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Strobe flash on S16


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#1 Andy Karkut

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Posted 10 October 2009 - 01:53 AM

Set up: a guy is having his photograph taken in a photo booth.

I need to create the effect of the strobe flashes.

(Being able to control the duration of the strobe flash is a must.)

At the moment, we are considering the following, none of which I have any experience with...so your thoughts/suggestions would be greatly appreciated.

We're shooting S16 on the SR3.

-Atomic 3000
-Unilux H3000

Anything else you would recommend?

Thank you.
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#2 John Sprung

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Posted 10 October 2009 - 01:05 PM

You can probably shoot with whatever strobe is there, and cut together the ones that work. Remember that if you see the strobe flash in the viewfinder, it *didn't* go on the film, and vice versa.




-- J.S.
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#3 Andy Karkut

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Posted 10 October 2009 - 03:04 PM

Thanks, John. Unfortunately, we cannot 'cut' anything together because the whole thing is one take/one shot, there is no cut -- the guy is basically talking to the camera while the strobe flashes go off simultaneously.

I am looking for specific feedback on the above strobe models, that is if any of you gentleman have tried it (which I am sure a number of you would have had).

Any thoughts?
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#4 Andy Karkut

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Posted 14 October 2009 - 11:44 PM

Would anybody know if I can sync a strobe to a SR3?

The scene I'm shooting takes place in a photo booth, and requires the effect of an old-fashioned camera strobe -- the flash goes off and it "holds" on the actor for a second.

Should I set the frame rate to *more* than 1/48th; say 1/60th? Or should I simply sync strobe with 24fps camera speed?

Please help!
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#5 K Borowski

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Posted 15 October 2009 - 08:17 AM

Would anybody know if I can sync a strobe to a SR3?

The scene I'm shooting takes place in a photo booth, and requires the effect of an old-fashioned camera strobe -- the flash goes off and it "holds" on the actor for a second.

Should I set the frame rate to *more* than 1/48th; say 1/60th? Or should I simply sync strobe with 24fps camera speed?

Please help!


For an "old" strobe, are you talking about flashbulbs?

I am not an expert, but I think most electronic flashes are extremely short durations, between hundredths and thousandths of a second in duration.

Of course, if you cannot get flashbulbs you can "fake" the effect using a movie light and some sort of improvised shutter or by just switching it on and off.


As for lessening the frame rate, NO you do not want to do that because it will increase the chances of you missing the flash when it goes off.

You are saying conflicting things in your posts. You are talking about a high speed flash earlier, but now it seems like you want a longer duration. . .

Perhaps a more concise and detailed description of what you want would help us help you.

Also, do you want the frame to be dark or nearly dark between flashes, or do you want a normally-lit shot whited out each time the flash goes off?
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#6 Andy Karkut

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Posted 15 October 2009 - 04:52 PM

Apologies about the confusion. I do appreciate the time of members here.

Here's what I'm after, so your input will help tremendously. Thank you.

The set-up:
- The scene takes place in a confined space: a booth
- Actor is looking directly into camera
- A *single* flash goes off every 5 secs (flash comes from offscreen) -- mimicking the effect of an old photography camera flash
- Between flashes, the frame will be normally lit w/soft light ie, it will NOT be dark.
- Camera: Arri SR3, running at 24fps with 180 degree shutter
- Planning to use the Atomic 3000 DMX strobe light

Goal:
- Want every single flash from the strobe to register on film

Questions:
1) Do I sync the strobe with the camera, then let both run as they may?
2) If not the above, then do I set the *speed*/duration on the strobe light to be slower than the camera ie, 1/24th of sec on strobe and let the camera run normally at 1/48th of a sec?
3) Do I expose to the normally lit interior and then let the strobe flash goes 1 to 3 stops over? Or do I expose to the flash?
4) Lastly, how do I meter the strobe? I have a Sekonic digital light meter.
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#7 Andy Karkut

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Posted 17 October 2009 - 06:07 PM

Maybe I scared everyone off.
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#8 Mei Lewis

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Posted 26 November 2009 - 11:19 AM

Have you shot this yet?
How did you do it?
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#9 Tushar kanti ray

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Posted 26 November 2009 - 12:10 PM

Have you shot this yet?
How did you do it?

I suggeste u should not expose for any, that means the soft light that is already there should be 1-1 1/2 stop under and then the flash light should be 1 stop over. Now about the flash, I think u can use a 1k fresnel with single layer of 216 diffusion near the camera and switch it on an off at the speed required.
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#10 Chris Keth

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Posted 26 November 2009 - 05:31 PM

I suggeste u should not expose for any, that means the soft light that is already there should be 1-1 1/2 stop under and then the flash light should be 1 stop over. Now about the flash, I think u can use a 1k fresnel with single layer of 216 diffusion near the camera and switch it on an off at the speed required.


Sorry but that won't look like a photographic strobe. It will look like a light turning on and off. I have shot with strobes before and I never had a problem getting them on film. I used one for a gunshot effect and we did 3 or 4 takes and got all the takes on film with flashes. Use a strobe unit that allows you to turn the strobe duration down as low and possible. If you're really worried about it going on film every time, you could use 2 strobe heads and 2 power packs and have one person trigger them by hand at the same time. To the eye, it will come off as one strobe pop. In reality, it may stagger the strobes just enough to help ensure at least one gets on film.

The alternative is to create the look in post with very fast, very drastic brightness changes. It's very easy to make it look good. Since it's a very, very short duration nobody really gets a good look at it.
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#11 David Rakoczy

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Posted 26 November 2009 - 07:51 PM

Chris is absolutely correct.. and Karl.... Shutters look like lightning not a 'flash'...

I have used Data Flashes.. they are cheap and easy to find and you can adjust the duration of the flash... I just set it to my eye and shot and it worked great. Here it is. Many theatrical renatl houses have them. The color temp looked very natural on Tungsten Film.
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#12 Chris Millar

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Posted 27 November 2009 - 12:44 AM

Yes you can sync a strobe or flash with a camera.

I've done this.

You'll need two things however:

Some sort of output from the camera - if it doesn't have a sync out then some sort of mechanical thing that moves in sync with the shutter like an inching knob etc...

A strobe or photographic flash with an input - some DMX strobes dont have these - forget DMX, it can only define speed but not phase which is what we need.

5 secs is good - its means you can forget your Atomic and get an actual photographic flash like a Metz or hire something with more output - it should charge up again in time.

Firstly, I need to know ... are you electronically minded ? does op-amp or comparator mean much to you ? Keen to learn ?

You might also want to take note that the effect isn't usually that great once the amount of work put into it is compared to the output of doing it in post.
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#13 Doug Brantner

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Posted 23 March 2010 - 12:05 AM

Lightning Strikes strobes are designed specifically for film. The minimum flash duration is 1/24th of a second, so if you're shooting 24fps you can't miss it.
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#14 Chris Millar

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Posted 23 March 2010 - 12:50 AM

The minimum flash duration is 1/24th of a second


I don't know much about those units but your description goes against the grain of at least my conceptual understanding of them ...

um, so what is the 'off' time ? or in other words what is its duty cycle ? for it to be useful for 24fps it'd have to have a zero off time - in which case it's just a lamp ... :huh:
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#15 Rob Featherstone

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Posted 23 March 2010 - 06:57 AM

The think about strobes for still cameras is that they expose for exactly 1/60 th of a second you expose exactly 1 frame of film.

I shot a test on black and white reversal and when I looked at the clip there really was just one exact frame exposed by the flash.

I believe the options are to use "lightning strikes" or paparazzi flashers that available light in NY has. You can program the length of the exposure and
I believe you can either have someone randomly fire it or program a sequence.

The other option, which doesn't seem like it would work for you is to buy some vintage flash bulbs on ebay and fire them with an old camera (or sveral old cameras).

Because they are "analogue" they expose (over expose?) several frames.
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#16 Chris Millar

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Posted 23 March 2010 - 07:07 AM

The think about strobes for still cameras is that they expose for exactly 1/60 th of a second you expose exactly 1 frame of film.


You'd get an exposure if the shutter were open at the time ...

Where did you get that exact '1/60th' figure from ??

'Power' output for flashes is often not determined by how bright they are but for the duration of the burst.
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#17 Rob Featherstone

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Posted 23 March 2010 - 08:02 AM

My research was about 10 years ago so things are probably really different now!

-R




You'd get an exposure if the shutter were open at the time ...

Where did you get that exact '1/60th' figure from ??

'Power' output for flashes is often not determined by how bright they are but for the duration of the burst.


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