THE RULE
People divided by three
For groups under 20, divide the number of people by 3 in good light, or by 2 in poor light, and take that many shots for a better than 95% chance of one good one.
Count for your groupTHE MATHS OF A GROUP SHOT
Somebody
always blinks.
A blink is quick, but a group photo has a lot of eyes.
÷ 3 in good light
4–5% Share of time a typical person's eyes are blinking
- Divide the group by three
- Find better light
- Stop the chatter, then shoot
- Fewer spoilt frames
One person is rarely caught mid-blink. Add more people and the odds of a clean frame fall fast. A CSIRO physicist turned that into a rule of thumb you can use at any family gathering.
THE SHORT ANSWER
Take more frames
than you think.
Physicist Piers Barnes's rule of thumb is for groups of fewer than 20.
Light and talking both change the odds.
LIGHT
Pose in the light
In poor light the shutter stays open longer, which gives more time for someone to blink. Barnes's advice is to move the group into good light.
Set up the shot
CHATTER
Talking adds blinks
Studies put the blink rate at about 17 a minute at rest and about 26 in conversation. A group still chatting is blinking more.
See the numbersHOW MANY SHOTS?
Count the people,
then the frames.
Pick a group size. The rule gives the number of shots for a better than 95% chance of at least one with everyone's eyes open. The bar shows how many frames you need.
Rule of thumb from CSIRO physicist Piers Barnes, as reported by Live Science and Country Life.
FOUR HABITS FOR GROUP SHOTS
Fewer closed eyes,
less fuss.
None of this needs special kit. It is about stacking the odds in your favour before and during the shoot.
Count heads and set your number
Divide the group by three in good light or by two in poor light, and plan to take at least that many frames.
Move into the light
Better light lets the shutter close faster, so there is less time for anyone to be caught mid-blink.
Hush the group just before
Talking raises the blink rate. Ask everyone to settle and look at the lens before you start.
Shoot in the window after 'don't blink'
Barnes said that after you tell people not to blink, the odds are better for about 12 seconds, if you can accept a few wide eyes.
TWO NUMBERS WORTH KNOWING
A blink is short,
but it adds up.
One figure for how often one person is mid-blink,
one for how talking changes the rate.
4–5%
Share of time a typical person's eyes are blinking
Fine for a portrait of one, Barnes said, but every extra person in the frame lowers the chance of an unspoiled photo.
ONE PERSON · BARNES, CSIRO
17 vs 26
Blinks a minute: at rest vs in conversation
The rate falls to about 4 to 5 a minute during reading. Brych and colleagues found complex facial movements of speaking drive the rise.
TALKING · BRYCH ET AL. 2021
Barnes and Nic Svenson of CSIRO were awarded the 2006 Ig Nobel Prize for mathematics for this calculation, which they described in the report 'Blink-Free Photos, Guaranteed' (Velocity, June 2006).
WHY THE ODDS FALL
Every face is
another dice roll.
Barnes's calculation treats each person's blinks as separate events. The chance that one person blinks during a short exposure is small, but the chance that nobody in the group does falls with every extra person.
That is why the rule scales with the head count, and why large groups, such as a whole wedding party, are so hard to get perfect. Country Life suggests remembering that when planning wedding photos.
Questions
Questions people ask
How many photos should I take of a group?
For fewer than 20 people, CSIRO physicist Piers Barnes suggests dividing the number of people by 3 in good light, or by 2 in poor light, for a better than 95% chance of one good shot.
Why does poor light mean more blinks in photos?
In poor light the camera's shutter stays open longer, so there is more time in which someone can blink and spoil the frame.
How often do people blink?
Barnes's calculation uses 10 blinks a minute and a blink of 250 milliseconds. A 2021 study cites about 17 a minute at rest, about 26 in conversation and 4 to 5 while reading.
Can you photograph a big crowd with no one blinking?
Barnes's calculations suggest that a flawless photo of a group of 100 or more is nearly impossible, so expect to retouch or accept a few closed eyes.
Did this really win a prize?
Yes. Nic Svenson and Piers Barnes of CSIRO received the 2006 Ig Nobel Prize for mathematics for calculating how many photos you need to take.
Where the facts come from
Updated
- Live Science: Picture perfect, how to make blink-free holiday photos (interview with CSIRO physicist Piers Barnes)
- Country Life: Curious Questions, how do you take a group photo in which nobody is blinking?
- Improbable Research: In short, how to take a group photo with no blinks (2006 Ig Nobel Prize for mathematics)
- Brych M, Murali S, Händel B (2021) How the motor aspect of speaking influences the blink rate. PLOS ONE 16(10): e0258322 (PMC)