# Twilight Seizures



## Metryq (Nov 28, 2011)

For some people, the fact that it's a _Twilight_ movie would be enough:

*'Breaking Dawn' Birth Scene's Seizure-Inducing Effects*



> Reports of the 'Breaking Dawn' birth scene spurring seizures in Twilight fans have landed photosensitive epilepsy in the spotlight.
> 
> Not since the Pokemon incident of 1997, in which more than 700 Japanese cartoon viewers were hospitalized, have strobe-light-induced seizures garnered so much attention.



I have a movie lighting textbook that warns about strobe-induced seizures (figuring the frame rate of the camera and the use of strobes on a set.) Apparently, not all filmmakers are aware of it.


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## purple_kathryn (Nov 28, 2011)

hmm you would've thought someone would've known


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## Starbeast (Nov 29, 2011)

I never wanted to see the movie in the first place, but who wants to see someone giving birth with a strobe light effect?


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## odangutan (Nov 29, 2011)

Watching Twilight would give me seizures even without the strobes.


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## purple_kathryn (Nov 29, 2011)

Starbeast said:


> I never wanted to see the movie in the first place, but who wants to see someone giving birth with a strobe light effect?


 
Oh it's the only way to give birth surely!


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## Perpetual Man (Nov 29, 2011)

Cool. (That might sound odd, but now I've got the perfect excuse not to watch the thing with Mrs Perp.)


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## Ursa major (Nov 29, 2011)

Starbeast said:


> I never wanted to see the movie in the first place, but who wants to see someone giving birth with a strobe light effect?


Slightly off-topic, but strobe effects can be quite powerful in the theatre. About thirty years ago, I saw Theatr Clwyd's touring version of _The Hitchhiker's Guide to the Galaxy._

To recreate the scene where the Ravenous Bugblatter Beast of Traal appears, they inflated a giant plastic octopus, under strobe lighting. The haphazard movement of the body and arms of the inflating octopus were made to look jerky and menacing by that lighting. An excellent effect. (I don't recall, but I hope and assume they warned about the strobe lighting before people bought tickets/entered the auditorium.)


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## Metryq (Nov 29, 2011)

According to the _Professional Lighting Handbook_ by Verne and Sylvia Carlson (Focal Press):



> Care must always be taken that the stroboscopic unit, whether used for film or video, is not pulsed at less than 30 pps (pulses per second). A warning is appropriate on all stages: At that pulsation rate, one who is susceptible to epilespsy is liable to set up a sympathetic brain-wave response and go into convulsions.



The trick of course is to make sure that timing of the pulses does not set up an erratic mis-match with the frames of the recording medium. (Perhaps this is what happened in the _Twilight_ movie.) The book also notes: "beyond 60 pps, the strobe light appears as a steady light." This dovetails with Doug Trumbull's experiments during the development of ShowScan. 

Since film runs at 24 frames-per-second, that would actually be below the 30 pps threshold and be within the "danger zone." However, cine film projectors have a kind of "fan blade" arrangement in front of the gate, so that each frame is really flashed about three times. This raises the pps rate to 72 to smooth out the visible flicker.

Since I grew up in the US, I grew accustomed to NTSC video, which is 30 frames/60 fields per second. The first time I saw PAL, the system used in the UK, I knew I would never have pursued a career in video if I had grown up in the UK. PAL has a slower 25 frames/50 fields per second rate. But the kicker is the "phase alternation line" (PAL) color system. Whites and other bright areas literally "buzz" rapidly between red and blue. Makes my eyes hurt.


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## alchemist (Nov 29, 2011)

purple_kathryn said:


> hmm you would've thought someone would've known



Maybe they did. Maybe...they...did...


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## Starbeast (Nov 29, 2011)

Ursa major said:


> Slightly off-topic, but strobe effects can be quite powerful in the theatre.


 
I know it does work in theaters and in movies. For example, in the original _ALIEN _film, near the end, Lt. Ripley spots the alien around a corner and she is so terrified that she slides along the wall as a warning light is in strobe mode. Cool scene.


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## Cayal (Nov 29, 2011)

alchemist said:


> Maybe they did. Maybe...they...did...



Plot to destroy all Twi-hards?


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