filter for colour one shot for solar shooting?

[sil]

While not strictly spectrography I can see it'll take a Merlin ;) to answer accurately.


I'm replacing my zwo asi120mc (colour cam) soon with another colour zwo. I appreciate a mono camera and maybe filter set is a better option but beyond what my needs, budget and capabilities allow this year. I know there are some good monos at a price I could afford but then I'm restricting my useage that the colour option is going to allow, a good mono is the next purchase target though, just not soon.

So I was considering "permanently" installing on my coronado rig instead. My question is are there any filters I could put on the asi120mc to maybe give the best contrast/clarity of the Ha view. I was thinking maybe something that reduced capture of the zwo's noisiest colour channel? Of course I'd have to convert my capture to greyscale . I'm thinking the result of my processing is a highly detailed and contrasting grey image I can then colourise if I need from there. I'd be keen to get good shots of prominences.

Any advice on improving the zwo for Ha solar imaging? The coronado is 40mm and double stacked from memory. I'm unable to use eyepieces safely so it doesn't get much use these days but the zwo works fine and I can install it on the coronado rig. I have built a peltier cooler on the zwo too.

I suspect the coronado is already filtering all the unwanted spectra to provide a good view and I may as well just capture with the zwo as is, maybe splitting channels out and working with the cleanest looking for what I want. I dont anticipate this configuration to be used for any spectra measurements, just pretty pictures :) any advice towards these ends? or hacking the 120mc to a 120mm?

cheers

[Merlin66]

Sil,
A double stacked SM40 will effectively filter the solar light to a very narrow 0.4A bandwidth centred on Ha. No other light get through.

The RGB camera response will depend very much on the overlap of the Bayer Matrix filters within the camera. There's no easy way of adding additional filters to isolate the Ha wavelength.

Summary: Although the incoming light is 100% monochromatic (red, Ha) there may be a response recorded on the R and G pixels due to the Bayer filters. These should be ignored. Just work with the red channel.
Hope this helps.

[JA]

Hello M,

Yes there is indeed an extended response, surprisingly well past what would normally be considered blue or green and deep in to the red. In fact all the way up to Ha at 656nm with a
QE of ~8% in the GREEN Channel,
QE of ~6% in the BLUE Channel
compared with an obviously higher
QE of ~52% in the RED Channel.

Data is read from ASO120 Colour QE graph attached below, from webpage:https://astronomy-imaging-camera.com/products/usb-2-0/asi120mc-color/.

Even though the QE is not huge in the blue and green, it would be a shame to discard it, without at least a look see, especially as it would already be ultra-narrow band filtered by the solarscope. It would be worth a try perhaps with some scaling of the various intensities to counteract/perhaps to try to equalise the differing QE between channels (try, but watch noise in so amplifying/doing), and then put in to monochrome for final result.

Best
JA

[sil]

thanks guys. So basically there's nothing extra to be done with the combo physically really to get a better picture at the end of the day, more experimenting with what spliting the channels might offer to enhance features. thats fine until i get a mono camera later on :) at least want to put the 120mc to use instead of gathering dust, cant stand working gear sitting idle.