Photoflood datasheet?

[jpentecost]

Hello,

Sorry that my first post here is a question. I have an idea for lighting using No1 and No2 photofloods, I was looking into a classic "Series Parallel" switch (but remotely controlled with a relay) and then I realised that I can get a really rather good DMX controllable dimmer pack with four channels for about £80, which is far better for my purpose.

Google has not been kind to my search for a photoflood data sheet. What I would love to find out is how long a 230/240v photoflood will last when driven at 50% of it's capacity (so say 120V or a chopped PWM of 50%). I tried GE and Phillips but with no luck .. Does anyone else have any information they could let me have.

Justin

 

[ic-racer]

Hello,

Sorry that my first post here is a question. I have an idea for lighting using No1 and No2 photofloods, I was looking into a classic "Series Parallel" switch (but remotely controlled with a relay) and then I realised that I can get a really rather good DMX controllable dimmer pack with four channels for about £80, which is far better for my purpose.

Google has not been kind to my search for a photoflood data sheet. What I would love to find out is how long a 230/240v photoflood will last when driven at 50% of it's capacity (so say 120V or a chopped PWM of 50%). I tried GE and Phillips but with no luck .. Does anyone else have any information they could let me have.

Justin

Some info I have on enlarging lamp voltage:

 

[Jim Jones]

Until LEDs became economical, I used 40 and 60 Watt household incandescent lamps in series as a fairly bright night light. The 60 Watt lamp glowed a dull red. The 40 Watt lamp's output was greatly reduced, but sufficient for the purpose. It lasted up to 3 years at 24 hours a day before failure. The 60 Watt lamp never burned out. I neglected to meter the light output or measure the voltages across each lamp.

Many years ago we were plagued by short lamp life in 16mm movie projectors. Wiring a 6.3 volt transformer as a 6.3 volt step-down transformer at least doubled lamp life.

 

[mjork]

There is a nice collection of data sheets available here: http://www.donsbulbs.com/cgi-bin/r/t.pl/library.html
Don't know if that helps in your particular case, though.

 

[AgX]

Why would someone use Photoflood lamps today?

Well, I bought some... but only for use in decorative luminaires as substitutes for household bulbs during photographing.

 

[jpentecost]

AgX , because the look is like no other fixture. The softness from a china ball is quite special. There are things called "JEM Balls" with 1KW halogen fittings but the light is different. Photofloods have a softness I can't find elsewhere. Usually on a film set you just turn them on and change the bulb every half day. This fixture is for shooting stop motion hence the need for information ..

 

[M Carter]

With tungsten bulbs like photofloods, I don't think data charts will be very accurate anyway. Ever notice that 90% of the time a bulb burns out, it's when you switch it on?

If you keep tungsten fixtures on dimmers and bring them up with the knob vs. switching on, they'll last far longer than spec'd. As long as you don't move them when they're running (you can move them carefully but a good enough bump when powered can break the filament). And running them at half power could extend their life far longer. I dunno if you'll find data that specific. Just stock up on spares!

I prefer paper chinas to nylon myself. Have a look at filmtools.com, they sell a pretty cool china holder where the globe and the ball are held in place - vs. a swaying, hot globe on a wire bumping the paper. They take proprietary balls, but if you don't mind a few extra bucks and an initial investment, they're pretty cool.

They also sell an inexpensive fixture and 500 and 1k globes for regular chinas… might be easier to replace than photofloods. Myself, I wired some bayonet holders that take 250w modeling lights when I don't need 1k of light.

If your concern is constant exposure from frame to frame (for stop motion) - you'd want to do some tests. DMX may dim in a way that's noticeable from frame to frame, esp. if you're using a shutter speed faster than mains power (1/60th US, 50th UK). If this is digital, you may find one of the time lapse flicker plugins will even things out.

 

[jpentecost]

I prefer paper chinas to nylon myself. Have a look at filmtools.com, they sell a pretty cool china holder where the globe and the ball are held in place - vs. a swaying, hot globe on a wire bumping the paper. They take proprietary balls, but if you don't mind a few extra bucks and an initial investment, they're pretty cool.

The investment is not 100% required .. Have a look at Chris Plevin's post int he bottom of this page ..

http://www.cinematography.net/edited-pages/CHINESE.HTM

Not sure what the "Plastic tube" refered to in the first post is .. I suspect they are wrong and it's brass tube with a little rubber or plastic sheath around it.

 

[jpentecost]

If your concern is constant exposure from frame to frame (for stop motion) - you'd want to do some tests. DMX may dim in a way that's noticeable from frame to frame, esp. if you're using a shutter speed faster than mains power (1/60th US, 50th UK). If this is digital, you may find one of the time lapse flicker plugins will even things out.

There's a book in that (Not a very interesting one and not one with a wide audience, a book all the same ..) Interesting aside ... Film has many fewer flicker artifacts than digital for some reason .. This job http://www.portablemotioncontrol.com/rabbit.html was shot both with a Mitchell and a Canon 50D. The video you see on Vimeo is from the 50D (the film disappeared into the production so I never got a copy) and about half way through there is a "chink" in the light, pretty sure it was not the camera so it must have been a variation in the voltage. However when we telecined the film I warned the operator that it would need a second pass for the exposure change, however when it ran there was nothing .. it held all the way through with no change at all ..

 

[M Carter]

When my kids were little - well, 12, 14... I'd set up a softbox and a little digital camera and go to bed. They'd sit up til 4AM making claymation movies or stuffed-snimal stop motion, gathering up rpops from all over the studio - I showed them how to dump the folder of pics into iMovie. They'd do voiceover and in the morning I'd see some really whacked out stuff...

My son just graduated from UT Austin's film school… check out his website. He kind of stuck with the concept!

I've never done that kind of work, but when I've played with time lapse on my DSLR, I at least learned to do the unlocked-lens thing to maintain a constant aperture! I was amazed how much flicker you got just from inaccurate aperture closing.

Still, "Nightmare Before Xmas" is one of my favorite films. Amazing job of world-building, they knocked that one outta the park.

 

[jpentecost]

I've never done that kind of work, but when I've played with time lapse on my DSLR, I at least learned to do the unlocked-lens thing to maintain a constant aperture! I was amazed how much flicker you got just from inaccurate aperture closing.

There are many people who find the concept very difficult to understand, of course for stills it's not important as a 1% variation in exposure between frames is not even slightly significant. There are lots of solutions, and the only one I refuse to use is the "Unlocked lens" or "tape over the contacts" thing ..

On "Corpse Bride" they were originally going to shoot on film but changed to digital stills at the last moment and in the first set of camera tests (Using Nikon cameras and lenses) they had flicker in the background. The problem was solved by a chap called Andy Bowman who removed the stopdown pin from an AIS lens and this stopped the flicker. (Then they moved into another circle of hell entitled "Power supply issue flicker"). My favoured solution is Nikon AIS lenses on a Canon body and the aperture sets itself and stays there (of course my actual favoured solution is a Mitchell with a Jackson Woodburn motor and a Nikon mount, but I've not shot with film for about six months.)

Or this .. a lovely lens I got off a Fuji STX camera I bought at a charity sale for £5 with a £1 M42 to Canon adapter ..

 

[M Carter]

That's a good solution, my first DSLR video work was with Nikkor primes on a T2i. Sold the 2Ti when Nikon got their video look together though.