From: "Steve Bryson" <stevebeam@yahoo.com>
Date: November 23, 2005 1:33:37 AM MST
To: Astro_IIDC@yahoogroups.com
Subject: Resolution vs. sensitivity
Hello everyone - I'm still working on choosing my next camera. Based on Alan's pictures
I'm not inclined to pay the higher prices of the PGR cameras, but I can't decide on which
imaging source camera. I understand that we might want to give sensitivity a priority, but
it's hard for me to let go of increased resolution. What do you think of following analysis
of the DMK 640x480 vs 1024x768 cameras?
DMK 21A/BF04 (640x480): pixel size 5.6 microns, pixel area 31.36
DMK 31A/BF03 (1024x768): pixel size 4.65 microns, pixel area 21.62
area of 640x480 pixel/area of 1024x768 pixel = 1.45
So each pixel of the 640x480 camera captures 1.45 times more light, so (assuming
everything's linear) the 1024x768 camera will require exposures about 45% longer for the
same image. This is a little less than half a stop. This impression I get in this newsgroup
is that these cameras have much higher gain than the fire-i, so a half-stop doesn't sound
to me like a big deal. Therefore I'm inclining towards the higher resolution. The
difference for the 640x480 flea is much larger, however.
Also (as Tim points out) the larger chip of the 1024x768 camera gives a larger field of
view which makes finding objects easier. This is a serious consideration with my
motorized dob mount, where simply changing the filter in the filter wheel can knock Mars
out of the field of view (very frustrating).
On the other hand I do not expect to ever get better resolution than Alan with his
640x480 camera.
Any thoughts would be appreciated
Steve