Canon EOS M100 - SteveJustin1963/Telescope-Tec1 GitHub Wiki

Astrophotography with Canon EOS M100 & Linux (Lubuntu) — Full CLI Guide

Goal: Shoot 2 hours of 30-second exposures → calibrate + stack in Siril using .CR2 files

1. Overview: What You Need

Item	Purpose
Canon EOS M100	DSLR camera (RAW `.CR2` files)
Micro-USB cable	Connect to Linux (USB tethering)
UHS-I U3 SD card (16–32 GB)	Fast write speed (no delays)
Laptop (Lubuntu/Ubuntu)	CLI control + Siril stacking
Optional: DR-E12 dummy battery + power bank	2+ hour shoots

2. File Formats & Siril

FITS vs CR2

.fits = Astronomy standard (NASA, Hubble)
.CR2 = Canon RAW (your M100 files)
Siril opens .CR2 directly — no conversion needed

Never convert .CR2 → .fits unless using other tools.

3. Folder Structure

/home/sj/astro/session_20251113_1528/
├── lights/     ← Your sky photos (.CR2)
├── darks/      ← Sensor noise (lens cap on)
├── flats/      ← Vignetting fix (white surface)
├── bias/       ← Read noise (fastest shutter)
└── processed/  ← Siril output

4. CALIBRATION FRAMES GUIDE — Why & How

Frame	Purpose	How to Shoot	Quantity	Time
Darks	Remove hot pixels & thermal noise	Lens cap on, same ISO, shutter, temp as lights	10–20	10 × 30s = 5 min
Flats	Fix vignetting & dust	White T-shirt over lens, AV mode, same ISO, focus	10–20	10 × 1/100s = 1 sec
Bias	Remove camera read noise	Fastest shutter (1/4000), lens cap on, same ISO	20–50	20 × 1/4000s = 5 sec

Only lights contribute to the image. Calibration removes defects.

Step-by-Step: Shoot Calibration Frames

1. Darks (After Lights — Same Temp!)

Finish lights (2 hours)
Leave camera in same spot (same temp)
Put lens cap on
In camera: Manual → ISO 1600 → 30 sec → Drive: Single
Take 10–20 shots
Copy to darks/ folder

2. Flats (Same Session, Same Focus)

Keep lens on, same focus
Point at even white surface (T-shirt, sky at dusk, white wall)
Mode: AV (Aperture Priority) → f/5.6 → ISO 1600
Camera auto-selects shutter (1/100–1/500)
Take 10–20 shots (slight movement OK)
Copy to flats/ folder

3. Bias (Any Time)

Lens cap on
Manual → ISO 1600 → 1/4000 sec
Take 20–50 shots
Copy to bias/ folder

Copy to Folders (CLI)

After plugging camera

cp /media/sj/CANON/DCIM/100CANON/IMG_*.CR2  /home/sj/astro/session_20251113_1528/lights/
cp /media/sj/CANON/DCIM/100CANON/DARK_*.CR2 /home/sj/astro/session_20251113_1528/darks/
cp /media/sj/CANON/DCIM/100CANON/FLAT_*.CR2 /home/sj/astro/session_20251113_1528/flats/
cp /media/sj/CANON/DCIM/100CANON/BIAS_*.CR2 /home/sj/astro/session_20251113_1528/bias/

5. USB Tethering with `gphoto2` (Recommended)

Install

sudo apt install -y gphoto2

Test Detection

gphoto2 --auto-detect
 
# → Canon EOS M100 (normal mode)   usb:001,002

2-Hour Shoot Script (240 × 30s)

cat > ~/m100_usb_2hr.sh << 'EOF'
#!/bin/bash
set -e

LIGHTS_DIR="/home/sj/astro/session_20251113_1528/lights"
mkdir -p "$LIGHTS_DIR"

echo "Plug in M100 via USB. Set to Bulb, ISO 1600, f/2.8+"
echo "Starting 240 × 30s exposures..."

for i in {1..240}; do
  echo "Shot $i/240 at $(date +%H:%M:%S)..."
  gphoto2 --capture-image-interval=31 --capture-image
  sleep 1
  if ls /tmp/capture_*.CR2 >/dev/null 2>&1; then
    mv /tmp/capture_*.CR2 "$LIGHTS_DIR/IMG_$(printf "%04d" $i).CR2"
    echo "Saved: IMG_$(printf "%04d" $i).CR2"
  fi
done

echo "SHOOT COMPLETE! 240 images in $LIGHTS_DIR"
EOF

chmod +x ~/m100_usb_2hr.sh

Run

~/m100_usb_2hr.sh

6. FULL CALIBRATION + STACK in Siril (CLI)

cd /home/sj/astro/session_20251113_1528

cat > m100_orion.siril << 'EOF'
# Load light frames
load lights/*.CR2

# FULL CALIBRATION (uncomment when ready)
preprocess -dark=darks/*.CR2 -flat=flats/*.CR2 -bias=bias/*.CR2 -cfa

# Register (align stars)
register

# Stack (average)
stack avg

# Save final image
save orion_m100_calibrated

quit
EOF

Run stacking with calibration

siril-cli -s m100_orion.siril 2>/dev/null

View Result

siril orion_m100_calibrated.fits
# Press Ctrl+A → Auto Stretch

7. SD Card & Write Speed

Shoot	Size
240 × 30s	~6 GB
Recommended: SanDisk Extreme 32GB UHS-I U3	No delays

Write time: ~0.7s per 25MB → no gap between 30s shots

8. Power for 2+ Hours

Stock battery: ~1 hour with WiFi/USB
Solution:
DR-E12 dummy battery + USB 5V→8V step-up cable + 10,000 mAh power bank

9. WiFi Alternative (Not Recommended)

qDslrDashboard AppImage links broken (404)
gPhoto2 over USB is faster, more reliable
Avoid WiFi: slow, drains battery, drops connection

10. Test with Sample FITS (Already Downloaded)

cd /home/sj/astro/session_20251113_1528

cat > test_stack.siril << 'EOF'
load lights/*.fits
register
stack avg
save hubble_test_stack
quit
EOF

siril-cli -s test_stack.siril 2>/dev/null
siril hubble_test_stack.fits

11. Troubleshooting

Issue	Fix
`nmcli: command not found`	`sudo apt install network-manager`
`gphoto2: no camera`	Replug USB, try `gphoto2 --reset`
`Broken pipe` in Siril	Harmless — ignore or add `2>/dev/null`
`404` on qDslrDashboard	Use USB gPhoto2 instead

12. Final Commands Summary

1. Test camera

gphoto2 --auto-detect

2. Start 2-hour shoot

~/m100_usb_2hr.sh

3. Stack with calibration

siril-cli -s m100_orion.siril 2>/dev/null

4. View

siril orion_m100_calibrated.fits

You're now a CLI astrophotographer with full calibration.
Next: Add add shutdown or email alert — just ask!

13. Deep Sky Object Targets — Best for M100 + 30s Exposures

Target	Name	Best Season	Difficulty	Notes
M42	Orion Nebula	Winter	Easy	Bright, large, perfect for beginners
M45	Pleiades	Winter	Easy	Star cluster, wide field
M31	Andromeda Galaxy	Autumn	Easy	Huge, visible to naked eye
M81/M82	Bode’s + Cigar	Spring	Medium	Galaxy pair, need dark sky
M51	Whirlpool Galaxy	Spring	Medium	Spiral arms with 2+ hours
M57	Ring Nebula	Summer	Medium	Small, needs accurate framing
M27	Dumbbell Nebula	Summer	Easy	Bright planetary nebula
M13	Hercules Cluster	Summer	Medium	Globular cluster, tight stars
M8/M20	Lagoon + Trifid	Summer	Easy	Colorful nebulae, wide field
NGC 7000	North America Nebula	Summer	Medium	Large, needs Hα filter later

Recommended First Targets (30s × 240)

Target	ISO	Aperture	Total Time	Result
M42	1600	f/2.8	2 hours	Bright core + faint wings
M31	800–1600	f/4	2 hours	Core + dust lanes
M45	800	f/3.5	1.5 hours	Blue reflection + stars

Tip: Use Stellarium (sudo apt install stellarium) to find & center targets.

Framing Guide (M100 + Kit Lens 15–45mm)

Target	Focal Length	Field of View
M42	15mm	10° × 7° (fits whole nebula)
M31	24mm	6° × 4° (core + halo)
M51	45mm	3° × 2° (tight, but detailed)

Use live view + 10x zoom to center.

Start with M42 — it’s forgiving and stunning in 2 hours.

13. Deep Sky Object Targets — Best for M100 + 30s Exposures

Target	Name	Best Season	Difficulty	Notes
M42	Orion Nebula	Winter	Easy	Bright, large, perfect for beginners
M45	Pleiades	Winter	Easy	Star cluster, wide field
M31	Andromeda Galaxy	Autumn	Easy	Huge, visible to naked eye
M81/M82	Bode’s + Cigar	Spring	Medium	Galaxy pair, need dark sky
M51	Whirlpool Galaxy	Spring	Medium	Spiral arms with 2+ hours
M57	Ring Nebula	Summer	Medium	Small, needs accurate framing
M27	Dumbbell Nebula	Summer	Easy	Bright planetary nebula
M13	Hercules Cluster	Summer	Medium	Globular cluster, tight stars
M8/M20	Lagoon + Trifid	Summer	Easy	Colorful nebulae, wide field
NGC 7000	North America Nebula	Summer	Medium	Large, needs Hα filter later

Recommended First Targets (30s × 240)

Target	ISO	Aperture	Total Time	Result
M42	1600	f/2.8	2 hours	Bright core + faint wings
M31	800–1600	f/4	2 hours	Core + dust lanes
M45	800	f/3.5	1.5 hours	Blue reflection + stars

Tip: Use Stellarium (sudo apt install stellarium) to find & center targets.

Framing Guide (M100 + Kit Lens 15–45mm)

Target	Focal Length	Field of View
M42	15mm	10° × 7° (fits whole nebula)
M31	24mm	6° × 4° (core + halo)
M51	45mm	3° × 2° (tight, but detailed)

Use live view + 10x zoom to center.

Start with M42 — it’s forgiving and stunning in 2 hours.

14. M42 (Orion Nebula) — Full Add-On Guide

Why M42?

Brightest nebula in sky — visible even in light pollution
Huge — fits perfectly in M100’s wide field
Forgiving — shows detail in just 1–2 hours

Camera Settings (M100)

Setting	Value
Mode	Manual (M)
Shutter	Bulb (30 sec)
ISO	1600
Aperture	f/2.8 or widest
White Balance	Daylight (5500K)
Drive	Remote (USB or app)
Image Format	RAW (.CR2)
Lens	15–45mm @ 15mm

Step-by-Step Shoot Plan

Find Orion’s Belt → Look down → M42 is the "sword"
Use Stellarium: Search "M42" → Center → Match view
Frame: Trapezium stars in center, nebula filling frame
Focus: Live View 10x → Bright star → Manual focus
Run script: ~/m100_usb_2hr.sh
After: Shoot calibration frames (darks/flats/bias)

Expected Result (2 Hours)

Stack	What You’ll See
No calibration	Bright core, some glow
With calibration	Pink/purple wings, dark dust lanes, Trapezium stars sharp

Siril Script for M42 (Calibrated)

cat > ~/m42_orion.siril << 'EOF'
load lights/*.CR2
preprocess -dark=darks/*.CR2 -flat=flats/*.CR2 -bias=bias/*.CR2 -cfa
register
stack avg
save m42_calibrated
quit
EOF

siril-cli -s ~/m42_orion.siril 2>/dev/null
siril m42_calibrated.fits

Pro Tips for M42

Light pollution? Still works — core punches through
Moon out? Avoid full moon
Add later: Hα clip filter = deeper red

M42 = Your first “wow” image. Shoot it tonight.

Canon EOS M100 - SteveJustin1963/Telescope-Tec1 GitHub Wiki

Astrophotography with Canon EOS M100 & Linux (Lubuntu) — Full CLI Guide

1. Overview: What You Need

2. File Formats & Siril

FITS vs CR2

3. Folder Structure

4. CALIBRATION FRAMES GUIDE — Why & How

Step-by-Step: Shoot Calibration Frames

1. Darks (After Lights — Same Temp!)

2. Flats (Same Session, Same Focus)

3. Bias (Any Time)

Copy to Folders (CLI)

After plugging camera

5. USB Tethering with gphoto2 (Recommended)

Install

Test Detection

2-Hour Shoot Script (240 × 30s)

Run

6. FULL CALIBRATION + STACK in Siril (CLI)

Run stacking with calibration

View Result

7. SD Card & Write Speed

8. Power for 2+ Hours

9. WiFi Alternative (Not Recommended)

10. Test with Sample FITS (Already Downloaded)

11. Troubleshooting

12. Final Commands Summary

1. Test camera

2. Start 2-hour shoot

3. Stack with calibration

4. View

13. Deep Sky Object Targets — Best for M100 + 30s Exposures

Recommended First Targets (30s × 240)

Framing Guide (M100 + Kit Lens 15–45mm)

13. Deep Sky Object Targets — Best for M100 + 30s Exposures

Recommended First Targets (30s × 240)

Framing Guide (M100 + Kit Lens 15–45mm)

14. M42 (Orion Nebula) — Full Add-On Guide

Why M42?

Camera Settings (M100)

Step-by-Step Shoot Plan

Expected Result (2 Hours)

Siril Script for M42 (Calibrated)

Pro Tips for M42

5. USB Tethering with `gphoto2` (Recommended)