Silverlog Stars
Astrophotography Exposure Calc
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
Calculate the longest exposure for sharp stars at any focal length. Avoid star trails with the 500 Rule, NPF Rule and more.
Silverlog Stars calculates the maximum exposure time for sharp, pinpoint stars — helping you avoid unwanted star trails in astrophotography.
HOW IT WORKS
Choose your focal length, aperture and camera sensor size. The calculator shows your maximum shutter speed using an established rule (500 Rule, 400 Rule or NPF Rule) so stars remain points of light rather than streaks.
FEATURES
• 500 Rule and the more conservative 400 Rule
• NPF Rule calculation (more accurate for modern sensors)
• Seven digital sensor sizes, from 1-inch to medium format
• Typical pixel pitch built in for each sensor size, used for NPF results
• Star trail mode — see how long your trails will be for a given exposure time
• Tonight's moon phase, plus Milky Way visibility for the current month (Northern Hemisphere)
• Works offline — no internet connection needed
• Clean, focused interface
• Dark mode support
USEFUL FOR
• Milky Way photography
• Nightscape and starscape shooting
• Choosing the right focal length for astrophotography
• Understanding the relationship between focal length and star movement
• Planning intentional star trail exposures
Part of the Silverlog photography toolkit. No account required. No data collected.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Updated for iOS 27, with the latest version of the app's frameworks. Everything works as before.
The developer, Simon Westgate, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Simon Westgate
- Size
- 42.2 MB
- Category
- Photo & Video
- Compatibility
Requires iOS 16.4 or later.
- iPhone
Requires iOS 16.4 or later. - iPad
Requires iPadOS 16.4 or later. - Mac
Requires macOS 12.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Actual Saint $29.99
- Guardian Angel $9.99
- Absolute Hero $4.99
- Nice One $0.99
- Legend $2.99
- Copyright
- © SilverLog 2026