Celestial hemisphere:  Northern  ·  Constellation: Cepheus (Cep)  ·  Contains:  EH Cep  ·  FN Cep  ·  FR Cep  ·  FU Cep  ·  FV Cep  ·  FW Cep  ·  FY Cep  ·  HZ Cep  ·  Iris Nebula  ·  LBN 483  ·  LBN 487  ·  LDN 1168  ·  LDN 1170  ·  LDN 1171  ·  LDN 1172  ·  LDN 1173  ·  LDN 1174  ·  NGC 7023  ·  PGC 2817439  ·  PW Cep  ·  SX Cep  ·  T Cep
Iris Nebula (August 2023), Paul Macklin
Powered byPixInsight

Iris Nebula (August 2023)

Revision title: Slight increase to vibrance and saturation

Iris Nebula (August 2023), Paul Macklin
Powered byPixInsight

Iris Nebula (August 2023)

Revision title: Slight increase to vibrance and saturation

Equipment

Loading...

Acquisition details

Loading...

Description

I imaged the Iris Nebula for 3 nights from my backyard, sans filter, and combined the best 16 hours of 5 min subs. 

I've worked to improve my processing compared to prior attempts (in APP and PS).

Version 5 (current): Here, I've reexamined my APP processing, realizing that for heavily blue scenes like this one, it auto-saturation overstretches the reds. I also made modest use of APP's built-in sharpening, and exported a broader stretch to get the molecular cloud details. 
In APP: 
  • Regular light pollution processing in APP at 30% stretch
  • Reduce star size by 10%, reduce intensity by 20%
  • Black body star calibration
  • Set sharpening at 0.5%. Increase the HL value to 20 to deal with the bright central star
  • Save at 30% stretch, 2 sigma, 0 base

In PS: 
  • NoiseXTerminator (60% denoise 80% sharpen)
  • Topaz (low light profile, 1% reduce noise, 0% sharpen, 50% recover original detail)
  • Unsharp mask (75%, 1.5 pixels)
  • Auto-contrast
  • Curves (linear)
  • Adjust Hue/Saturation:
    • Red: -10 saturation, +5 lightness to tone down the brown molecular clouds
    • Yellow: -5 saturation, +5 lightness
    • Cyan: +20 saturation, -10 lightness to ehlp emphasize the iris
    • Blue: +15 saturation, -5 lightness to further emphasize the Iris
    • Magenta: +15 saturation, -5 lightness to preserve the purples in the Iris (little effect)

  • Color balance (mids): magenta/green: -15 (the scene was a little green-blueish)

*****

Version 1: 
In APP: 

  • Regular light pollution processing in APP at 30% stretch
  • Reduce star size and intensity by 10%
  • Save at 20% stretch, 3 signa, 0 background

In PS: 
  • NoiseXTerminator (60% denoise 60% sharpen)
  • Topaz (Low light profile, 1% denoise, 0% sharpen)
  • Unsharp mask (150%, 1.5 pixels)
  • Auto-levels (use their black level, reset gamma to 1)
  • Curves (use a custom "molecular clouds" profile that I'll show in a moment)
  • Auto-contrast (not much effect)
  • Curves (use a custom "comet" profile that I'll show in a moment)
  • Auto-levels (use their black point and a 1.1 gamma)
  • Adjust Hue/Saturation:
    • Red: -10 saturation, +10 lightness to tone down the brown molecular clouds
    • Blue: +20 saturation, -10 lightness to further emphasize the Iris
    • Magenta: +10 saturation, -5 lightness to preserve the purples in the Iris


Version 2: Here, I've tried to simplify the processing and make sharpening a little less "crispy" and reduce artifacts. 
In APP: 
  • Regular light pollution processing in APP at 30% stretch
  • Reduce star size and intensity by 10%
  • Save at 20% stretch, 3 sigma, 0 background

In PS: 
  • NoiseXTerminator (60% denoise 80% sharpen)
  • Unsharp mask (50%, 1.5 pixels)
  • Auto-levels (use their black level, reset gamma to 1)
  • Curves (use a newer custom "molecular clouds 2023" profile that I'll show in a moment)
  • Adjust Hue/Saturation:
    • Red: -10 saturation, +50 lightness to tone down the brown molecular clouds
    • Blue: +10 saturation, +0 lightness to further emphasize the Iris
    • Magenta: +5 saturation, +0 lightness to preserve the purples in the Iris



Version 3: Here, I've tried to simplify the processing and make sharpening a little less "crispy" and reduce artifacts. 
In APP: 
  • Regular light pollution processing in APP at 30% stretch
  • Reduce star size and intensity by 10%
  • Save at 20% stretch, 3 sigma, 0 background

In PS: 
  • NoiseXTerminator (60% denoise 80% sharpen)
  • Topaz (low light profile, 1% reduce noise, 0% sharpen, 50% recover original detail)
  • Unsharp mask (50%, 1.5 pixels)
  • Auto-levels (use their black level, reset gamma to 1)
  • Auto-contrast
  • Curves (use a newer custom "molecular clouds 2023" profile that I'll show in a moment)
  • Curves (use a newer custom "molecular clouds" profile that I'll show in a moment)
  • Adjust Hue/Saturation:
    • Red: -10 saturation, +5 lightness to tone down the brown molecular clouds
    • Yellow: +0 saturation, +5 lightness
    • Cyan: +10 saturation, +0 lightness
    • Blue: +10 saturation, +0 lightness to further emphasize the Iris
    • Magenta: +5 saturation, +5 lightness to preserve the purples in the Iris

Version 4: Minor variation on V3

Comments

Revisions

  • Iris Nebula (August 2023), Paul Macklin
    Original
  • Iris Nebula (August 2023), Paul Macklin
    B
  • Iris Nebula (August 2023), Paul Macklin
    C
  • Iris Nebula (August 2023), Paul Macklin
    D
  • Iris Nebula (August 2023), Paul Macklin
    E
  • Final
    Iris Nebula (August 2023), Paul Macklin
    F
  • Iris Nebula (August 2023), Paul Macklin
    G

B

Title: More subtle processing

Uploaded: ...

C

Title: v3: Curves more like v1, sharpening and colors more like v2

Uploaded: ...

D

Title: A bit more like v1, but with better sharpening and hue/saturation

Uploaded: ...

E

Title: Reworked processing front-to-back

Description: Realizing that AstroPixelProcessor's auto-saturation tends to over-stretch reds in blue-heavy scenes like this one, I reworked most steps. And now let's leave well enough alone!

Uploaded: ...

F

Title: Slight increase to vibrance and saturation

Description: Same as previous (v5), only slightly bumping vibrance and saturation by +10 to increase focus on the Iris.

Uploaded: ...

G

Title: Evolving equipment and technique

Description: Here are three attempts at the Iris Nebula in 2021, 2022, and 2023. There's always room to improve, but I'm happy at the journey so far!

Uploaded: ...

Sky plot

Sky plot

Histogram

Iris Nebula (August 2023), Paul Macklin