The Cats Paw in H alpha with an ED 80 and Canon 300D

[seeker372011 (Narayan)]

With a first quarter moon around last night, the only way to take advantage of a clear night was to image in H alpha (unless you do a Scott and wake up (shudder) at some ungodly hour in the am )

Details:

Camera: Canon 300D (modified)
Filter: Astronomik 13 nm H Alpha
Mount: CG5-autoguided
Exposure: 12 x 10 minute subs-two hours total
ISO :1600
Processing: Deep Sky Stacker/Photoshop

in the end found I couldn't eliminate the noise without losing more detail so the image is probably a bit noiser than I would have liked it to be-the penalty for shooting with a non-cooled DSLR at high gain I suppose.

The other penalty for shooting with a DSLR is of course only 1 in every 4 pixels is actually usable data-since I discard the blue and green channels as noise.

Still you can only do what you can with the gear you've got I suppose, though any suggestions to improve processing or reduce noise would be muchly appreciated

larger version available at:

http://www.flickr.com/photo_zoom.gne...4260671&size=o

thanks for looking and any comments and suggestions most welcome
narayan

[Ric]

Very nice Narayan, I really love these Ha images you can really see a cats paw in that one.

you sure your cat didn't tread on your lens

Cheers

[tornado33]

Great image.
yes noise in HA images is unavoidable as you say not every pixel is used in narrownabd imaging, only red ones. I do wish Canon would make a monochrome chip (should be cheaper as no bayer filter and no colour processing needed)
Scott

[Bassnut (Fred)]

Nice work narayan , NB is hard with a DSLR.

Number of pixel isnt everything. My cooled CCD is only 1.6mp !. Even using a quarter of yours is still more than I have. Seeing and image scale often renders pixel count mute.

You can increase resolution somewhat by upsampling (increasing image size) in PS before processing. Processing then smooths out pixelation.

The artifacts near the stars can be avoided by selecting them, ("colour selecting" in PS, modify expand and feather), invert selection and then everything but the stars will be processed until you deselect.

Of course, you can also use the selection (un inverted) to seperately process the stars (eg, make smaller).

Cheers
Fred

[Dr Nick (Nick)]

Nice picture!