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Cell Phone Screen Light As A Source

Published : 22nd February 2005

Hi All,

I am shooting this commercial in couple of weeks, in one of the shot director only wants to see cell phone screen light as a source. My question is let say if I am using 800 ASA film and the room where we are shooting is totally dark how much light is enough to do the job without making it over lit. There are three characters in that shot all of them got their own cell and its going to be three shot followed by CU.

I would love to hear your advise and suggestions and thanks in advance.

Fahan Alam
D.P (Karachi, Pakistan)


class="style9">>My question is let say if I am using 800 ASA film and the room where we >are shooting is totally dark how much light is enough to do the job >without making it over lit.

The cell phone displays are probably too low of a light level for use as a source. My guess would be that you will need to supplement the lighting. My Samsung phone doesn't emit enough light to read any footcandles at one foot distance. Maybe the screen's deep color is fooling the meter somewhat but it seems very dim.

I think your instincts are correct in trying to minimally light the talent. Because of the low light levels of cell phone displays it would seem unnatural if they were too bright in comparison to the rest of your set or location. Balancing the lighting is important in this scenario.

So, much depends on the individual shots and how much you can cheat lighting the faces from off frame. You may end up with two or three different lighting methods depending on the shot.

If the talent is not moving around you could light them low from one side off camera with traditional units. If they are moving with the phones in hand around you may need to try to build a tiny light source in the cell phone itself as long as the cell phones are positioned so that you don't see the fronts in the shot.

One time I made some very small lights from batteries and flashlight bulbs. There are many types of small lamps made for a variety of uses that can be custom built for hiding on the phone. If the shot permits you can even power the bulbs through a hidden wire on the talent to a power source elsewhere. Try researching the available bulbs and their output. You may add some blue gel and diffusion to the lamps as well.

Sounds like fun. Hope this helps.

BTW-I'm curious how much production happens in Pakistan. I may be travelling to Islamabad in the fall and may need some advice and guidance on shooting there.

Jim Sofranko
NY/DP



If it's a Treo commercial you might not have any trouble.

As long as you don't see the screen in the shot you could tape a Kino MicroFlo to the front of the phone and dim it accordingly.

Or shoot in 16mm with Super Speeds and 7218. In theory your key only has to be 5 footcandles... but I'm not sure you'll get that out of your average cell phone.

Art Adams, DP [film|hidef|video]
Mountain View, California
San Francisco Bay Area - "Silicon Valley"
http://www.artadams.net/



>I am shooting this commercial in couple of weeks, in one of the shot >director only wants to see cell phone screen light as a source. My >question is let say if I am using 800

What about sticking some reflecting material on the screen and
lighting it with a small unit (a Dedo light, for example) up behind your heroes? In "Every Frame a Rembrandt" Andrew Laszlo describes a reflecting material by 3M that would be really useful.

http://cms.3m.com/cms/US/en/2-135/ciikFFL/view.jhtml

Borja Marcos



In "Every Frame a Rembrandt" Andrew Laszlo describes a

>reflecting material by 3M that would be really useful.

www.3m.com/scotchlite

Nick Hoffman NYCDP


>>in one of the shot director only wants to see cell phone screen light as a >source. My question is let say if I am using 800...

>>What about sticking some reflecting material on the screen and lighting >it with a small unit (a Dedo light, for example) up behind your heroes?

If you use a Gel sample pack (i.e. Rosco, GAM, etc...) you will have several different types of reflector material samples (already pre-cut to about the size of a screen). A little snot tape and you have an instant mini-reflector. (Sample packs will have soft and hard reflective material, so as DP your DP will have a choice).

Price : free from your local expendables store.

Matt Efsic
Ventura, CA
Film Student, Grip/Electric, Future DP


I've used a small florescent type (though not a fluoro) fixture used by street racers to under light their cars. These tubes come in all manner of configurations and are cheap and easily corrected for CT.

You might gut a mobile and install one of these possibly using a piece of half frost or similar to diffuse if needed.

Nick Paton
Director of Photography
High Def./Standard Def./Film
Aaton XTR Prod owner operator
Brisbane, Australia
www.npdop.com


>>I am shooting this commercial in couple of weeks, in one of the shot >director only wants to see cell phone screen light as a source.

What kind of camera angle are you dealing with? You might be able to tape or otherwise attach a mini KinoFlo to the arm that is actually holding the phone, obviously with the arm itself blocking the camera's view of the light.

Erin Harvey
L.A. cinematographer


If the effect you want is the screen - visible to camera - blowing out hot, then using retro-reflective material would work - if you put a light source on axis with the camera or use a beam-splitter to light the Scotchlite or similar material from the lens axis.

If the effect you want is light emanating from the phone and actually lighting the faces of the people around it, the retro-reflective material is not what you want to use.

Retro-reflective material sends light back exactly where it came from and no where else - you will not get a general glow that will light the actors unless you put a light behind each and every one of them as close to on axis with their faces...and even so I don't think it will read that well. even a couple of degrees off axis will greatly reduce the reflection.

I would guess that the electroluminescent material that someone is about to mention soon will not put out enough lumens to do what you want.

I recommend getting a dummy phone, taking out the guts behind the screen, putting in a piece of aluminium (or aluminium if you are working in the UK or more recent former colonies) as a reflector, mounting a couple of peanut bulbs (12 volt miniature tungsten halogen bulbs - many of which come set up to go into sockets that are virtually identical to the old AG-1 and AG-1B flash bulbs) running wires out the back and down the arm of one of the actors, and putting a piece or two of diffusion over the bulb.

You can only run a rig like this for a minute or so before the bulbs get so hot that they might melt through the diffusion, so you have to be careful on set. You also don't want to melt the shell of the phone all over the actor's hand.

My suggestions are very old-school and low tech but might work.

Note :

When I use these sorts of low voltage bulbs, I usually use two variac (adjustable autotransformer dimmers) with one plugged into the other. The first one takes the voltage down to maybe 20 volts and the second one is a "fine tuner" to set the voltage exactly where I want it. This has the effect of allowing much more fine adjustment of the voltage than if you just use one variac.

These bulbs are not very tolerant of over voltage - even if they can survive 20 per cent over voltage, that is only 2.4 volts. Better to run them a little below their design voltage than a little above – ten percent over voltage cuts the life in half and these bulbs are only good for a few hours to start.

There is no need to rent or mess with DC power supplies for this sort of thing - every lighting rental house has these autotransformer dimmers (often incorrectly referred to as rheostats) … they are known as Variac’s, Powerstats and probably several other names.

I hope this is useful info.

Mark Weingartner
VFX DP/Supervisor
Gaffer in a former life


Mark H. Weingartner wrote:

>>I recommend getting a dummy phone, taking out the guts behind the >screen, putting in a piece of aluminium (or aluminium if you are working >in the UK or more recent former colonies) as a reflector, mounting a >couple of peanut bulb

Or another thought, There is a company that makes 3 led replacement bulbs for mag lites that take 2 AA batteries. These things are pretty small and run for darn near forever on 2 AA batteries, I'm talking about 40+ hours. The output is blue flavoured but there is enough of it to send through some CTO of one flavour or another plus some diffusion and still have enough left over to light a face nearby. The blue flavour of the light might be just the right thing though.

Expanding on this idea even further , perhaps give a call to the light panels people who make these led lights that are on the market right now for incredible amounts of money. They might be able to make a custom size for you. In any case the LED option might be the way to go once you strip the insides out of a cell phone. The LED's run cooler than incandescent bulbs FWIW.

Mark Smith
DP NYC.


>>...These things are pretty small and run for darn near forever on 2 AA >batteries, I'm talking about 40+ hours.

That's what I was getting at in my original reply. There are many, many miniature low voltage lamps that can be run on a small DC battery supply.

With a little research and some ingenuity the miniature light could probably run off the cell phone battery. Props!

Jim Sofranko
NY/DP


Rig a green Nichia 5mm LED on the inside hand-side of the phone and you'll have more light that you can deal with. For that matter you can use a 5500k, 3000k, or any other color.

Walter Graff
BlueSky Media, Inc.
www.bluesky-web.com


1/. You could discreetly rig a high powered LED to the phone's faceplate.

2/. If you don't mind trashing a few phones in experimentation, gut the innards and replace with some button cell batteries and a few LEDs, put a little slice of diffusion under the faceplate and keypad. Less than $50 at Radio Shack and you could even install a dimmer to control the light level.

Ched "the film hacker" Beckwith
MFA candidate, American University
IBEW Local 1200
Washington, DC
http://www.starfortress.com/models.html


Mark H. Weingartner writes

>>My suggestions are very old-school and low tech but might work.

The very best sort of suggestions.

Personally I'd just rustle up a small PCB made for the task that had an array of low profile LEDs on it and was designed to stick onto the front of the phone. Camera shots from behind the actor would show a real display, while camera shots from the front would have the LED panel illuminating the actors face.

A recent project like this has been the display module in a space helmet. The CGI simulation of what the actor was supposed to be seeing was matched by a diffused RGB LED array that mimicked the CGI displays overall illumination. If the display was primarily green with a red flashing panel, then the eyepiece illumination would be green with a flashing red component. It all helps sell the story.

Clive Mitchell
http://www.bigclive.com



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