OT: dimmer for Arri 650s

rmack350 wrote on 7/24/2008, 2:45 PM

You'd have to confirm that the lamp works. I know that I have some lower wattage bulbs for my 650s but what I had in mind was the 420W lamp for Omnis.

The standard lamp for the arri 650 is an FRK. Here's a link to some alternatives, but you'd need to confirm that the lamp works. It looks like you can lamp down to 500W using an FRG

http://www.ushio.com/products/entertainment/h-jcs.htm
http://www.arri.com/infodown/light/broch/en/ARRI_Junior_BRO_E.pdf

Arri lists the lamps in their brochure as CP81 (300W), CP82(500W), and CP89(650W).

<Time passes...> Okay, I've been assuming you had the 650 fresnel so those are the lamps I was looking for.

When you're mixing daylight with tungsten lamps you either have to gel the windows to match the tungsten or you gel the tungsten to match daylight. Lee CTBlue 201 is my choice but there are equivalents that work just fine. Stick with one brand since they don't match each other.

It's simpler to gel the lamps blue than to gel a whole window orange but here is where Bob's preference to work with daylight balanced units would really pay off. You need more light to supplement daylight and gelling tungsten gives you even less light so it's a lose/lose situation. It's easier to start with daylight lamps and the most you'll need color-wise is a light 1/8th or 1/4 magenta or green to dial it in. Sometimes in offices you have green tinted window glass or semi-daylight overheads so you might still need a little correction.

On Jbeale's site, here's the color correcting gel (but not the greens and magentas):
http://www.filmandvideolighting.com/cococogelsh.html

<more time passes...> Okay, I quit after this. Here's the Lee and Rosco links on the same site:
http://www.filmandvideolighting.com/leecolcorshe.html
http://www.filmandvideolighting.com/rococogelsh.html

Rob

rmack350 wrote on 7/24/2008, 3:00 PM

Hmmm. I've had it in my head for 20 years now that the Arri Open face and the Teenie were 600W, so I assumed we were talking about the Fresnel.

The Ushio catalog was fairly manageable compared to GE, Osram, and Sylvania. You should be able to figure out from there what the lower wattage lamps are. Mole prints a list right on the instrument. Arri should too but might not...in fact, you might be able to find the list of equivalents on the Mole site.

Autotransformers are no fun to carry around but they'll dim just about anything, including motors. On jbeale's link to the household dimmer, Push On/Off is a good feature because you can keep the dimmer setting more easily.

Rob

john-beale wrote on 7/24/2008, 6:55 PM

I just assumed it was the Arri 650W open face, http://www.filmandvideolighting.com/arar65opfali.html

but you're right, there's also the Arri 650W fresnel and just to be confusing there's also an Arri 600W open face. I have no idea why they'd have two open face lights at such similar power levels.

rmack350 wrote on 7/24/2008, 10:05 PM

I think the 600 is a more compact open faced unit. I never see them in the field, but I haven't worked as an freelance electric since 2001, so I don't see as much as I used to.

A lot of Arri kits were sold throughout the 90s and these always had some combination of the 650 and 1KW open face lights, the 300 Fresnel, or the 650 fresnel. I worked with a Swiss guy once in that decade who swore by the Arris because they held up to salt air. He'd worked on Lord of the Flies and said that all the Mole fixtures rusted up immediately and were pretty much useless except to block up cars on.

Rob

DrLumen wrote on 7/24/2008, 10:42 PM

Just to expand on what was said about using theatrical/stage dimmers, the cheap ones don't have the noise filtering like the higher quality dimmers. Typically the cheapo American DJ, Behringer or similar cause noise also. They don't cause as much noise as home dimmers but still can be noisy. While part of the noise is caused by the lamp filament vibrating, noise can also be induced on the power lines (hence the ground switch on some instrument amps).

The higher quality theatrical dimmer packs have toroidal filtering to prevent filament singing and power line noise. Personally, I stay away from the cheapo dimmer packs like the plague.

YMMV.

musicvid10 wrote on 7/25/2008, 6:49 AM

**Typically the cheapo American DJ, Behringer or similar cause noise also.**
Well, with great certainty I can say they are much quieter than the low-tech autotransformer and Triac (home dimmer) solutions suggested above, and with greater load carrying and safety. Household dimmers buzz all the time and can fry if you plug them in with a load connected, and autotransformers have the problem of inductive line noise which gets worse as the load increases, while the stage dimmers do not.

I've used four DP-DMX20L on local gigs for years now, and never experienced noise through the sound system even when they were plugged into the same circuit as the sound equipment. By far the biggest line noise problems in the rooms we play come from standard flourescent lighting and home-type dimmers. However, just to satisfy my own curiosity, I'll run some quantitative line noise tests on them under load and post the results back on this thread sometime in August.

Perhaps you are thinking of the really low-end dimmers like Chauvet. I tried one once and that was it. Never again. Really though, those Elations get used 4-6 times a month, even on outdoor generators and never a problem. That's why I suggested he try one.

Dan Sherman wrote on 7/25/2008, 11:10 AM

A one word solution to your problem is "DEDO".
Fresnel, dimmer, barn doors.
Compact, light weight units.
Replacement lamps are about 8 dollars each and last 400 hrs plus.
What a joy to work with.
And, NO, I don't sell them.

rmack350 wrote on 7/25/2008, 12:11 PM

But if you did sell them you'd probably get a big margin because they're very expensive. Nice lights but quite an investment. I'd like to have one plus a focal spot for it.

The cheap solution is to back the light up and throw a few scrims in it. If you are out of space, out of scrims, and don't want to relamp (it's a hassle if you have to keep switching lamps back and forth) then you could use a sheet of ND gel or lay on the diffusion. Since dimmers change color temp they can cause a little discontinuity between shots.

I find the little household dimmers (aka squeezers) do just fine when setting up practicals in the background. You can't scrim those.

Rob

john-beale wrote on 7/25/2008, 4:51 PM

"autotransformers have the problem of inductive line noise which gets worse as the load increases."

This is drifting off topic but... I don't understand the statement above. Can you explain how powering a resistive load (lamp) through an autotransformer generates noise? I know the autotransformer has inductance, but I don't know how to make it generate noise, without also having a switching element somewhere. (If you switch the load on and off, of course you can generate noise.)

If you could link to some online explanation of the effect you're talking about, that would be helpful.