# Astro Max Calculator — Max Shutter Speed Calculator

> Max Shutter Speed Calculator (iPhone/iPad app by Gregory Wu.)

- Source: https://appshunter.io/ios/app/astro-max-calculator/id1598192808 (this page in markdown: same URL + `.md`)
- Developer: [Gregory Wu](https://appshunter.io/developer/1598192810)
- Category: Photo & Video, Utilities
- Price: Free
- Age rating: 4+
- Requires: iOS 14.1 · 0 MB
- Languages: English
- Released: 2021-12-06
- Data updated: 2026-05-17
- User reviews in markdown: https://appshunter.io/ios/app/astro-max-calculator/id1598192808/reviews.md

## What is Astro Max Calculator?

Astrophotographers often use the "500 Rule" as a way to estimate the maximum shutter speed that can be used to capture the night sky before star trailing becomes noticeable. Here is a simple calculator, in night vision friendly red (or daytime color mode), to find recommended maximum shutter speeds based on your lens focal length and digital camera sensor's crop ratio.

The 500 Rule is just a starting point for night sky astrophotography. You can try selecting a more conservative rule in the app (400, 300, etc.) for better focused shots. As always, experiment and find out what works best with your setup!

Developer Note: This is my first App Store release. Please let me know how this app works for you, how it doesn't, or what you would like to see in further updates. Thanks!


## Version history (last 2 releases)

### 1.1 — 2021-12-13

- Added a Day Mode color scheme.
- Fixed a bug so that the lens focal length will update if it exceeds a new selected upper limit.
- Slight updates to the user interface.
- Added crop factor information for Micro 4/3 cameras.

### 1.0 — 2021-12-06

No release notes.

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## More apps by Gregory Wu

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All apps by Gregory Wu: https://appshunter.io/developer/1598192810

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-05-17.*