Astro Photography Calculator
Exposure & ISO Calculator
Your Settings
Exposure
1.0s
ISO
Aperture
f/2.8
Star Trailing
0.3px
Equipment
Select a camera first to see compatible lenses
Stable but subject to Earth rotation
Target Object
✓ = visible now from your location
0° = equator (fast motion), ±90° = poles (slow motion)
Location
Best Dark Sky Nights
Next 14 days ranked for astrophotography
Next Best Night
13 days
Fri, Feb 6
Fri, Feb 6
Moderate moonlight
53%
dark
Thu, Feb 5
Moderate moonlight
49%
dark
Wed, Feb 4
Moderate moonlight
45%
dark
Tue, Feb 3
Moderate moonlight
43%
dark
Mon, Feb 2
Moderate moonlight
41%
dark
How It Works
⏱️ Exposure Time
NPF rule calculates max exposure before star trailing, based on your sensor's pixel size, focal length, and target position.
🔭 Why Declination Matters
Objects near the celestial poles move slowly (longer exposures OK). Objects near the equator move fastest (shorter exposures needed).
🌙 Moon Data
Moon phases use IAU astronomical constants (Meeus algorithms). No API needed - pure math works for any date, past or future.
How It Works
⏱️ Exposure Time
NPF rule calculates max exposure before star trailing, based on your sensor's pixel size, focal length, and target position.
🔭 Why Declination Matters
Objects near the celestial poles move slowly (longer exposures OK). Objects near the equator move fastest (shorter exposures needed).
🌙 Moon Data
Moon phases use IAU astronomical constants (Meeus algorithms). No API needed - pure math works for any date, past or future.