THE 1004x JG CCD ASTRO CAMERA
NOTE: This section is mainly of historical interest as it date back to the pioneering days of QCUIAG in 2002. It is largely because of the pioneers active on QCUIAG around this time that we have the wide choice of inexpensive astro cameras available today. Building and using this camera taught me a lot about camera design and astro imaging techniques.
This CCD camera is based on a highly sensitive low cost CCTV camera board from RF concepts.
To capture faint deep sky astronomical objects long exposures are needed, so I modified the camera according to Jon Grove's innovative hardware design.
The output is captured using a Hauppauge WinTV capture card and 200Mhz Pentium PC. Jon Grove's iCatch software selects and saves the correct long exposure frames.
STOP PRESS:- I have now built an adaptor to the USB version as described on Jon Groves site and normally use the Hauppauge USB live capture device with a 400MHz Pentium II laptop. (See link below for more details)
Many thanks to Job Grove and Steve Chambers for their great work!
Peltier Cooler
As exposures become longer, thermal noise produces an increasing number of unwanted bright pixels in the image. This is made worse by the heat generated by the camera itself. To reduce the effect, I added a Peltier cooler to the camera. This cools the CCD chip through the metal lens housing, which gets well below zero deg C during operation.
Eliminating bright star shadows
To enhance the faint objects in the images, the image contrast has to be increased beyond what is necesary in normal use. This highlights a weakness of the camera, namely the generation of dark shadows to the right of bright stars. Following conversations with Jon Grove, we have been able to significantly reduce their intensity without significantly degrading the image sharpness by adding a 3nF capacitor across the camera video output.
Colour Imaging
Although the camera is monochrome, full colour images can be produced by combining unfiltered and red green and blue filtered images in software
Further Modifications 18th October 2003
I have modified the camera to use s-video capture card input and increased the gain 4-5x using Jon Grove's maximum agc gain increase modification
Links
Pictures of the completed camera
Pictures of the Peltier cooler
Test results of thermal noise reduction
Colour imaging equipment and techniques
Modification to allow use with a USB laptop
S-video and increased gain modifications
|
|