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umasscrew39

Multispectral Captures with StarlightLive and NB Filters

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umasscrew39    7

Over a year ago, Dom 543 had started a step-by-step method to perform such captures with NB Ha, OIII, and SII filters using SLL and a Lodestar X2 both here and in CN.   I tried this the other night using a Ha 7nm Baader filter on my 80mm APO triplet refractor scope and my UltraStar M for a 15 or 30s single exposure of M27.  I aligned the Dumbbell Nebula and captured a very nice B&W Ha image.   However, when I unchecked ALL under Exposure Channel Mask and checked only RED as suggested by Dom's procedure, the entire screen turned red, including the image, stars, and empty space.   Even the signal peak on the graph was red instead of white.  Dom's procedure for M27 started with the OIII filter followed by the Ha filter but I did not have an OIII filter to follow his procedure exactly.  Besides, I do not see why that would make a difference.  Any ideas as to what is causing this all red image I am getting?    

Edited by umasscrew39

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Dave In Vermont    4,896

Ha & SII Filters transission-bands are firmly in the Red part of the spectrum. So this would go a ways to explain why it's 'making-you-see-red.' :p (sorry - I couldn't resist) Look at this graph of a typical Ha-Filter, taking note of what's coming through -

 

h_alpha_ccd_35nm_curve.jpg.a1d89c24ff8e0a1a23c513cfd99a1d0a.jpg

 

This shows the 620nm through about 660nm passband of this type of filter.

Now look at the Astronomik OIII, which also shows it having a portion of Ha and SII being allowed through (on the right) -

 

5a1665867832f_OIIIAstronomikTransmission.png.1f33dfe79741afd08f48c34f5b04ba34.png

 

So the OIII is allowing the 500nm area coming through, and this is a ways from the red-spectrum of the Ha and the SII. This accounts for an image only showing red as without the OIII-filter, you're only inviting the red-spectrum in. So my guess is you need the OIII-filter to get the results you want. There seems to be a method to Dom's technique and choice of filters.

I'd personally suggest the Astronomik OIII - CCD model filter. It has the brightest image of most OIII-filters available new at this writing.

Hope this helps,

Dave

 

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RobertI    1,002

Can you clarify what you were hoping to see? I am assuming you were hoping for a Muticolour image if some sort? I have done multispectral and am saying this from memory, so may be completely wrong, but if all you have is a mono cam and an Ha filter, then all you can produce is a B&W image taken without the Ha filter (by taking an exposure with the 'All' checked) with some red Ha superimposed (by taking an exposure using the filter with the 'Red' checked). You would view the finished product with 'All' checked to get a B&W image with red Ha superimposed.

For information when viewing the final image if you uncheck 'All' and only check red, you will see red, if you only check blue you will see blue, if you check green, you will see green. 

Hope that helps (and I hope its right!)

Rob

 

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Martin Meredith    1,470

Exposure Channel Mask defines which logical channels receive the signal from the sensor. If you collect H-alpha with 'all' (in Exposure Channel Mask) checked, you get H-alpha on all channels and when you display it combined it appears as monochrome. If you collect with just 'red' selected, then when you 'combine' it  it only contains information on the red logical channel, and so when examine it with the 'Display Selected' unchecked (this displays the combined channels), you will see a red signal as there is nothing in the G and B. 

However, if you were to look at your red-only signal with 'Red' checked and 'Display Selected' checked, you should see a mono signal. For maximum clarity, by 'red' selected, I mean 'red' in the 'Channel Selection' part of the 'Display Processing' pane, and not 'red' in the Exposure Control' pane...

This is M27 in H-alpha, O-III and S-II separately (i.e. looking at the red only, green only, blue only respectively), with 'Display Selected' checked

HOS.thumb.png.83281aefeb2a37114627640bcf83f11b.png

And this is when combined (with 'Display Selected' unchecked)

M27_HOS.0.25_2015.9.1_23_55_04.png.906c296bdfad452642fbc15ef3b65e66.png

 

HTH

Martin

Edited by Martin Meredith
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umasscrew39    7

Thank you all for your comments.

Dave- thank for the info.  I have both Baader and Astronomik filters so will try both and I just received my OIII and SII filters to try.

Rob- I have both the M and C versions of the UltraStar and have dozens of Ha images with the M camera and some with the C- no problem doing those.  I'm specifically interested in using the M camera to get the multi-color image that Martin displayed.

Martin- thanks much for the description of the settings and images and help again, as always.  

  - just so I am perfectly clear and a couple of more questions:  

  • "If you collect H-alpha with 'all' (in Exposure Channel Mask) checked, you get H-alpha on all channels and when you display it combined it appears as monochrome." ---  UNDERSTOOD and have done this 

 

  • "If you collect with just 'red' selected, then when you 'combine' it  it only contains information on the red logical channel, and so when examine it with the 'Display Selected' unchecked (this displays the combined channels), you will see a red signal as there is nothing in the G and B. ---UNDERSTOOD; this is what I was doing and getting everything red (which I think was my mistake)

 

  • if you were to look at your red-only signal with 'Red' checked and 'Display Selected' checked, you should see a mono signal. For maximum clarity, by 'red' selected, I mean 'red' in the 'Channel Selection' part of the 'Display Processing' pane, and not 'red' in the Exposure Control' pane..." --- have not tried this; QUESTION: when I check 'Display Selected' , do I leave 'Modify All 'and 'Auto Align' checked??

 

  • "And this is when combined (with 'Display Selected' unchecked)"----  THIS IS THE END RESULT I AM LOOKING FOR; SO GET THIS THIS THE FINAL SETTINGS ARE...

Display Selected - unchecked (thus, 'Modify All' and 'Auto Align' are still checked)- correct?

 

- I assume it does not matter which order I use the filters just as long I select the appropriate color selected when taking my exposures, e.g., 2x30s of each stacked

 

Sorry for the additional questions.

 

Thx much,

Bruce

 

 

 

 

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Martin Meredith    1,470
1 hour ago, umasscrew39 said:

 

  • if you were to look at your red-only signal with 'Red' checked and 'Display Selected' checked, you should see a mono signal. For maximum clarity, by 'red' selected, I mean 'red' in the 'Channel Selection' part of the 'Display Processing' pane, and not 'red' in the Exposure Control' pane..." --- have not tried this; QUESTION: when I check 'Display Selected' , do I leave 'Modify All 'and 'Auto Align' checked??

 

  • "And this is when combined (with 'Display Selected' unchecked)"----  THIS IS THE END RESULT I AM LOOKING FOR; SO GET THIS THIS THE FINAL SETTINGS ARE...

Display Selected - unchecked (thus, 'Modify All' and 'Auto Align' are still checked)- correct?

Hi Bruce

Re the Modify All/Auto Align, with respect to the current question it doesn't matter whether you check them or not. Most of the time auto-align does the right thing but occasionally the colour channels need to be adjusted manually and independently. In this case I uncheck Auto Align and uncheck Modify All, select each channel one by one, and alter their individual brightness and contrast values in order that their histogram contributions line up well.

Re 'this is when combined'. Yes, to get the combination you must have 'Display Selected' unchecked, since the 'selected' in this case corresponds to the R, G or B that is checked in the row below. (It really means, display selected *only*). The semantics would be clearer if the logical were to be reversed and the checkbox said 'Combine channels'.

Filter order doesn't matter and you can go round several times topping up the data. For RGB imaging I find the blue channel typically weakest so I tend to start with R, then G, then B, which also corresponds to the order I have those filters in my filter wheel (so it doesn't have to go all round the loop each time). Starting with a weak channel might lead in some cases to insufficient stars to align on I guess. The same would apply to narrowband -- best in my opinion to start with the strongest signal, usually H-alpha. If you have Sulphur it tends to be very weak, although the likes of the Crab (as well as M27) do have some.

Martin

 

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Robrj    98

I usually start with H-Alpha as well. 

One additional thing, when you do "Display Selected" and then "Save" the image, you'll get a separate monochrome image that contains only that channel.  

So for instance, if you did a SHO capture (S-II to Red, H-alpha to Green and OIII to Blue), you can select "Display Selected" on each channel and see how they contribute to the overall image.  In this case select "Red" would show an S-II only monochrome image, selecting "Green" would show an H-Alpha only image and selecting "Blue" would show a O-III only image.  Each could then be saved as a separate capture.  Same with a OSC image.  You could save the Red channel by itself.

For instance, here's an image of NGC1931 both shots are from the same image, one is saved with "Display Selected" off (full color)  The 2nd is selected with "Display Selected" and "Red" then saved which is an H-Alpha only image.

HOO (H-alpha to red, OIII to blue/green)

1091875f-94c7-4bb7-a5b4-8122bd7d4b46-148

 

Here is just the H-Alpha channel

6bda8398-33c2-4a5f-a722-674bc306cb3e-148

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umasscrew39    7

I finally got around to trying the NB filters on M42.  These were taken on an 80mm APO Triplet (f/6) with an UltraStar M using SLL, v 3.3.  

Both images were taken using Baader H-alpa, O-III, and S-II NB filters, 3x20s per filter stacked.  

First image is using the Hubble Palette and the second is using the CFHT Palette.

 

M42 Hubble Palette.png

M42 CFHT Palette.png

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Robrj    98

Very nice Bruce.   I like that CFHT Palette.

 

I forgot to post mine from November 21st.  Also done with an 80mm (Orion ED80T-CF) but with a Lodestar X2M.

IC443 in SHO (15x30s per channel)

Nj5GlnRNRCnM_1824x0_o_Q2CdQ1.jpg

 

M42 SHO (5x30s, then 10x5s per channel)

gLalmPXbu_au_1824x0_o_Q2CdQ1.jpg

 

M42 (5x30s, then 10x5s)

O2G2C42iuyl9_1824x0_wmhqkGbg.jpg

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umasscrew39    7

Thanks, Rob.

Very cool !!!  Glad our M42 images look alike :-)

Can't wait to keep exploring with this technique on my C11" with the hyperstar.

Thanks for your input and initial help.

Bruce

  

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Robrj    98
8 minutes ago, umasscrew39 said:

Thanks, Rob.

Very cool !!!  Glad our M42 images look alike :-)

Can't wait to keep exploring with this technique on my C11" with the hyperstar.

Thanks for your input and initial help.

Bruce

  

Since I did mine just before Thanksgiving, my wife commented that the HOO shot looks like a turkey.  :) 

 

M1 is another good target.  It should be awesome in the C11.

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shirva    257

The new book by Steve Richards, black art or magic bullet is a great book on processing images,, recommended

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RobertI    1,002
6 hours ago, umasscrew39 said:

I finally got around to trying the NB filters on M42.  These were taken on an 80mm APO Triplet (f/6) with an UltraStar M using SLL, v 3.3.  

Both images were taken using Baader H-alpa, O-III, and S-II NB filters, 3x20s per filter stacked.  

First image is using the Hubble Palette and the second is using the CFHT Palette.

 

M42 Hubble Palette.png

M42 CFHT Palette.png

Fantastic captures, coped very well with the high dynamic range, lovely detail and colour.

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