Photometric Data

[esambell]

Does anyone out there know where the photometric information is stored for a fixture? I see beam and field angles in the Object Info pane, but nothing indicate intensity. I'm trying to use the Photometer or Photogrid tools to estimate the intensity of some audience lighting, but I'm getting some values that don't make sense. I would like to verify what information VW uses to calculate the number of Foot-Candles. I'm using version 12.5.1 on a PC.

Thanks,

Eric

[Ericoxer]

when you click on the data tab, there is a box called "light Info Record", in there you should find everything you need.

[esambell]

Tragically that record does not seem to be attached to the fixture. I used the instrument insertion tool, so I don't think that is the problem. I'm at a loss here. The information must be coming from somewhere?

Thanks,

Eric

[michaelk]

Very interesting. If you look in the data tab of the OIP, the only data in any of the fields is

Device Type: Light

Beam Angle: 0.0?

Field Angle: 0.0?

All others are blank. Even though the correct wattage, frame size, beam angle, and field angle appear in the Shape Tab.

I think Eric is looking for the "Candlepower" (same as peak candela?) of an instrument. If I remember, the formula is footcandles = Candlepower/distance squared. So you could figure it out the old fashioned way.

But I seem to remember that on symbols I created myself all the correct information stays in the Data Tab. Am I just dreaming that?

I just tried to compare the photometric performance of an instrument in Spotlight against the information in in my very dog-eared copy of Mumm's Photometric Handbook. (Found an old Field Template in the book!)

I compared a S4 36?. The field angles agreed to within 5/8" (for a 10" throw distance), but the footcandles at a given distance are way off. For any given distance they show a value only 81% what Mumm says it should be.

But the Altman 360Q was dead on. So was the Altman Shakespeare.

Could be the vagueries of which flavor of HPL 575 was used for the calculations.

Hope that helps.

But I also wonder where the data went.

Michael

[klinzey]

The data is stored in the light info record attached to the symbol definition. If you change it, it will update the info for all the fixtures. The data is from the manufacture specifications at the time the symbol was created, and if you have been following ESTA standards committee, you will know that how the manufactures measure the light output varies a lot.

[michaelk]

Kevin

This is something I've never understood.

Where is actual record for a particular instrument?

I can find the record format, but not the actual data that Eric was looking for.

Thanks

Michael

[klinzey]

Edit the symbol from the resource browser. When you are in symbol edit mode, de-select everything then change the record info in the data tab. Then just exit the symbol.

[michaelk]

Thanks Kevin

I've always wondered about that.

Just curious: Why doesn't that data show up outside the edit mode? Like in the Object Info Pallet?

Michael

[klinzey]

The record data deosn't show because the symbol is inside of the plug-in object. The data that is shown when the lighting device is selected would be data that is atatched to the lighting device.

[esambell]

Ahhh...Thanks everyone. It all makes sense now!

Eric

[Jim_Allen]

Ok. Cannot find a way to edit the symbol in the Resouce Browser - Missing something.