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Sh2 180 HA  Takahashi 180 ED, 





    
        

            jerryyyyy

Sh2 180 HA Takahashi 180 ED

Technical card

Resolution: 3230x2454

Dates:Jan. 4, 2019Jan. 5, 2019

Frames:
Astrodon Blue Tru-Balance E-Series Gen 2: 12x240" bin 1x1
Astrodon Green Tru-Balance E-Series Gen 2: 12x240" bin 1x1
Astrodon H-alpha 5nm: 20x1800" bin 1x1
Astrodon Red Tru-Balance E-Series Generation 2: 12x240" bin 1x1

Integration: 12.4 hours

Avg. Moon age: 28.56 days

Avg. Moon phase: 1.31%

Astrometry.net job: 2456285

Locations: Stanford Faculty Observatory, Stanford, California, United States

Data source: Own remote observatory

Description

We have brought back to like the venerable Takahashi 180 ED. A friend gave the mirror a bath (once every 12 years whether you need it or not). Collimation is not perfect, but perfection is the enemy of good at F2.8.

I may try to do RGB HA but you lose the detail. This is a pretty dull object. Narrow Band is best viewed in the full screen.

The last image that highlights the objects is rather complex processing, but I'll put it here for the record:

There are two main steps, first to make a COMBO composite HA_RGB, the second to use a MASK to just present the nebula with the stars in the background.

COMBO in Photoshop (variant from many people)

Star Size Adjustment Bring up the Channels window (Windows > Channels) in the RGB image. 

Creating the LRGB Composite Click on the Red channel to make it the only active channel.
This makes the Red channel visible in the image window. 
Press Ctrl-A to select the entire image, then Ctrl-C to copy.
The next step is to create a new image that is a composite of the H-alpha and Red images. 

Extracting the Red Channel Select the H-alpha image and press Ctrl-V to paste the Red channel image as a new layer in top of the H-alpha image. 
Change the Opacity setting to 20-30%. (20% shows more HA)
This creates a blend of the Red and H-alpha images. 
The detail of the H-alpha image is retained, but the larger and more numerous stars from the Red image become visible as well.

Creating an HaR Image Save this new HaR image as a separate file.  (Flatten)
This will be used both for the Luminance image and also to create a new RGB image.
Press Ctrl-A and Ctrl-C to select the entire HaR image and copy it.  (Flatten Layers)
Go back to the RGB image and make sure the Red channel is still the active channel. 
Press Ctrl-V to paste the HaR image into the Red channel.
Once the images are aligned, click on the RGB channel to activate the entire image again.
This method uses the HaR image to enlarge the star sizes in the Luminance channel to better match the larger stars of the RGB.

Creating a New RGB Copy the HaR image and paste it as a new layer on top of the new RGB image.  (Need to make new layer)
Change the Opacity to 30-40%.  (40% shows more HA but also more pink)
Change the Blending Mode in the Layers window to Luminosity.
This creates the new HaRRGB composite.

MASK in Photoshop:

File, Scripts, load files into stack (HA_RGB from above plus Regular RGB with the Stars)
Layer, Mask, Reveal All
Brush Tool
Foreground set to Black
Brush open the nebula
Layer Merge Down

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Author

jerryyyyy
jerryyyyy
License: None (All rights reserved)
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Photoshop at work

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Sh2 180 HA  Takahashi 180 ED, 





    
        

            jerryyyyy