The advantages of this camera would be the low price, large imaging device (2475x1650,
4.1megapixel), large field of view, large pixel size (11.5micron), one shot color, a shutter to keep the imaging device
clean and the fact that it uses a CCD rather than a CMOS imaging device. The CCD sensor has a average Q.E. of 40-50%. Most
CMOS sensors have Q.E.'s below 30% (see image below).
Dis-advantages would be 12-bit Bayer color imaging (vs. 16bit), non-removable low pass I.R. filter
which causes red absorption at the Sodium line (light pollution), Firewire IEEE 1394 PC connection (vs. USB), amplifier noise
and no CCD cooling.
Camera Modifications:
01/09/2008. Amplifier noise in this camera is terrible (see purple haze in the images below). We are
now in the process of modifying the camera to disable the amplifier during long exposures.
Removal of the IR filter will be done and replaced with a Clear Glass Filter. This will
move the red absorption peak to 625nm, away from the Sodium line (light pollution) and towards H-alpha (see image below
and above).
Cooling will be attempted sometime in the future.
Telescope/Image scale:
The camera is used with a Meade 16" LX200GPS with a 0.63 focal reducer which yields a 2,530mm focal
length. This is a very long focal length, large pixels are a must. Since the camera has 11.5 micron pixels, it still yields
a image scale of 0.94 arcsec/pix and 1.88 arcsec/pix binned 2x2. The field of view is 25.9 x 38.8 arcmins (see image
at below).
The software used is Diffraction Limited's MaxDSLR. This software is expensive and complicated but does
the job.
M42 Orion Nebula; 60sec. exposure, ISO200, noise reduction-2 enabled (NR2), saved as CR2, no processing.
As you can see there is a significant amount of amplifier glow in the corners.
M42 Orion Nebula; 60sec. exposure, ISO800, noise reduction-2 enabled (NR2), saved as CR2, no processing.
As you can see there is a significant amount of amplifier glow in the corners.
M42 Orion Nebula; 60sec. exposure, ISO1600, noise reduction-2 enabled (NR2), saved as CR2, no processing.
As you can see there is a significant amount of amplifier glow in the corners.
The noise reduction seems to do a better job at higher ISO's in removing the vertical and horizontal
artifacts.
M42 Orion Nebula; 60sec. exposure, ISO200, noise reduction-2 enabled (NR2), saved as CR2, cropped and
processed in Photoshop CS2.
01/09/2008. Amplifier noise in this camera is terrible. We are now in the process of modifying the camera
to disable the amplifier during long exposures.
All images on this site are subject to copyright and must not be reproduced without permission
from the Cedar Glen Observatory
|
