Enrico Marega Interactive photography course
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Shutter speeds and Auto ISO

A blurred photo can’t be rescued. The right shutter speed depends on how fast the subject is moving, and Auto ISO with a minimum shutter speed helps you never drop below the threshold.

1Simulator

The speed for every subject

Choose the subject, from people to animals to cars, and change the shutter speed. When the trail disappears, you’ve found the minimum speed.

2Simulator

Auto ISO with a minimum shutter speed

Choose the minimum shutter speed and lower the light. As long as it can, the camera holds the shutter speed and raises the ISO (phase 1); when the ISO reaches its maximum, it starts slowing the shutter speed (phase 2). Try Auto with full frame and APS-C too.

The table to keep in mind

1Simulator Still portrait: at least 1/125. Person walking: 1/250. Cat walking and children playing: 1/500. Person running and bicycle: 1/1000. Dog running, bird in flight, cars and motorbikes: 1/2000 and faster. These are starting values: the closer or bigger the subject is in the frame, the faster the shutter speed you need. With birds the wings move much faster than the body: for small ones you go up to 1/4000.

2Simulator Then there’s the shake of your own hand. A practical rule: handheld, use a shutter speed of at least 1 divided by the equivalent focal length. With a 50 mm on full frame at least 1/50; on APS-C the same 50 mm frames like a 75 mm, so at least 1/80. Image stabilisation (VR on Nikon, IS on Canon, SteadyShot on Sony, IBIS on Fujifilm, SR on Ricoh) gains you a few stops, but only against your own shake, not against the subject’s movement.

Auto ISO with a minimum shutter speed, in plain words

2Simulator With Auto ISO you choose two things: the minimum shutter speed, that is the slowest speed you’ll accept (for example 1/250 for people walking), and the maximum ISO, that is how much grain you’re willing to put up with. The camera takes care of the rest.

2Simulator With plenty of light it uses the lowest ISO and an even faster shutter speed. When the light drops it works in two phases, as in the diagram: phase 1, once it reaches the minimum shutter speed it holds it and raises the ISO; phase 2, once it reaches the maximum ISO it can’t raise it any further and starts slowing the shutter speed. From there on you risk blur.

2Simulator Where to set it: on Nikon in Auto ISO sensitivity control, under Minimum shutter speed; on Canon under Min. shutter spd.; on Sony in ISO AUTO Min. SS; on Fujifilm and Ricoh in the Auto ISO settings, under the minimum shutter speed item. Nikon, Canon, Sony and Fujifilm also have an Auto option: the minimum shutter speed follows the focal length, roughly 1 divided by the equivalent focal length, so on APS-C it gets faster.

Key points

  • The minimum shutter speed depends on the subject: 1/250 for someone walking, 1/1000 for someone running.
  • Handheld, don’t go slower than 1 / focal length (with stabilisation you can go a little slower).
  • Auto ISO with a minimum shutter speed: as long as it can, the camera keeps the speed you chose and raises the ISO; only when it reaches the maximum ISO does it slow the shutter speed.

Try it yourself

Set Auto ISO with a minimum shutter speed of 1/250 and a limit of 6400. Photograph people walking at sunset and watch the ISO climb as the light fades.

Post the result and tag me @enrico.marega, or send it to me by DM: I’d love to see how you tackled it.

Quick check

You’re photographing a friend running. What minimum shutter speed do you choose?
You want to photograph a seagull in flight with sharp wings. Which shutter speed do you choose?
Auto ISO, minimum shutter speed 1/250, maximum ISO 3200. The light drops and the ISO is already at 3200. What does the camera do?