EXIF VIEWERStarting point for the sky: this shutter · ƒ/1.4–ƒ/2.8 · ISO 1600–6400 · manual focus on a bright star. Stars still trailing? Step down to the 300 rule or use a star tracker.
The full EXIF toolkit lives on your iPhone
This page shows what's inside a photo. EXIF Viewer by Fluntro goes further — view, edit, and remove metadata (including GPS geotags) right in your photo library, bulk-edit dates and locations, and share any photo with or without its EXIF. One-time purchase, no subscription. Your photos never leave your device there either.
https://apps.apple.com/us/app/exif-viewer-by-fluntro/id944118456
iPhone · iPad
500 rule — frequently asked questions
What is the 500 rule?
A rule of thumb for the longest shutter before stars visibly trail: 500 ÷ full-frame-equivalent focal length. A 20 mm lens on full frame allows ~25 s; the same lens on APS-C, ~16 s.
Why do stars trail?
Earth rotates 15° per hour, so stars drift across the frame during the exposure. Longer focal lengths magnify the drift — wide lenses buy you time.
500, 400 or 300 — which rule?
The 500 rule dates from film. High-resolution sensors reveal trailing sooner, so many shooters use 400, or the conservative 300 for pixel-peeping and large prints. All three are shown above.
What is the NPF rule?
A more rigorous formula that also accounts for aperture and pixel pitch, usually giving shorter limits. The 300 rule here approximates NPF results for common setups without needing your pixel pitch.
What settings for the Milky Way?
Wide fast lens (14–24 mm at ƒ/1.4–ƒ/2.8), the shutter from this calculator, ISO 1600–6400, manual focus on a bright star with magnified live view, solid tripod, 2-second timer.
Does crop factor change the limit?
Yes — the rule uses the equivalent focal length, so 20 mm on a 1.5× body counts as 30 mm and allows less time. The sensor selector applies it automatically.
How do I expose longer than the limit?
A star tracker rotates the camera with the sky for minutes-long exposures at low ISO — or stack many shorter frames in software to cut noise without trailing.
Can I check what settings my night photo used?
Yes — shutter, ISO, aperture and focal length live in the EXIF. Read them with the EXIF viewer, or on iPhone & iPad with the EXIF Viewer by Fluntro app.
Is my data sent anywhere?
No — everything runs in your browser, no network requests, and it works offline once loaded: useful under a dark sky with no signal.
Is this free?
Yes — free, no account. For reading your night shots' metadata on iPhone and iPad, the EXIF Viewer app is a one-time purchase.
Private by design
This tool was built so your photos never have to leave your device. Here's exactly what that means for your data.
Nothing is uploaded
Your photo is opened and read entirely inside your own browser. It is never sent to a server, stored, or shared — once this page has loaded, it even works with your connection switched off.
No account, no tracking
There is no sign-up, no advertising cookies, and no analytics watching what you do here. The only thing saved on your device is your light or dark theme preference.
Your location stays yours
If a photo contains GPS coordinates, they are shown only to you, on your screen. We never see them, and any map link opens only if you choose to click it.
Nothing to collect
Because no personal data leaves your device, there is nothing for us to collect, log, or process. The full details are in our Privacy Policy.
Metadata is read from your file exactly as it was saved and is shown “as is.” It can be missing, altered, or inaccurate — for example, timestamps depend on the camera's clock and GPS can be approximate — so please don't rely on it as proof for legal, forensic, insurance, or safety decisions. This tool is provided free and without warranty; see our Terms & Disclaimer for the details.
More free photo tools
All run in your browser — nothing is ever uploaded.
Inspect & verify
- EXIF Metadata ViewerSee every tag hidden in a photo
- Photo Privacy CheckerWhat does your photo reveal about you?
- Is This Photo Edited?Editing traces & AI markers
- What Camera Took This Photo?Identify the camera, phone & lens
- When Was This Photo Taken?Find the exact date & time
- Photo Location ViewerSee where a photo was taken
- Camera Shutter CountCheck a camera’s shutter actuations
Edit & clean
- Remove EXIF DataStrip metadata & GPS — losslessly
- Change Photo DateFix the EXIF date & time
- Add GPS to a PhotoGeotag — write a location into EXIF
- Add Copyright to a PhotoEmbed your name in the metadata
Image utilities
- Resize ImageShrink to exact pixels
- Compress ImageCut the file size, keep dimensions
- Add Watermark to a PhotoPut your name on it
Calculators
- Depth of Field CalculatorDoF & hyperfocal distance
- Golden Hour CalculatorSunrise, sunset & blue hour
- ND Filter CalculatorLong-exposure time converter
- 500 Rule CalculatorMax shutter before stars trail · you are here