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Multispectral Captures with Lodestar and Ultrastar Mono Cameras


Dom543
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I am starting this thread to serve as a retrievable home for my multispectral captures this coming summer. Those, who are interested in the multispectral technique of using monochrome cameras with filters to make near-real-time color captures, will be able to find my captures here together. I am not a high volume producer. I like to spend some quality time with each of my targets, trying to understand, explore and appreciate them in various ways and through various views. As a result, I typically look at only one to three objects per night. I also am in Seattle now, where weather doesn't always cooperate. So this will be a slow growing thread.

Thank you for bearing with me and for checking back periodically, when new posts move the thread to the top of the forum list.

Clear Skies!  --Dom

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M51 in colors with Lodestar mono

M51.Whilpool.Galaxy_2016.5.7_00.32.06 - SGL.jpg

I have been trying to capture the blue of the star forming regions in galaxies for some time but have not been satisfied with past results. This capture is stacked together with the multispectral capabilities of LodestarLive v.3.0. Three 30 sec exposures were mean stacked with each of the R. G and B filters, 9 frames total. My Meade 10" SCT was used focally reduced to about f4.0. Unfortunately no darks were used and I forgot to turn on defective pixel removal,  I apologize for the few stray pixels.

The colors are subtle but the photons had a long way to travel to end up on the sensor of my camera. And the final stretch of their journey was though the vapor laden moist air typical for the Pacific Northwest. But the blue is there and it is only, where it should be, not everywhere as if the entire galaxy had been dipped into blue paint. To see this I made a 500% zoom of a section of the galaxy in an image editor and pushed up saturation to the max. This way one can see the color of each pixel individually. There are lots of colors captured other than blue. Areas where red and green pixels mix yield the rusty brown color characteristic of galaxies. The blue is in blobs along the main spiral arms, where the star forming regions are concentrated. (You may have to click on the picture below to see the individual pixels in full resolution. I also want to mention that this zoom is from the above image file processed and saved by StarlightLive. Not form the FITs data file.)

M51_PixelZoom_60%- SGL.jpg

 

To illustrate the difference that the incorporation of the multispectral features into StarlightLive make, I also include the best result of my attempts from almost exactly a year ago. That capture was made with a Lodestar x2 color camera and I tried to enhance it by also including in the stack frames made with a blue filter. This is similar to what we are doing now as multispectral. But at that time one could not assign frames individually to the color channels. The only way to bring out some of the blue was to reduce the brightness of the red and green components making the overall image rather dark. The progress between last year's picture and this year's image is a direct result of Paul's hard work to implement the multispectral technique in StarlightLive.

M51.Whirlpool_2015.5.8_21.57.41.jpg

 

The lead image of this post has been captured during our weekend camping trip with my wife to the Wenas Wildlife area East of Seattle. We didn't encounter any wildlife, except wild flowers going really wild. Below is a photo of our telescope at our chosen site, as we were setting up after arrival around sunset. The Meade 10" SCT is sitting on a CGEM mount. The computer with its 17" screen is on the spreader shelf of the mount and the environmentally incorrect lead-acid deep-cycle battery powering everything is conveniently covered up by a multispectral grouping of yellow asters and blue lupines.

TelescopeSetup_SGL.jpg

 

Finally, since I still have space within SGL's generous file size allowance, here is a close-up of the fully armed telescope for those of you, who like equipment.  To the 10" SCT is attached a flip mirror with built in x0.63 focal reducer and holding the Lodestar x2 monochrome camera. Piggybacking on top is a 180mm Nikkor f2.8 ED camera lens with an SX-825 monochrome camera for wide field views.

TelescopeCloseup_SGL.jpg

Clear Skies!  --Dom

 

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Hi Dom, the colours in your M51 look very 'natural' If you know what I mean, and as you say, you have the opportunity to play with the saturation to do more analysis as you observe, and capture the results. I'm looking forward to seeing how you get on, as I also have a monochrome Lodestar with LRGB filters. I was pretty pleased with my first attempts and am looking forward to trying out a range of objects, particularly some of the small colourful planetaries. I shall watch this thread with interest.

 

Edited by RobertI
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Hi Dom. What brand color filters are you using?

I have a RGB image of M51 taken a few nights ago sitting on my laptop at home. I will try and remember to post it when I get home. If I recall, it was similar to the first capture you linked above. If I recall correctly, the core was a little over-saturated and I thought I could make a better attempt so never posted it.

The forecast is for clear skies this evening, so I may give it another shot.

Thanks for the excellent thread!

 

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Hi Brandon and Others,

I should have but forgot to say in the first post that anyone is more than welcome to post multispectral images on this thread. That way people interested in this technique can can use this tread as a resource. The problem with the CN EAA forum is that everyone is posting their images on the gallery thread now.  There is no topical grouping  and is very difficult to find the particular images one is interested in.

Clear Skies!    --Dom

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Hi Dom. Thank you, I totally agree about the forum on CN not being optimal. I will post a few multi-spectrum images I captured back on the 6'th. All captures with the SX-825 (Ultrastar) and Astrodon RGB colour filters.

Here is the M51 mentioned earlier, 4x30s each RGB

cacc0d827c91196092bf86898a8ae10b.1824x0_

NGC 3242 Ghost of Jupiter. This one is 2x15s each RGB:

88abcc91f60210a23e9506057d0669fc.1824x0_

 

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  • 1 month later...

Eastern Veil (aka Network Nebula) in Hubble Palette

NGC6992.E.Veil.Sii.Ha.Oiii_2016.6.6_02.12.08.jpg

3x60 sec exposures with each of S-II, H-alpha and O-III narrowband filters mean stacked in StarlightLive v.3.0. Red is Sulfur, Green is Hydrogen, Blue is Oxygen.

The Veil is surprisingly rich in Sulfur. The only nebula I encountered this far, where all three components are present in approximately with the same intensity. Sulfur and Hydrogen overlap significantly resulting in the rusty brown and golden yellow colors. But closer inspection shows that there also are pure Sulfur (red) and pure Hydrogen (green) strands. Oxygen is mostly well separated. This nebula really benefits from the Hubble palette that assigns S-II and Ha to different base colors. Otherwise they would be both shades of deep red and practically indistinguishable. This would be nice in higher resolution. and larger field. Next time I should try it with the Ultrastar.

Equipment used: CGEM mount, Meade 10" f6.3 SCT, 3.3 reducer, TS manual filter drawer, Baader 7nm and 8.5nm filters, Lodestar x2 mono camera, StarlightLive v3.0. Taken from Seattle under full light pollution but no moon.

Clear Skies!  --Dom

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Terrific result Dom and an informative commentary; this is a fascinating object with all three NB filters and worth spending some time studying your results. I am also increasingly amazed what can be achieved with the diminuitive Lodestar! Nice work.

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Eastern Veil in Hubble Palette Fast "Draft Mode"

As a default, I usually stack three frames, in mulispectral mode three frames with each filter. But this time, before I started with the main capture, I made a fast trial capture to see how the relative strengths of the three channels will work out. This was made of only of single frames with each of the three filters, i.e. every channel is just one unstacked exposure. So this entire capture is only 1x60 Sii+1x60 Ha+1x60 Oiii = 180sec total. I post it here for those, who are in a hurry and prefer to have a complete three component Hubble palette image in just 3 minutes.

NGC6992.E.Veil.2016.6.6_01.48.13.jpg

To help to compare the original 3x60+3x60+3x60 capture and the fast 1x60+1x60+1x60 "draft mode" image, I copied them side by side. I also rotated them 90 degrees and reduced the resulting image to 80% to better fit the web page format. To the right is the draft capture.

NGC6992.E.Veil_2016.6.6_dual_80%.jpg

I believe that slider settings were about the same for both images. The draft mode image doesn't seem to badly suffer from the rough texture effect of unstacked captures. Stacking of the three channels appears to have sufficient smoothing effect to result in images that are o.k. for internet posting. At least for the 1/2" Lodestar image size. If one enlarges the images to 200%, then the difference in smoothness is more pronounced.

The most noticeable difference between the two captures is in their color balance. The draft mode image is much colder. This is the result of the fact that the weakest signal, which is the red Sulphur in this case, suffers the most from the lack of stacking. I elaborated more on this on the multispectral step-by-step thread here https://stargazerslounge.com/topic/271785-multispectral-starlightlive-captures-step-by-step/?do=findComment&comment=2978458. There is simply not enough data in a single 60sec Sulphur exposure to stretch it more aggressively. A possible way to get more Sulphur and a similar color balance in the draft mode could have been to combine a 90sec S-II exposure with 60sec H-alpha and O-III exposures. But that's Monday morning quarterbacking...

Clear Skies!  --Dom

 

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Thanks Dom, very interesting. As you say the image in the right is colder in colour, but I notice the background sky and stars on the left image are redder and less natural looking to me. Based on your experience to date, would you try and adjust the colour on the left, or would you leave as is?

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Thank you Rob!

As you are pointing it out, I also notice that there are more little red stars in the background. That can have several different reasons. One is that with more stacking we record photons that are not caught by a single exposure. A second possibility is that the red channel was selectively stretched more on the 3+3+3 original image than on the 1+1+1 draft mode one. A third and possibly easiest explanation is that the black level cutoff was placed slightly higher for the draft mode capture. I don't have the exact slider settings and I usually save about a dozen of different displays of the same data each with different slider settings. Then I decide the next day at daylight, which one I find the most suitable for posting. I usually stop stretching, when the image stats to fall apart. So it is possible that the 3+3+3 capture had more red data and could be stretched further.

What I would do next time knowing what I learned from this exposure? I would probably increase the exposure time for the Sulfur channel to 90 seconds. That would yield a more balanced data file and provide more elbow room to play with the sliders. As I said in the original post, this was the first object that I encountered that allowed to use the same exposure times for all three channels. I was thrilled by this and used equal exposures. But still, Sulfur is a rare commodity in outer space (compared to Hydrogen) and deserves special attention and possibly longer exposure times. The other thing I would do the next time is, I would use my SX-825 (aka Ultrastar Sr.) camera instead of the Lodestar. Both the finer resolution and the 30% larger field would benefit this object.

Clear Skies!  --Dom

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Your company in multispectral work would be very welcome. With my schedule allowing only one or two nights for asto per month, this thread grow only very slowly.

I hope that you will ave good clear skies over the weekend.  --Dom

 

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Hi Rob,

The full 6992 in tri-NB should be very nice. The "head" of the nebula, which is cut off from my above capture is also very colorful.

Below is a link to my attempt from last summer with a 300mm camera lens. At that time I didn't have a S-II filter, so the capture is only Ha+Oiii. Coincidentally, the false color "Swedish" palette yields colors rather similar to the Hubble palette for this particular nebula. https://stargazerslounge.com/gallery/image/27962-300mm-f28-eastern-veil-aka-network-nebula-swedish-palette/

Looking forward to more multispectral company. Maybe we will hit the critical mass with all the colorful summer nebulae up there. The Veil may be the ultimate target for Hubble palette experimentation. It will still be conveniently located for at least the next two months. The Western part of the Veil (Witch's Broom) is also very pretty.

Clear Skies!  --Dom

Edited by Dom543
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Finally got a bit of clear sky late last night, and after fighting with mount issues I was able to make my first narrow-band multi-spectral image.

SX-825, linear, mean, 3x30s each Ha/OIII/SII, Hubble palette, 800x600 crop from original.

M.27.Dumbbell.Nebula_2016.6.29_00.04.00_

Still have lots to learn with multi-spectral narrow-band, but I have made the start!

Edited by Ain Soph Aur
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More experimenting with SLL narrow-band multi-spectral stacking, the Dumbbell is a nice target for this. This one is just OIII and Ha, with the Red channel a blend of OIII/Ha.

M 27 Dumbbell Nebula
(800x600 crop from original)

M.27_2016.6.29_23.46.24c.png

Camera: SX-825 mono
Telescope: Orion MN190 f/5.3
Software: Starlight Live v3.1, Linear, Mean
Filters: Astrodon Ha 5nm OIII 5nm
Stacking: 9m total integration
R: 3 x 30s Ha, 3 x 30s OIII blend
G: 6 x 30s Ha
B: 6 x 30s OIII

Edited by Ain Soph Aur
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Brandon,

By assigning exposures to more than one color channel simultaneously, you could shave off 3 min from the total integration time:

3x30sec Ha to Green + 3x30sec Ha to Green+Red + 3x30sec Oiii to Blue+Red + 3x30sec Oiii to Blue = 12x30sec = 6min

It is interesting that the central body turned purple as a result of adding red to blue but the 'apple core" didn't turn yellow as a result of green+red. In fact, the green didn't seem to have changed at all compared to the Hubble palette capture. I like that the green jumps out better against the purple than against the blue of the Hubble palette. 

Clear Skies!  --Dom

 

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Great thread Dom et al. I was motivated by it to produce a quick RGB of M51 last night. This is 4x15s in each of RGB using Baader filters. The 'colour noise' is quite strong with 15s subs -- I should have gone longer (I was also using defective pixel removal rather than darks which perhaps didn't help).

M51.rgb_2016.7.4_12.26.42.png

For comparison, here's a mono version (9x15s, so a little less overall exposure) also from last night.

M51_2016.7.4_01.11.29.png

Martin

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  • 1 month later...

Work kept me very busy all summer. I have not had a chance to do any astronomy since early June. Yesterday we had a clear night here in Seattle so I set up on the deck. Here is one result, another part of the Veil nebula in Hubble palette. The Veil is so rich in all three major narrowband components that I cannot stay away from it. The only other comparably rich and balanced object that I know of is the Crab nebula, which will be coming up soon on the Eastern horizon. To have something different, this time I used the SX-825 mono camera to see, if its finer resolution can capture more of the fine detail of the Veil.

Veil.6995_2016.8.30_04.12.39_75%.jpg

This time, also for a change, I tried sum stacking. Air transparency is never good in Seattle requiring longer exposures. Sum stacking achieves this goal without the need for guiding or overly aggressive stretching. Also, I noticed earlier, that the combination of the frames belonging to the different channels in multi-spectral does have a somewhat similar smoothing effect as stacking. At least in those areas, that are covered by more than one channel. So here is one concrete example, how it works out in real life.

3x60sec S-II + 3x45sec H-alpha + 3x60sec O-III, Sulphur is red, Hydrogen is green, Oxygen is blue. I have the Baader narrowband filters with 7.0-8.5nm passbands. I used my 10" Meade natively f/6.3 SCT with an Optec 3.3x focal reducer with 60mm reducer to sensor spacing, resulting in f/2.0 (poor man's Hyperstar). The SX-825 was cooled to -15C but I also used three dark frames. Just out of habit. The H-alpha exposures were intentionally chosen shorter so H-alpha doesn't overwhelm the weaker S-II. The software was the most recent version of StarlightLive and this capture would not have been possible without StarlightLive's unique multi-spectral capability. The original capture has been reduced to 75% in Microsoft Paint to fit the webpage format.

Clear Skies!  --Dom

 

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That's an impressive focal reduction! The results are great though and worth the effort. Well done on getting out again, things seem to hotting up again in this forum now the nights are getting longer. :) 

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