ZWO ASI224???

[gnomus]

I have done a small amount of solar imaging with my ASI 120 MM-S and my Quark.  I do much prefer a "colour" Ha image and, as a result, I always false colour my solar shots using PS.  These never quite match up to the gorgeous rich colours that I see when using the Quark visually though.  

I wonder if there would be any mileage in shooting the Quark shots with an OSC - I was thinking specifically of the new ASI 224 which seems to be achieving great things on planetary images.

Has anyone tried anything like this? 

[JamesF]

I've still to get a good understanding of how the resolution of an image is affected when narrowband imaging with a colour sensor, but I think people have demonstrated adequately well that it's not impossible.

There are apparently however wavelengths at which the 224MC is not so hot and I have a nagging suspicion that one of them is the Ha band.

I'll have a dig about and see if I can find the post I read the other day that mentions it.

James

[JamesF]

No, it looks like it's the blue/UV end of the spectrum where the 224 isn't so hot.  Red sensitivity looks very good, so I'd assume that Ha would work well.  The main issue will be that you're only using one out of every four pixels.

James

[michael.h.f.wilkinson]

Please realize the colours you see are made in the brain. We appear to see varying colours but there is just a single wavelength there. Digital capture with a colour camera will not change that. True, people have shot solar H-alpha with a colour camera, but mainly because they already had one, and couldn't afford a monochrome yet. You will lose 3/4ths of the effective pixels, so you take a big hit in sensitivity.

As said shooting H-alpha with a colour camera is feasible, but the results of monochrome are invariably better

[Pete Presland]

I went through a period of using "false" colour in the processing of my HA solar images, but I don't now it is purely aesthetic and subjective anyway, it's the details that count.

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[gnomus]

Please realize the colours you see are made in the brain. We appear to see varying colours but there is just a single wavelength there. Digital capture with a colour camera will not change that. True, people have shot solar H-alpha with a colour camera, but mainly because they already had one, and couldn't afford a monochrome yet. You will lose 3/4ths of the effective pixels, so you take a big hit in sensitivity.

As said shooting H-alpha with a colour camera is feasible, but the results of monochrome are invariably better

That is a good point. The issue then is getting a decent set of "Color Balance" settings.............

Any suggestions??

[JamesF]

I went through a period of using "false" colour in the processing of my HA solar images, but I don't now it is purely aesthetic and subjective anyway, it's the details that count.

I actually find that some of the detail is easier to pick out in false colour images even though I know there's no new information there.  I imagine that's probably different for everyone though.

James

[michael.h.f.wilkinson]

The "fire-colour-map" I tend to use for my pseudo colour images is known to show details over a larger dynamic range than simple grey scale. It is aesthetically pleasing as well, but I do not claim it bears close resemblance to the "real" thing

BTW, technically false colour means mapping different wavelength bands  (eg IR, visual, UV) to RGB, pseudo colour refers to mapping monochrome to an RGB image through some look-up table

[JamesF]

That's interesting, Michael.  I'd not heard of that.

I can see that there's the possibility of an argument that colouring the image might move it into a range where the eye's cones are more receptive and it might therefore be possible to distinguish more detail, but I've not yet convinced myself that such a notion stands up to scrutiny.

Do you have any more details?

James

[gnomus]

The "fire-colour-map" I tend to use for my pseudo colour images is known to show details over a larger dynamic range than simple grey scale. It is aesthetically pleasing as well, but I do not claim it bears close resemblance to the "real" thing

BTW, technically false colour means mapping different wavelength bands  (eg IR, visual, UV) to RGB, pseudo colour refers to mapping monochrome to an RGB image through some look-up table

I've not heard of "fire-colour-map".  A Bing search turned up a number of interesting results, but nothing that seemed relevant to solar imaging.  Can you give me a bit more details of this please Michael?

Ta. 

[michael.h.f.wilkinson]

Nickname for the so-called Dark Body Radiator colour map. Mine is approximated like this

[JamesF]

Aha!  Thank you for that.

James

[gnomus]

Nickname for the so-called Dark Body Radiator colour map. Mine is approximated like this

...

I'm really sorry to be a pest, but what is that and where did you get it?  Again, Google/Bing searches for "Dark Body Radiator Colour Map" did not help me.  That doesn't look like Photoshop.

[michael.h.f.wilkinson]

I'm really sorry to be a pest, but what is that and where did you get it?  Again, Google/Bing searches for "Dark Body Radiator Colour Map" did not help me.  That doesn't look like Photoshop.

It can be found here https://root.cern.ch/drupal/content/rainbow-color-map

The image I show is from GIMP, but photoshop should also have that functionality

[Luke]

I have seem some lovely solar h-alpha images taken with a colour camera, but my vote would be go mono, then you know all the pixels can potentially record useful detail. And as already said, it should be just a single wavelength of colour anyway, which you could simulate in editing, you wouldn't be recording complex colour data like you might get with planets or even the moon.

[Pete Presland]

I actually find that some of the detail is easier to pick out in false colour images even though I know there's no new information there. I imagine that's probably different for everyone though.

James

I certainly think the inverted images can show more detail. That said, I guess it's all down to the skill of the person processing. Something which is not my strong point.

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[gnomus]

It can be found here https://root.cern.ch/drupal/content/rainbow-color-map

The image I show is from GIMP, but photoshop should also have that functionality

Jings that looks a bit complicated.  Am I supposed to download and install "ROOT"?  If I do this, do I then find some Filter or module within Photoshop that allows me to colourise my solar images?

[michael.h.f.wilkinson]

Jings that looks a bit complicated.  Am I supposed to download and install "ROOT"?  If I do this, do I then find some Filter or module within Photoshop that allows me to colourise my solar images?

No you simply use some colour curves to match the effect. I only referred to the CERN cite to show what the look-up table looks like

[gnomus]

No you simply use some colour curves to match the effect. I only referred to the CERN cite to show what the look-up table looks like

OK - that is a relief. Thanks for your help with this Michael.

Steve

[gnomus]

I adjusted one of my recent attempts - trying to replicate the curves shown in Michael's example above.  I got this:

Does this look close?

[michael.h.f.wilkinson]

That looks pretty close.

[gnomus]

That looks pretty close.

I'll take it! Thanks for your help with this Michael. I have saved my curve as a preset.

[JamesF]

I agree.  That looks pretty good to me.

James