Getting Started with Astrophotography: A Beginner's Guide
Are you fascinated by the night sky and want to capture its beauty through your camera lens? Welcome to the exciting world of astrophotography! In this guide, I'll walk you through everything you need to know to start your journey, using my personal setup as an example.
Essential Equipment
Let's begin with the setup I use, but this doesn’t mean you need this to be successful. You can capture beautiful photos with much more affordable setups. Because I have been a travel photographer for 15+ years, I have accumulated this equipment over that time.
Camera Body: Sony A7III This full-frame mirrorless camera is perfect for astrophotography thanks to its excellent low-light performance and high dynamic range. The BSI CMOS sensor performs exceptionally well at high ISOs, which is crucial for night photography.
Lens: Sony 100-400mm G Master This versatile telephoto zoom lens is ideal for capturing detailed shots of celestial objects. Its excellent sharpness and zoom range allow you to photograph everything from wide-field Milky Way shots at 100mm to detailed moon photos at 400mm.
Mount: Sky-Watcher Adventurer GTI This star tracker is a game-changer for deep-sky astrophotography. It compensates for Earth's rotation, allowing for longer exposures without star trails. This blog will cover a high level setup with the camera, but you can find more information on the mount here.
This is my current setup!
Camera Settings for Success
Basic Settings to Start With:
Shooting Mode: Manual (M)
File Format: RAW
Focus Mode: Manual Focus
White Balance: 3500K-4500K (adjust based on light pollution)
ISO: Start at 1600-3200
Aperture: As wide as your lens allows (lowest f-number)
Advanced Settings for the Sony A7III:
Long Exposure Noise Reduction: OFF (we'll handle this in post-processing)
High ISO Noise Reduction: Normal or Low
Bright Monitoring: ON (helps compose in extremely dark conditions)
Custom Button Setup: Assign focus magnifier to a convenient button for precise focusing
Step-by-Step Shooting Process
1. Location and Timing
Use apps like Stellarium or PhotoPills to plan your shoot
Check weather forecasts for clear skies
Consider moon phases (new moon is best for deep-sky objects)
Find dark sky locations away from light pollution
2. Setting Up Your Equipment
Mount the Sky-Watcher Adventurer GTI on a sturdy tripod
Perform polar alignment using the mount's built-in polar scope
Balance your camera and lens setup on the mount
Enable tracking at sidereal rate
3. Focusing Techniques
Switch to manual focus
Use focus magnification (custom button)
Find a bright star
Adjust until the star appears as a sharp point
Use the bahtinov mask for precise focus (recommended accessory)
4. Exposure Planning
For the Sony A7III and 100-400mm lens:
Wide-field (100mm):
30-60 second exposures
ISO 1600-3200
f/5.6 or wider
Telephoto (400mm):
15-30 second exposures
ISO 3200-6400
f/5.6-f/8
5. Taking Multiple Exposures
Shoot 20-30 light frames
Don't forget calibration frames:
Dark frames (same settings, lens cap on)
Bias frames (fastest shutter speed, lens cap on)
Flat frames (evenly lit white surface)
Understanding Calibration Frames
Calibration frames are essential for producing clean, high-quality astrophotos. Each type serves a specific purpose in removing different kinds of noise and artifacts from your images. Let's break down each type:
Dark Frames
What they are: Images taken with the same settings as your light frames (main images) but with the lens cap on
Purpose: Remove thermal noise and hot pixels
How to take them:
Use identical settings to your light frames (ISO, exposure time, temperature)
Keep the lens cap on
Take at least 15-20 frames
Ideally shoot these immediately after your light frames so the camera temperature is similar
Pro tip for Sony A7III: The sensor tends to heat up during long exposures, so dark frames are particularly important for exposures longer than 1 minute
Bias Frames
What they are: Super short exposures with the lens cap on
Purpose: Remove read noise from the camera's sensor
How to take them:
Use the same ISO as your light frames
Set the fastest possible shutter speed (usually 1/4000 or 1/8000)
Keep the lens cap on
Take 30-50 frames
Temperature doesn't matter for bias frames
Note: Bias frames only need to be taken once for each ISO setting you commonly use
Flat Frames
What they are: Images of an evenly illuminated white surface
Purpose: Remove vignetting, dust spots, and uneven field illumination
How to take them:
Use the same focus and aperture settings as your light frames
Point camera at an evenly lit white surface (light panel or white t-shirt stretched over lens)
Adjust exposure to achieve histogram peak in middle (not overexposed)
Take 15-20 frames
Important for your 100-400mm: Take new flats whenever you change focal length
DIY Flat Field Method:
Stretch a white t-shirt over your lens
Point the camera at the sky during blue hour or at a light panel
Use Aperture Priority mode (A) to start
Check histogram and adjust if needed
Flat Dark Frames (Optional)
What they are: Dark frames for your flat frames
Purpose: Remove noise from flat frames
How to take them:
Use identical settings to your flat frames
Keep the lens cap on
Take the same number as your flat frames
Tips for Processing Calibration Frames
Organization:
Create separate folders for each type of calibration frame
Label with date, temperature, and settings used
Keep master calibration frames for future use
Stacking Order in DeepSkyStacker:
Load light frames first
Add dark frames
Add flat frames
Add bias frames
Add flat darks (if using)
Temperature Considerations:
Dark frames should be within 5°C of light frames
For the Sony A7III, pay special attention to sensor temperature during summer nights
Time-Saving Strategies:
Create a library of bias frames at different ISO values
Take dark frames during cloudy nights
Make flat frames part of your tear-down routine
Common Calibration Frame Mistakes to Avoid
Using old dark frames from different temperatures
Taking flat frames with auto-focus enabled
Overexposing flat frames
Forgetting to maintain the same focus position when taking flats
Using different camera settings between lights and calibration frames
Post-Processing Workflow
This is the Orion Nebula after I have stacked 30 photos. This is just the starting point, I am hoping to capture more frames to bring out more detail into the nebula.
Stack Images
Use DeepSkyStacker or Sequator
Include calibration frames
Align and stack light frames
Process in Photoshop or Similar
Stretch the histogram
Adjust levels and curves
Remove light pollution gradients
Fine-tune color balance
Reduce noise selectively
Common Challenges and Solutions
Star Trails
Problem: Elongated stars in your images
Solution:
Check polar alignment
Verify mount balance
Reduce exposure time
Use the NPF rule for exposure times
Focus Issues
Problem: Blurry or bloated stars
Solution:
Use live view at 10x magnification
Focus on bright stars
Mark infinity focus position on lens
Consider using a bahtinov mask
M31 - Andromeda Galaxy. This is my first successful attempt only 2 months ago, and this is far better than my photos looked 2 months prior. It’s a very challenging craft but so rewarding when you can capture it!
Light Pollution
Problem: Orange/yellow sky glow
Solution:
Use light pollution filters
Shoot from darker locations
Learn to remove color cast in post-processing
Next Steps
As you grow comfortable with this setup, consider:
Adding specialized filters (narrowband)
Upgrading to dedicated astronomy cameras
Exploring autoguiding options
Learning advanced processing techniques
Conclusion
Astrophotography is a rewarding hobby that combines technical skill with artistic vision. Start with simple targets like the Moon and bright constellations, then gradually move to more challenging deep-sky objects as your skills improve. Remember, every experienced astrophotographer started exactly where you are now.
Don't get discouraged if your first images aren't perfect - focus on learning one aspect at a time, and most importantly, enjoy the process of capturing the wonders of the night sky!
Clear skies and happy shooting!