First ever Ha image (M8 / Lagoon)
Posted 01 August 2013 - 07:42 AM
Location: Enfield, NS Canada
Camera: Canon XSi / 450D Gary Honis Full Spectrum modified
Filter: Astronomik 12nm Ha Clip filter
Telescope: Orion 8" F4 Astrograph
Mount: Celestron CGEM
Guiding: Celestron 80mm Guidescope with an Orion Starshoot Autoguider.
Subs: 2 x 1200s Total Integration is 40m
10 Darks/25 Bias/25 Flats/ added
Post-Processing: Pixinsight 1.8 RC7
Captured with: BackyardEOS 3
Bought the Astronomik 12nm Na filter from a fellow member and this is my first image. I could have gone 2400s but with the airport in sight and satellites I figured I better not. Had to toss out 1 20minute sub because of it. focus was a bit of a challenge with the filter. I don't know how those with the 7nm or less filters can focus. Now I need to grab some RGB and figure out how to integrate the Ha in with the RGB data!
Getting these two images was a challenge, after bumping into the scope not once but twice I had to redo the alignment. To add insult to injury, the finder hit the dome because I wasn't moving the dome with the scope, clearance issue. I don't think it damaged the gears, the shots turned out and the mosquitoes, omg, the mosquitoes!!! 1000's of them, eating them, getting them in my eye, ears and nose, where did they all come from. In the end you should have seen the PHD graph, LOL. It was off the charts but it held. It was also my first time using the newly released BackyardEOS 3. It is by far my favorite capture software, nice big numbers and letters and the new Bahtinov mask tool for focusing is the cats meow! well done. However for some reason the star image in live view mode was garbage, I had to switch to taking pictures, which made focusing oh so fun! not sure if its because 10x zoom is enabled or the Ha filter I was using but it was the worst time focusing ever. The bahtinov mask star was 3x time size in BYE 2 and I could see it over a good distance. Must have been me
All in all I think this turned out rather well for being a first time narrowband image.
M8_LAGOON_2x1200s_1600iso_Astronomik_12nm_H_Alpha-Redchanne_darks by AstroJeff, on Flickr
Posted 01 August 2013 - 03:04 PM
How do I focus with 5nm? With difficulty but I am all manual and It's not that hard once used to it - thankfully it is par focal with my SII and OIII which are even more difficult. But then with CCD an computer it's much different than a DSLR I suspect. Call it fun
There are ways you can stretch the Ha that will help bring back the textures and highlights though the center may be a bit tricky. The large dynamic range makes doing a DDP type initial stretch one good way to get it in the harness.
Having great data to play with is the name of the game though and yours looks very good !
Posted 01 August 2013 - 06:08 PM
Is my image typical what an Ha image should look like? was my process correct?
Here is the Pixi workflow for those interested:
DSS Exported to 16 Bit FTS
Opened in Pixinsight and immediately ran ScreenTransferFunction (non linear stretch) just to see what I had to work with.
I turned off STF
Cropped the image to remove the tiny frame left from stacking.
Ran a quick HistogramTransformation just to bright a little did NOT touch the background slider. I only adjust the Midtones
Ran another HistogramTransformation this time using a little more care what I stretch, I slightly adjusting the shadows slider while watching the clipped pixels count and making sure this number is as close to 0 as possible.
Ran ACDNR (noise reduction) while creating a lightness mask to protect the nebula.
Ran another Histogramtransformation adjusted Midtones and Shadows again watching the clipped pixel count.
(Now the fun part)
I extracted the Lightness.
Ran HistogramTransformation on the lightness using only the shadows slider and not caring if I clip any pixels, the key here is to make the background darker. You don't want to clip too many pixels, just make it noticeably darker than the reference image. (Make sure to keep as much of the dim nebula as you can)
Create a mask from this lightness frame.
Turn off Show Mask
Now I selected on the Histogramtransformation again making sure the primary frame is selected.
Now ONLY stretch the midtones (Don't go too crazy) you will notice only the nebula is stretched. the background doesn't brighten as much.
Ran an UnsharpMask (Just a VERY slight sharpening)
I now ran HDRMultiscaleTransform with 6 layers and 1 iteration with To Lightness and Lightness Mask checked (This enhances the dark knots and tones the core down to see detail in the core)
I ran HDRMultiscaleTransform with 4 layers and 1 iteration with To Lightness and Lightness Mask checked AND Deringing (Prevents donut stars, but if you have bright stars, create the starmask, invert the starmask to protect stars) I didn't have bright stars so I didn't bother.
I now ran 4 iterations of Curves boosting ONLY the red channel.
Grabbed the red channel and converted to grayscale.
Posted 01 August 2013 - 09:07 PM
No clue about PI as for me it's just a click or two in MaxImDL, hopefully someone that uses that platform can help. As to what is typical, I'd just do an image search in google adding 'narrowband' to the search string - there are very many results to look at for comparison. here are results from one I just did. I prefer the google image search to that on any specific site.
Posted 02 August 2013 - 05:25 AM
You certainly got to using the new filter quickly
I am looking forward to your next post.
Posted 04 August 2013 - 01:35 AM
Ha is 2x1200s and RGB is 7x120s Combined in Pixinsight using the HaRVB-AIP script.
Here is the RGB data only:
M8_7x120s_14m_ISO1600_RGB_DBE by AstroJeff, on Flickr
This is the HaRGB combine
M8_2x1200s_H_Alpha___M8_7x120s_RGB-ISO1600 by AstroJeff, on Flickr
Posted 04 August 2013 - 11:06 AM
I really like that you showed both RGB and HaRGB data.
Your processing looks really good.