The camera is a Vcam CU-98 USB digital webcam.It has a reasonable resolution of 640x480 pixels with a maximum colour depth of 24 bits.
Mounting the camera onto the telescope was pure simplicity! The lens supplied with the webcam was simply unscrewed (the focus adjustment) and removed. A narrow close-up ring with a Pentax thread was epoxied onto the camera body, then the standard Meade T2 mount accessories took it from there.
Serendipitously, this setup also allows the use of standard
Pentax-thread lenses -
not just the telescope.
The photo at right shows just how tiny the active area of the camera is. It measures roughly 4x3 mm to yield its 640x480 pixel resolution.
A standard 35mm film frame measures 36x24mm, an area of 864mm².
The CCD in this camera has an active area of 864/12 = 1/72 the area of a 35mm frame.
Magnification (relative to 35mm) is roughly 9 times. Therefore, a 50mm "standard" lens is
equivalent to a 450mm telephoto.
The telescope used on this site has a focal length of 1450mm. Using it with the CCD is roughly equivalent to using a 13,050mm telephoto with a 35mm camera!
Yes... that would be a 13 metre telephoto!
Here we have the camera mounted on a standard 300mm Pentax-thread telephoto lens - equivalent to a 2,700mm lens on a 35mm camera.
For the moon, it works best stopped right down to f22.
View the first results here (20 day old moon - 30/9/1999).
Two and a half weeks later, the moon was in its first quarter. View it
here (7 day old moon - 17/10/1999).
