies = (Age of newest equipment in days) / [(Number of observers) * (Total Aperture of all telescopes present in mm)]
"The universe is composed mainly of hydrogen and ignorance." 
