Photographer's Reckoner
Reckonersweight 1reckoner · computes, doesn't store
Photography is the art of light and the arithmetic of stops, and out in the field the arithmetic part has terrible timing. The Photographer's Reckoner does the exposure maths — the trades between the settings that decide what your sensor sees — while the light you are trying to catch is still there. It computes and stores nothing; the only record of the evening is the photograph.
This is not a screenshot. It's the real tool, running right here — go on, put something in it.
Open the demo full-screen: /demos/photographers-reckoner.html
Questions people ask
What does a photography exposure calculator actually do?
It does the stop arithmetic between your settings, so when one side of the exposure changes you know exactly what the other side must do. The maths you can do slowly at a desk, it does instantly on a hillside.
Does it work in the field with no phone signal?
That is its natural habitat. It is one HTML file running offline in your browser — it computes on the spot, stores nothing, and never needs a connection. Nothing you calculate leaves the page.
Who is the Photographer's Reckoner for?
Film shooters, long-exposure landscape people, and anyone who works in manual and would rather trust arithmetic than luck. If your camera does everything for you, you may never need it; if it does not, you will.
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