Film-Tech Forum ARCHIVE: Using Flash Camera in Booth

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Posted by David Stambaugh (Member # 1102) on 03-02-2003, 04:29 PM:

This may be a really dumb question, but is there any reason to be cautious about taking flash pictures in an operating booth? Like, are there any photo detectors that might be sensitive to a bright flash of light in the general area? I'm looking for technical issues, not common-sense stuff like the flash possibly disturbing an audience or something like that.

Posted by Ray Bernardi (Member # 1615) on 03-02-2003, 04:43 PM:

I've taken flash shots in my booth with the projector running. No audience when I did it. No issues with the camera, it didn't care. I have no light sensitive interlocks at all. They are all mechanical. The sound head didn't seem to care either. I'm using an old analog system with a white light, I took shots directly at that area and didn't notice a pop or anything in the speakers.

Posted by Steve Kraus (Member # 476) on 03-02-2003, 08:29 PM:

Not a technical issue but a few years back while attending Sho-nuff (ok, Showest) a staff girl at Caesars had a cow when I tried to photograph the Omnimax booth from outside the glass. She gave me some BS about sensors. I said I wouldn't be using a flash. She still went off in totally bovine fashion. Like there's anything secret there that you could reverse engineer from a photo taken outside the glass.

Posted by Joe Morris (Member # 1553) on 03-02-2003, 08:34 PM:

white exciters don't have a problem with excess light, but if you have the ultrajax red LED exciters...any excess light, no matter how quick will cause a pop in your sound

Posted by Mark Gulbrandsen (Member # 72) on 03-02-2003, 09:02 PM:

Just don't do flash photos of your service tech wiring up a sound rack when he's not looking....I had to pull one of my employees down off the exhaust blower when I tried that one once.
Mark

Posted by Justin West (Member # 920) on 03-02-2003, 09:25 PM:

Joe must be right, because when I was recently touring a booth with some other UDITOA members, the repeated flash photos were causing pops in the sound and Jim Goble gave us the "heads up" as to why. [Confused]

Posted by Darryl Spicer (Member # 711) on 03-02-2003, 09:31 PM:

white or red it does not matter you get extranious light on the solar cell it will make noise. I have seen and heard it happen.

Posted by Joe Morris (Member # 1553) on 03-02-2003, 09:40 PM:

I must correct my previous statement...they are Ultra Stereo Jaxlights...those are the red exciters. Had 'em put in before my theatre got bought out. we used to have the white ones in my lovely Monee's....and we never had a problem with sound....but excess light will cause buzzing and pops...the buzz is my favorite [Smile]

Posted by John Hawkinson (Member # 1135) on 03-02-2003, 10:03 PM:

Steve, a number of autofocus mechanisms emit IR, FYI.

Also, some platters using photocells might be affected, albiet briefly...

--jhawk

Posted by Steve Kraus (Member # 476) on 03-03-2003, 12:30 AM:

Autofocus? What's that? [Confused]

Posted by Bobby Henderson (Member # 840) on 03-03-2003, 01:11 AM:

If you have a tripod and some decent ambient light available, you'll get better quality booth photos by not using a flash. Flash photography has a bad tendency of flattening out shadow detail.

The best thing is to get a couple portable lights and rig them up to light your hardware and get a photo with good exposure. You don't necessarily have to spend a lot of money on real studio lights. It is possible to rig up a good set of lights just from materials you find at the hardware store. But even with good lights, you'll probably still need the tripod if you want to set a good, sharp F-stop.

Posted by Randy Stankey (Member # 64) on 03-03-2003, 09:24 AM:

Open the sound head door on a projector that still has a solar cell. Stand about two or three feet back. Hold a Bic lighter at waist level and flick it two or three times in quick succession. The flashes of light will cause a "Thump! Thump!" sound in the auditorium if the projector is running and the sound system is activated.

This was one of the demonstrations I used to give to kids who worked in the booth as to why they had to keep the overhead lights off when the movie was runnning.

I can just imagine what a camera flash would do to the sound in the auditorium! It must sound like a gunshot!

That having been said, I can imagine no reason why you can't take flash pictures in a projection booth as long as you keep the sound head doors closed and the sound system turned off. (Or at least in Non-Symc mode.)

Posted by Jack Ondracek (Member # 1466) on 03-03-2003, 09:48 AM:

quote:
from Justin...
Joe must be right, because when I was recently touring a booth with some other UDITOA members, the repeated flash photos were causing pops in the sound and Jim Goble gave us the "heads up" as to why.

That booth also uses the Jaxlights they've been talking about here.

Someone correct the practical theory here, if I don't get it quite right... You're using all the stuff from your old "forward scan" system... except you're installing an LED that doesn't provide anywhere near the gain you had with the
old exciter lamp. The surface-mounted solar cell is still there, with no physical shielding (as compared to a reverse scan system)... and you're kicking up the gain an obscene amount, thereby making the whole thing much more sensitive to hum inducing issues.... and camera flashes!

Oh... put a fluorescent trouble light around the front of one of these soundheads & see what happens! [Big Grin]

Posted by Jim Spohn (Member # 1547) on 03-03-2003, 10:28 AM:

Just take the pictures!!

Posted by Barry Floyd (Member # 385) on 03-03-2003, 10:31 AM:

I took that same booth tour that both Justin & Jack took several weeks ago down in Florida. Everytime the flash went off, there was a definite "pop" in the sound. I didn't realize what it was until Jim pointed it out to me.

Speaking of those photos.... Jack, did any of those photos Cheryl took of that infamous "booth wiring" turn out?? That was a classic hand written sign above the sound rack!!

Posted by Jack Ondracek (Member # 1466) on 03-03-2003, 10:32 AM:

I'll ask her about that, Barry... I know the sign you're talking about. Will email.

Posted by Greg Mueller (Member # 17) on 03-03-2003, 10:37 AM:

Try taking the pics without the flash. Then find someone with Photoshop. Bring the pics in and adjust the "Levels" You can pull more out of that pic than you think. Also experiment with "Unsharp Masking". Don't over do either or the pic will get noisey and weird looking. Let me know if I can help

Posted by Gordon McLeod (Member # 33) on 03-03-2003, 04:34 PM:

Some of the optical cue dectors and failsafes may have a issue with a bright flash

Posted by David Stambaugh (Member # 1102) on 03-03-2003, 04:52 PM:

Sounds like "no flash" is the safe way to go.

Posted by Bobby Henderson (Member # 840) on 03-03-2003, 06:02 PM:

Photoshop is only going to help so much on a dark, underexposed photo. Underexposed digital camera photos are especially problematic. They just tend to be very grainy by default. Using Photoshop to ramp up the levels may only amplify the pixel noise. Sometimes if I have to resort to such work, I'll try shifting the image over into L*a*b color space and tweaking the lightness channel's curve. Adjustment layers and layer blending techniques can also help.

You might have better luck with a carefully shot film camera photo (particularly if you use a tripod and time exposure). That can do wonders for controlling your grain and getting a better black value in the photo. Otherwise a lot of it just goes grey.

Posted by Tim Reed (Member # 137) on 03-03-2003, 07:17 PM:

quote:
You're using all the stuff from your old "forward scan" system... except you're installing an LED that doesn't provide anywhere near the gain you had

No, you're right; that's precisely the problem with those, Jack, and why they're not a good idea. You're bringing a nearly non-existant signal (and noise floor) up to death levels... just like Michael J. Fox did in the first scene of "Back to the Future".
[Big Grin]

Posted by William Hooper (Member # 71) on 03-04-2003, 12:44 AM:

I think I've used a flash on 35mm only a few times in the last several years. I've got a little 4" tall tabletop tripod on the camera, I just put it on program, set it down on a windowsill or armrest or whatever, hit the timer, & hold my hand behind the eyepiece.

The Polaroid pictures still use the flash. I'd like one of the new Kodak digital cameras, but the Polaroid makes me so popular when I use it. Folks love a picture they can hold in their hand. ("Take a picture of us so I can take it home!")

Posted by Daryl C. W. O'Shea (Member # 1303) on 03-04-2003, 12:49 AM:

Long exposures in a fairly dark booth look the best. A 4 second or longer exposure usually results in a cool picture with nicely defined LED lights, etc.

The top deck of a platter can be handy if you don't have a tripod. Just engage the motor so it doesn't move. The top of consoles also work well.

Posted by David Graham Rose (Member # 1450) on 03-05-2003, 02:04 PM:

I once opened a new theatre and had many people come around to take pictures of the inside of the projection rooms. Once, somone took a flash photograph of my main screens projector and it set off the end sequence shutdown. Evidently the light from the flash was enough to trigger a pulse from one of the opto sensors. Ever since then, I've always isolated the end sequence unit if anyone is going to take a photograph.

Posted by Ray Bernardi (Member # 1615) on 03-05-2003, 02:20 PM:

I tried the lighter deal, I've tried the flash again, and I've tried shining a flashlight directly at the photo cell. I can't make that thing pop or hiss at all. The only way I can get it to pop is to cut off the light to it. Wave the corner of an index card in front of it for example. It leads me to believe the sound is actually made when the light hitting the sensor is blocked out. Looking at the sound track makes me believe that even more. (Understand I'm just learning, if I'm wrong don't yell at me!)

EDIT: It's wrong. It reads the light.

Again, using an old sound head with white light.

I still think the flash is safe, in my case even with the sound doors open. I assume there are other systems where the stray light could be a problem. Perhaps when I can afford something more expensive I'll actually run into one of these! I can only hope!

[ 03-05-2003, 03:58 PM: Message edited by: Ray Bernardi ]

Posted by John Pytlak (Member # 331) on 03-11-2003, 10:19 AM:

I've had great results using the very fast Kodak MAX Versatility Plus (EI 800) film for available light photography. Unless you're going to make really large enlargements, the graininess is very reasonable for such a high speed film:

http://www.kodak.com/global/en/consumer/products/techInfo/e2452/e2452.shtml

http://www.kodak.com/cgi-bin/webCatalog.pl?product=KODAK+35+mm+Films

A strobe will usually cause a "pop" in the analog sound if the light falls on the photocell. Likewise, flourescent lights and even tungsten lights (especially those on an SCR dimmer) will cause a hum or buzz in the sound if they are picked up by the photocell.

[ 03-11-2003, 01:28 PM: Message edited by: John Pytlak ]

Posted by David Stambaugh (Member # 1102) on 03-11-2003, 11:37 AM:

I should have explained that these shots (if they happen) will be taken with a consumer-grade digital camera. There won't be any time to set up a tripod or do anything else elaborate. It will be point-and-shoot. [Frown]

Posted by John Pytlak (Member # 331) on 03-11-2003, 01:30 PM:

Some digital cameras have pretty good capability for available light exposures with long exposure times. If you can't use a tripod, just hold the camera steady on a firm surface.

Posted by Scott Norwood (Member # 30) on 03-11-2003, 01:36 PM:

How fast is the lens on that camera and what is its rough equivalent to film speed (ASA)?

I've never had a problem with using a flash camera in the booth as long as the soundhead doors are left closed.

Posted by David Stambaugh (Member # 1102) on 03-11-2003, 01:42 PM:

Heh. I don't own the camera yet ( [Wink]

to JP). Lens not likely going to be any faster f2.0, more likely f2.8 or thereabouts. Most of the cameras I've been looking at claim ISO 100, 200, and 400, although in flash mode they may be locked (100?). Sorry I don't have more details for you. I'm sure I could just point and shoot and get reasonably good snapshots (especially after doctoring them with Photoshop). I was really more concerned about the bright flash going off in an operating booth environment.

Posted by Daryl C. W. O'Shea (Member # 1303) on 03-11-2003, 01:50 PM:

The Kodak DX series cameras (that John and I both have) are lockable to 100, 200 or 400 ISO speeds even with the flash on. The F-stop is fixed at 2.8.

Other manually settable options are: exposure compensation, white balance (based on light source), colour mode, exposure metering, sharpness and shutter speed (fastest speed 1/2000 second).