# strobe

#### simchapup

##### Lighting Technician
im doing a talent show and this guy wants a strobe so instead of hooking strobes in could i do a really fast chase with just white strip lights

#### Footer

##### Senior Team
Senior Team
could you... of course... will it do the same effect... no.... if you want to do a strobe you will want to write an effect that takes the lamp to 20 or 30 percent (preheat) and then bumps it to full or close to full... as fast as possible... if you do not do the preheat it will not go as fast and is not the best thing on your lamps... if you want to true strobe slow motion look there is no replacement for the real thing....

#### soundman1024

##### Active Member
Footer4321 said:
if you want to true strobe slow motion look there is no replacement for the real thing....

I'll disagree here. The shutter on moving lights does a good job. Technically this is like a stroboscope, but it isn't a strobe light and I think it does just as good up to the speeds they can handle. I haven't seen a shutter that does 60Hz like some strobe lights can but within their range they do well.

As far as using regular lights I think it would work alright. It won't quite be a strobe, but it will definately get the point across. Go in and give it a try to see if it will be acceptable. Also keep in mind the lighting will be more of the natural color rather than the white color a strobe usually puts out.

#### Chris15

##### CBMod
CB Mods
Departed Member
soundman1024 said:
I haven't seen a shutter that does 60Hz like some strobe lights can but within their range they do well.

You have to consider the safety aspects of strobes. They can trigger epileptic seizures. If you use strobes, you should be placing notices to that effect in public view at the entrance to the theatre. In many cases, it is also printed on tickets and made available to persons before they purchase tickets, but this would not apply in the case of a talent show I do not expect. The likelihood of seizure is significantly reduced when strobes are run at or below 8Hz. Where multiple strobes are in use, they should all operate in synchronisation.

Clearly, the use of strobes at such high frequencies is asking for trouble.

#### soundman1024

##### Active Member
Indeed it is. I didn't know strobes went that high, but they do. My physics teacher used a strobe to verify the power company was sending us 60Hz through the AC so we could depend on that for our experiment. It was an expermient about waves and he was using a fish tank pump to make vibration for a string and we were changing the tension on it to find harmonics, but we used the strobe to verify 60Hz was the fundamental. Anyway it definately could mess people up because at 60Hz it almost appears to be steadily on, but it is a strain on the eyes. Warnings about strobe lights are always a good idea. Thanks for pointing that out Chris.

#### cutlunch

##### Active Member
Chris15 said:
You have to consider the safety aspects of strobes. They can trigger epileptic seizures. If you use strobes, you should be placing notices to that effect in public view at the entrance to the theatre. In many cases, it is also printed on tickets and made available to persons before they purchase tickets, but this would not apply in the case of a talent show I do not expect. The likelihood of seizure is significantly reduced when strobes are run at or below 8Hz. Where multiple strobes are in use, they should all operate in synchronisation.

Clearly, the use of strobes at such high frequencies is asking for trouble.

Good warning Chris as some people don't realise the problems strobes can cause. And as you point it's the rate of flicker that causes the problem. If I remember correctly a couple of years ago there was a cartoon in Japan that had a flicker in it which sent a lot of kids into fits.

Trying to find out what rates to avoid is hard. From looking at two national epilepsy societies websites I landed up with a range of 5 - 30Hz as been probelematical.

Other things that can be done to minimise risk is:
Only have the strobe on for a short time, also an effect if over done is boring
Make sure the strobe is not pointing directly into someones eyes. Eg Mount high with a steep angle.

Simchapup I would ask the performer why they want it. If it is essential to their act you will need to do it but if is only 'cause they think it looks cool then just use you strip light idea. Then You can explain to him setting up a genuine strobe will cause to many problems. Also once one performer has a strobe effect others will want it as well.

#### Chris15

##### CBMod
CB Mods
Departed Member
cutlunch said:
Good warning Chris as some people don't realise the problems strobes can cause.

Not a problem. I will continue to raise safety issues where they exist. In the current environment of liability etc., we cannot afford to ignore the inherent risks associated with this industry.

MHSTech said:

Is not this one of the reasons why flash photography is banned in many places? One of the other reasons that particularly applies to video cameras is that of copyright, but where flash photography is banned, it is generally to a] protect the item on display - paper etc. fades or b] ensure the safety of performers - imagine someone doing a delicate manoeuvre and gets distracted by a camera flash... Besides, a flash in a dark theatre has a certain essence of I want to kill that idiot.

#### CHScrew

##### Active Member
I would use a strobe. i just don't think that a fast chase looks as good. Plus, it's not very goos for the lights. On my board, if you turn the chase all the way up for too long it will short... But that's just me.

#### PATech

##### Member
Chris15 said:
Clearly, the use of strobes at such high frequencies is asking for trouble.

Thank you very much Chris for bringing this up. Last summer I worked as a tech at a major corporate theme park (which will remain nameless as I am going back to work there this summer.) One of the shows that I was running had a substantial moving light rig and several cues in which most of the movers strobed. During one show a very young audience member with epilepsy suffered from a seizure despite the warnings posted at the door about the use of strobe effects in the show. Why his parents took him into the theatre is still a mystery to me. This is a serious concern that can cause a life-threatening medical emergency for a small percentage of the show-gowing population. Keep that in mind, because I can attest that it is not pleasant to have a 5-year-old kid seizing in the middle of your venue.

--PATech

#### cutlunch

##### Active Member
PATech said:
Thank you very much Chris for bringing this up. Last summer I worked as a tech at a major corporate theme park (which will remain nameless as I am going back to work there this summer.) One of the shows that I was running had a substantial moving light rig and several cues in which most of the movers strobed. During one show a very young audience member with epilepsy suffered from a seizure despite the warnings posted at the door about the use of strobe effects in the show. Why his parents took him into the theatre is still a mystery to me. This is a serious concern that can cause a life-threatening medical emergency for a small percentage of the show-gowing population. Keep that in mind, because I can attest that it is not pleasant to have a 5-year-old kid seizing in the middle of your venue.

--PATech

Only some Epileptics are photo-sensitive. Being only Five years old this may never have happened to the child before. It could also be that the sheer volume of the strobe effect overwhelmed him where he may have been to other shows with lesser strobes with no problems.

ya...all this true... But to be honest, putting two of those 10$cheapy strobes that you can pick up at the party store right behind the drummer on a dark stage is a perfectly fine thing...cheap and easy. run those, then putting some white blinders in front on top of what ever your hanging is simple and well used and proven...and for blinders you can go to home depot and find lighting stings of like 10 fixtures in a standard outlet that run for like 15$ Why get complicated?...it all looks just as good if you really know how to run it