Horsehead in Ha with OSC Camera

[DiscoDuck (Paul)]

Just trying some Ha imaging with my QHY8 on my RC8 - unfortunately OSC, so quite a low res with narrowband.

3 hours (6 x 30mins) on an RC8 + NEQ6 Pro. (Would've been longer but had to wait for it to clear the neighbours' tree - if I'd had my brain switched on, would've set up a few metres further up the lawn!! ).

Would drizzle help processing, given it is undersampled? (FWHM is halved to about 1.5 pixels or less, because of the Ha filter). According to the PI documentation, it seems to need (a) many images, and (b) dithering. I had neither, so didn't try it. Anyone done so?

Paul

[glend (Glen)]

Looks pretty good to me for a tripod setup on the lawn with those sub lengths. Is that cropped? My Canon DSLR poduces a much wider field of view through my RC08 on the Horsehead?

[RickS (Rick)]

Looks good for an OSC, Paul.

You really do need to dither to use the Drizzle algorithm. It's a fundamental part of how it works. However, you may find you have some natural dither happening anyway.

A bigger problem is only having 6 subs. That's almost certainly going to leave holes in the drizzle map where you don't have data. I think this will also be exacerbated because you're only sampling one in four pixels.

It doesn't do any harm to try and it would be an interesting experiment but don't get your hopes up!

Cheers,
Rick.

[DiscoDuck (Paul)]

Originally Posted by glend

Looks pretty good to me for a tripod setup on the lawn with those sub lengths. Is that cropped? My Canon DSLR poduces a much wider field of view through my RC08 on the Horsehead?

Thanks. No, it's not cropped at all. Should be the same field of view as any APS-C sensor camera, I believe. Full frame DSLRs would of course be larger.

Originally Posted by RickS

Looks good for an OSC, Paul.

You really do need to dither to use the Drizzle algorithm. It's a fundamental part of how it works. However, you may find you have some natural dither happening anyway.

A bigger problem is only having 6 subs. That's almost certainly going to leave holes in the drizzle map where you don't have data. I think this will also be exacerbated because you're only sampling one in four pixels.

It doesn't do any harm to try and it would be an interesting experiment but don't get your hopes up!

Cheers,
Rick.

Thanks Rick. Will give it a go in the future, when I have more subs and remember to dither. Re dithering, I've switched from a guidescope (where I was getting unintentional dithering with flexure) to an OAG and now no non-deliberate dithering (though better guiding ).

[RickS (Rick)]

Originally Posted by DiscoDuck

Thanks Rick. Will give it a go in the future, when I have more subs and remember to dither. Re dithering, I've switched from a guidescope (where I was getting unintentional dithering with flexure) to an OAG and now no non-deliberate dithering (though better guiding ).

Even if you don't Drizzle, dithering will really help remove fixed pattern noise so it is worth doing, Paul. Congrats on the successful improvement of your guiding!