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 Post subject: First experiments with a hydrogen-alpha filter
PostPosted: Sat Nov 27, 2010 12:48 pm 
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Joined: Mon Oct 12, 2009 6:47 pm
Posts: 1263
Location: Bolton
The Society has recently bought a special filter for hydrogen-alpha imaging, which I have borrowed to do some tests.
But unlike the premium narrowband filters (which cost around £100), this one has a broader bandwidth (at half the price), which means that it rejects less stray light-pollution and moonlight, etc.

So last night I fitted this filter between my monochrome 1004x camera and a 50mm lens, and got this image of M42:
File comment: 40x 15-sec with h-alpha filter, using 50mm lens at f/4
m42_halpha.jpg [ 31.85 KiB | Viewed 2710 times ]

(the dark diagonal band is due to the shadow of a neighbour's 'phone line)

But now for the clever bit - I got the colour image which I took a couple of weeks ago with the SPC880LX webcam:
File comment: 40x 5-sec using 50mm lens
m42_40x5.JPG [ 71.27 KiB | Viewed 2710 times ]

and (after some fiddling in IRIS) re-scaled and aligned the monochrome image with the colour one, and then substituted it for the Red channel in the colour image, to form this composite:
File comment: composite of hydrogen-alpha image from 1004x with green and blue channels from SPC880LX colour image
m42_composite.JPG [ 65.56 KiB | Viewed 2710 times ]

OK so the images are a little noisy, but I'm definitely getting to grips with the processing steps! :)

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