Epilepsy?

[#1]

A few days ago I went to a restaurant with a family group for dinner.
At one end of the room was a Christmas tree with twinkling lights.
A family member took the young ones in our group, arranged them at the foot of the tree and started taking photos of them.
A lady sitting at a table near the tree asked the family member to turn off the camera flash.
Apparently someone else at her table was being affected by the flash and was shielding her eyes and shaking.
I had never personally come across this before but understood the situation and the photography stopped.

[#2]

I used to live with Epileptics at College years ago, the staff wouldn't even take them to the Pub on Disco night for fear of the Disco lights causing them to have seizures.

[#3]

My mother has never suffered from epilepsy but flashing lights would frequently trigger a migraine.
Frequently, prior to a news item or even a pop video, it would be announced that the item contains flash photography so sufferers could change channels.

[#4]

I'm always watching WWE on Sky, and they're always warning that they use flashing lights etc, as they use Pyrotechnics in the wrestlers' entrances etc.

[#5]

Flash bulbs are a problem for epileptics and all TV news/current affairs programmes will warn viewers if there is flash photography in the item.

[#6]

I haven't seen a flash bulb for years - I even remember using them 

[#7]

Most modern cameras still use them, even some phone cameras.

[#8]

Quote from: Oldjim

I haven't seen a flash bulb for years - I even remember using them

The memories of my early photography.

[#9]

Some sufferers of epilepsy are affected by low-frequency flashing lights.

Quote

Most people with photosensitive epilepsy are sensitive to 16-25 Hz. Some people may be sensitive to rates as low as 3 Hz and as high as 60 Hz.

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Around three in every 100 people with epilepsy have photosensitive epilepsy.

(According to Epilepsy Action https://www.epilepsy.org.uk/ ).
That figure seems rather low to me.

[#10]

I've never really had a problem with flashing lights / cameras but i've known people who have. Heck, my girl can't even do 360 round a roundabout without getting dizzy 

[#11]

Quote from: 7up

Heck, my girl can't even do 360 round a roundabout without getting dizzy

Tell me about it. SWMBO is exactly the same

[#12]

Quote from: vilefoxdemonofdoom

Some people may be sensitive to rates as low as 3 Hz

Flash guns used to fire a single burst but the flash in modern cameras can fire a short series of flashes possibly around 3 per second so I can see how people sensitive as mentioned about would be affected.

[#13]

Quote from: Strat

...but the flash in modern cameras can fire a short series of flashes possibly around 3 per second...

I've often wondered why they do that? Even in daylight I've seen the light flicker when the shutter button is just partly pressed.

[#14]

It's usually for red-eye reduction as the first flash causes the iris in the eye to reduce in size thus minimising red reflection from the back of the eye.
Other 'pre-flashes' are used by the autofocus.

[#15]

Thanks for the explanation