What is the golden rule of shutter speed?
Handheld, keep the shutter speed at or above one divided by your focal length. On a 50mm lens that means 1/50 or faster. On a tripod the rule does not apply at all.
Also called the reciprocal rule. Shooting a 50mm lens, stay at 1/50 second or faster. On 100mm, stay at 1/100 or faster. On 200mm, 1/200.
**Why focal length.** A longer lens magnifies the scene, and it magnifies your hand movement along with it. The same small shake that is invisible at 24mm is obvious at 200mm, so the longer the lens the faster you have to be.
**The crop sensor adjustment.** On an APS-C camera, multiply the focal length by roughly 1.5 first. A 50mm lens on APS-C behaves like 75mm, so aim for 1/75 rather than 1/50.
**Stabilisation changes it.** In body or lens stabilisation buys you several stops, so a stabilised 100mm might hold at 1/15. It steadies the camera, not the subject, so it does nothing for anything that is moving.
**It is a floor, not a target.** The rule prevents visible shake at normal viewing size. Examined at full resolution, images at exactly the reciprocal often still show softness. If sharpness matters, go a stop or two faster.
## Why it barely matters in product photography
The rule exists to solve handheld camera shake. Product photography is shot on a tripod, so there is no shake to solve and the rule stops applying entirely.
That is genuinely liberating and most people setting up a studio do not realise it. On a tripod with a still product you can shoot at half a second, or two seconds, or ten. Which means you never need to raise ISO to keep a fast shutter, and you never need to open the aperture wider than you want. You can sit at base ISO and f/8, which is where the image quality is, and let the shutter be as slow as the exposure requires.
The two things that replace it: use a timer or remote, because pressing the shutter shakes the camera more than a slow exposure ever will, and watch for LED flicker, which is the one shutter speed problem that does exist indoors. Cheap LEDs pulse with the mains and produce banding at faster speeds. If you see it, slow down or change the lights.
Full starting settings are in product photography camera settings.