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 Post subject: Testing a monochrome webcam
PostPosted: Sat Sep 28, 2013 9:22 am 
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Joined: Mon Oct 12, 2009 6:47 pm
Posts: 1263
Location: Bolton
On Tuesday David passed on to me an old monochrome long-exposure webcam which he'd used years ago. This is a Philips TouCam fitted with a mono CCD and Steve Chambers' parallel-port control circuit - it needed a little repair (the three LX-control wires had pulled out out the plug), but I soon had it operating with an old WinXP laptop running wxAstroCapture.
Since then I've been waiting for an opportunity to test it with a Hydrogen-alpha filter - as the mono sensor has no Colour Filter Array in front of it, all its pixels receive the light, as opposed to just one quarter (the Red ones) in an RGB colour camera.

Last night we did have some gaps in the patchy hazy cloud, so I mounted the camera (in the black box) and filter behind a 50mm Pentax M42 lens (wrapped in the orange heater-tape) and bolted it onto my tracking platform:
monowebcam.jpg [ 202.53 KiB | Viewed 2611 times ]

Having set the focus and stopped down to f/4, I sighted Deneb and then moved "left a bit, down a bit" to try to frame the North American Nebula, and then set the program to take 20x 90-sec images. When I came back half an hour later, the cloud had thickened up, so I fitted the lens-cap and took a series of dark and bias-frames.
Then this morning I loaded the images into IRIS and soon had this result:
nan_ha_19x90.jpg [ 192.14 KiB | Viewed 2611 times ]
(even a slow old laptop can process these 640x480 pixel images really quickly!)

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