First experiments with a hydrogen-alpha filter

For those interested in imaging and image processing with DSLR, CCD, webcam or film.
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rwilkinson
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First experiments with a hydrogen-alpha filter

#1 Post by rwilkinson » Sat Nov 27, 2010 12:48 pm

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:
m42_halpha.jpg
40x 15-sec with h-alpha filter, using 50mm lens at f/4
m42_halpha.jpg (31.85 KiB) Viewed 3024 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:
m42_40x5.JPG
40x 5-sec using 50mm lens
m42_40x5.JPG (71.27 KiB) Viewed 3024 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:
m42_composite.JPG
composite of hydrogen-alpha image from 1004x with green and blue channels from SPC880LX colour image
m42_composite.JPG (65.56 KiB) Viewed 3024 times
OK so the images are a little noisy, but I'm definitely getting to grips with the processing steps! :)

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