Photography
Shutter Speed Calculator
Enter focal length and crop factor for a reciprocal-rule shutter, or two shutter times to see stop difference.
What shutter speed should I start with?
Shutter speed is how long the camera’s sensor is exposed to light. A classic handheld starting point is the reciprocal rule: try about 1/(focal length × crop factor) seconds — so a 50 mm lens on a 1.5× crop body suggests roughly 1/75 s before considering subject motion or stabilisation. Separately, the stops mode compares two shutter times with log2(t2/t1) so you can see how many exposure stops separate them when adjusting alongside aperture or ISO. Stabilised lenses and careful bracing can go slower; action subjects often need faster. Tie framing to crop factor and sharpness depth to depth of field.
Worked example
50 mm × 1.5 crop → reciprocal 1/75 s. Shutters 1/125 s (0.008) and 1/60 s (≈0.0167) differ by about +1 stop (longer is brighter).
Limits and assumptions
Reciprocal rule ignores IBIS, VR and subject speed. Enter shutter times in seconds (1/125 ≈ 0.008).
Frequently asked questions
What is shutter speed?
Shutter speed is how long the camera lets light hit the sensor for one frame. Faster shutters (like 1/1000 s) freeze motion and let in less light; slower shutters (like 1/30 s) blur motion and let in more light.
What is the reciprocal rule?
A rule of thumb for handheld shooting: use a shutter around 1 divided by the effective focal length (lens mm × crop factor) as a starting point.
What is a “stop” between shutters?
Doubling or halving shutter time changes exposure by one stop. Positive stops in this tool mean the second shutter is longer (brighter).
Does IBIS change the rule?
Yes — in-body or lens stabilisation often lets you go several stops slower; treat reciprocal as a conservative baseline.