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Moon in H-alpha

opticalpath

By opticalpath
in Imaging - Lunar

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opticalpath

opticalpath

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Something I took a while ago ..... in the days when there was an occasional clear sky.

Just a curiosity really. I'm not set up for lunar/ planetary imaging and this was taken with my deep-sky imaging rig: QSI 583 camera and MN190 scope (1000mm f.l.)

45 x 0.04 sec through an H-alpha filter. Processed in AS!2, Registax 6 and Photoshop.

http://universalcons...com/Moon-45.jpg

Adrian

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opticalpath

opticalpath

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That is absolutely gorgeous!

1.8 seconds total exposure...hope you were guiding :p

Did the hydrogen alpha combat the effect of seeing?

Dan

Yes, for once no guiding issues ..... I could get used to this!

I'm sure the extreme red wavelength of the filter helped in the usual way - reduced atmospheric scattering at longer wavelengths. I'm not sure if the narrow passband helps too, or not.

I had little choice though; my astro camera shutter won't go faster than 0.03 sec and I was shooting at f/5.3, so I had to use a very dark filter. Definitely not used to a *surplus* of light!

Adrian

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opticalpath

opticalpath

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.... I'm sure the Ha filter helped a lot to bring this pinging sharpness.....

Olly

I'm sure that's right, Olly; red or even IR filters often give the sharpest images. What I'm not sure about is if the narrow pass band of the Ha filter contributes to the sharpness, or if it's just the long wavelength effect. I don't get any discernible chromatic aberration with the MN190 so NB would not particularly benefit that. Might be interesting to compare a OIII image.

I had not tried AS!2 before, for multi-point alignment and stacking. I must say I'm impressed with it.

Adrian

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  • 2 weeks later...
SnakeyJ

SnakeyJ

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Lovely image and a quite a radical departure from deep sky imaging. Fantastic detail from just 45 frames/exposures and just over 3MP, I assume this is a full disk image cropped rather than a mosaic. Nice to see the H-Alpha narrowband filter on this, though it prompts another question - would the longer w/l IR-PASS 742nm+ give a sharper image or does a narrow window at 652nm trump this?

Jake

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opticalpath

opticalpath

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Nice to see the H-Alpha narrowband filter on this, though it prompts another question - would the longer w/l IR-PASS 742nm+ give a sharper image or does a narrow window at 652nm trump this?

Jake

I wondered the same - i.e. does the narrow window offer a benefit of its own, or is the longer wavelength light the only or significant factor? I suspect the IR passband filter would win out ...... but I don't have one of those fitted as standard to my deep sky camera set up. The other problem is that I was at the short exposure limit for the camera - any wider passband and I would not have been able to handle the extra light (never thought I'd say that!)

And yes, it's cropped from a full frame (62' x 46') image

Adrian

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SnakeyJ

SnakeyJ

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I wondered the same - i.e. does the narrow window offer a benefit of its own, or is the longer wavelength light the only or significant factor? I suspect the IR passband filter would win out ...... but I don't have one of those fitted as standard to my deep sky camera set up. The other problem is that I was at the short exposure limit for the camera - any wider passband and I would not have been able to handle the extra light (never thought I'd say that!)

And yes, it's cropped from a full frame (62' x 46') image

Thanks Adrian for the response, I hadn't considered the exposure limits on the camera but this is a proper piece of deep sky imaging kit, which makes the result even more pleasing! Sure its quite fun and something of a novelty to image a target is less than a minute! Hopefully conditions yesterday and tonight allow you to get back to some deeper/fainter and more challenging subjects ;)

I'm going to try for this NEO tonight, but might also have a stab at the moon with IR-PASS once it rises!

Cheers - Jake

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opticalpath

opticalpath

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How does H-Alpha work on the moon? I understand that it's used on the Sun and Nebula because they are made of Hydrogen but isn't the |Moon made of the same stuff as the Earth?

P.S Stunning image!

Thanks for the kind comment! Think of the Moon as 'white', i.e. reflecting a full spectrum of light; it's not doing anything special to produce light at H-alpha wavelength (as an emission nebula does, for example.) In this application, the Ha filter is just being used as a dark red filter, to cut down the light to a manageable level and to restrict the view to the deep red end of the spectrum. Under typical conditions, red (or IR) light is less disturbed by the atmosphere than blue so usually gives a steadier image for Moon and planets.

Adrian

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opticalpath

opticalpath

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Thanks Adrian for the response, I hadn't considered the exposure limits on the camera but this is a proper piece of deep sky imaging kit, which makes the result even more pleasing! Sure its quite fun and something of a novelty to image a target is less than a minute! Hopefully conditions yesterday and tonight allow you to get back to some deeper/fainter and more challenging subjects ;)

I'm going to try for this NEO tonight, but might also have a stab at the moon with IR-PASS once it rises!

Cheers - Jake

It's definitely the shortest integration I've ever done with this setup, Jake; comparable to bias frames I suppose! However, with a download time of 20+ seconds per image, it's not going to replace a 30 fps planetary camera any time soon!

Good luck with the NEO tonight.

Adrian

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