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another 1k hanging fresnel question

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Craig Alan
another 1k hanging fresnel question
on Aug 2, 2013 at 10:41:55 pm

We have some diffusion paper and barn doors on the fresnels. Is there any rule of thumb about using these in flood vs spot position and does it effect the lamp burning out?

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Bill Davis
Re: another 1k hanging fresnel question
on Aug 4, 2013 at 5:00:47 am

I'm presuming you mis-typed and that the diffusion you're using is either proper heat resistent Gel or even better something like tough spun.

If you're actually using any type of paper - and putting it any closer than 3 feet in front of the instrument lens - don't let the fire marshall see the rig.

You laugh, but I knew a guy who's dad was an architect who once told me he was going to use plain vellum on his ancient Smith Victor open face 650s. I gently suggested he run out and buy a quality fire extinguisher in advance.

A quality constructed fresnel should dissiate the heat properly if you're using a lamp within the fixtures recommended range. So spot verses flood should have no reall effect on lamp life.

What will, are the traditional mis-steps in hot light handling. Touching bare bulbs with bare fingers when cold and getting skin oils on them will shorten lamp life. Jarring the lamp housing when the unit is active or during cool down can make filiments more fragile. And blocking venting so the instrument runs hotter than it's specs are all good ways to shorten lamp life.

Hope that helps.

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Craig Alan
Re: another 1k hanging fresnel question
on Aug 4, 2013 at 1:03:30 pm

Yes its a proper diffusion gel. I think its rosco and tough spun.

The reason I asked about spot vs flood is that the bulbs that went south had a bubble on the side facing the silver reflector on the inside of the lamp.

As far as movement - well they are a pole controlled fixtures and yes we make adjustment with the lights on.

We are talking over 6 months of heavy use.

In any case just wondering if shape makes any difference and why some of these bulbs are so much more expensive than others.

The ones we have are the cheapest of the options but the name brand (Sylvania / Osram).

Are Impact brand bulbs as good?

What does the different shapes change?

What does EGR vs EGT mean?

Sylvania / Osram
EGR (750W/120V) Lamp
Price: $34.95

Sylvania / Osram
EGT (1000W/120V) Lamp
$13.99

Why the different price points?

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Bill Davis
Re: another 1k hanging fresnel question
on Aug 5, 2013 at 12:00:45 am

[Craig Alan] "In any case just wondering if shape makes any difference and why some of these bulbs are so much more expensive than others.
"


The shape is dictated by the socket and orientation.

The letter codes are how manufacturers catalog the lamps. The EGR is the 750 watt version, the EGT is the 1000W. The price difference is probably just related to economies of scale. The 1000w is probably manufactured in much higher quantities and used in many more instruments.

Sometimes lamps just fail. It's part of the extreme high heat environment they operate in.

I presume someone's already told you what we mention here all the time about NEVER touching the lamp surface with bare fingers when changing them. Skin oil can cause surface heating and cooling expansion differences that can lead to premature lamp failure.

Other than that, just make sure the instruments hot air venting is clear - and use them as designed. Which is to say, turn them on and let them operate at the temperature they expect. Then turn them off and let them cool down before you move or shock them. That doesn't guarantee a particular lamp won't fail before it's due - just helps. It also doesn't mean you cant operate them differently - turning them on or off rapidly for special effects or changing your mind once you flip a switch - these are consumables and they're meant to be consumed.

It's just smart to be aware of how they work.

Good luck.

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Craig Alan
Re: another 1k hanging fresnel question
on Aug 5, 2013 at 4:15:01 pm

Did some searching. The letters are an ANSI Code. But it is not clear exactly how these are defined. I believe there is a listing (and it is written by a specific organization) but it is not obvious or a simple top google hit away. On one description of a bulb of a certain code and shape it implied the shape helped determine the throw. I don't have the link cause I thought I'd get more comprehensive hits.

And yes I know not to touch these types of bulbs.

Arri has some 1K lights that they say you should or could use 750 bulbs and get the same output. This suggests that there are other variables that determine how bright the lamp gets.

Arri and Desisti both use these G22 bulbs and I need to order a bunch so I was hoping for some specific recommendation. If not I'll stay with what I got last time.

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Craig Alan
called Arri and DeSisti
on Aug 5, 2013 at 4:58:42 pm

They both said EGT is the correct bulb type for those 1k fresnels. Not sure why BH would have anything else listed as options. Further they don't list the recommended one that they also sell and is the cheapest.

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