Quote:
Originally Posted by raymo
I have been astroimaging for over 50yrs; have made the switch to a
DSLR, but I think that it is a little late to go the next step to a CCCD
camera; however, I have a question that I haven't seen raised anywhere,
but that I would like an answer to.
I have bought " Imaging the Southern Sky' which gives all the
exposures that were used, using CCCD cameras that used the popular
KAF-8300 sensor. I understand that CCCDs are much more sensitive than
DSLRs. Can the ISO of a CCCD camera be changed, or are they fixed?
If they are fixed, does anyone know what the ISO is, so that I can
find out what ISO I would have to use with my DSLR to get
equivalent exposures[ always assuming that my DSLR can reach the
necessary ISO, that is]. Thanks in advance.
raymo
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The ISO is just a digital gain.
You could never expose a DSLR for as long as a CCD camera because
thermal noise will make the picture turn red.
On a Canon EOS 1000d I used an ISO of 800 normally.
ISO 1600 was no advantage because it amplified the noise.
You need to find out the "natural" unamplified ISO for your camera.
I think that was ISO 800 or maybe ISO 400 for the Canon EOS 1000d.
You'll find that in summer any longer than 2 to 3 minute exposures will have too much noise.
In winter you can go to 5 to 10 minute exposures at the most.
( if the air temperature is below 4 degrees C.)
Hope that helps?
cheers
Allan