making my own ies file

radiance-general
1

Hello again,

Im making my own ies file for a spotlight i am using in a lab from data i found at the manufacturers website. i have a graph of angle against brightness and i know the format of such a file from readin RwR. however i can seem to find a description for some of the values needed, either in the book or in the online manuels

the file i have made so far looks as so, but the text in square brackets are the values im not sure of (ignore the oridnary parenthesis, i simply havent measured my spotlight yet.). i havent got access to the iesna standard and so was wondering if anyone on the list has knowledge of this area.

TILT=NONE

1 [lumens per lamp] [candela multiplier] 11 [photometric type] [units type] (w) (l) (h)
[ballast factor] 1 4000
0 0.5 1.5 3 4 5 6 7.5 9 11 17
0
1880000 1800000 1600000 1000000 600000 400000 250000 120000 100000 60000 0

i think that all the square bracket values have to be 1, but the one im most unsure of is the lumens per lamp value. this is most definately not 1, does anyone know what this is and how i calculate this for my spotlight??

thanks in advance, any help much appreciated as usual (wish i could give something back!).

Chris

p.s. still havent solved my last email either if anyone has any suggestions...

···

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2

Chris.

You can find the description of the IES file standard in the appendix of
this
document:

PS: Did the manufacturer not offer IES files directly?
      Seems strange if they had the raw data.

Thomas

···

_____

From: [email protected]
[mailto:[email protected]] On Behalf Of Chris
Foster
Sent: 03 August 2006 09:33
To: Radiance general discussion
Subject: [Radiance-general] making my own ies file

Hello again,

Im making my own ies file for a spotlight i am using in a lab from data
i found at the manufacturers website. i have a graph of angle against
brightness and i know the format of such a file from readin RwR. however
i can seem to find a description for some of the values needed, either
in the book or in the online manuels

the file i have made so far looks as so, but the text in square brackets
are the values im not sure of (ignore the oridnary parenthesis, i simply
havent measured my spotlight yet.). i havent got access to the iesna
standard and so was wondering if anyone on the list has knowledge of
this area.

TILT=NONE

1 [lumens per lamp] [candela multiplier] 11 [photometric type] [units
type] (w) (l) (h)
[ballast factor] 1 4000
0 0.5 1.5 3 4 5 6 7.5 9 11 17
0
1880000 1800000 1600000 1000000 600000 400000 250000 120000 100000 60000
0

i think that all the square bracket values have to be 1, but the one im
most unsure of is the lumens per lamp value. this is most definately not
1, does anyone know what this is and how i calculate this for my
spotlight??

thanks in advance, any help much appreciated as usual (wish i could give
something back!).

Chris

p.s. still havent solved my last email either if anyone has any
suggestions...

-------------------------------------------------------------------
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If you are not a named addressee, you must not use, retain or
disclose such information.

NPL Management Ltd cannot guarantee that the e-mail or any
attachments are free from viruses.

NPL Management Ltd. Registered in England and Wales. No: 2937881
Registered Office: Serco House, 16 Bartley Wood Business Park,
Hook, Hampshire, United Kingdom RG27 9UY
-------------------------------------------------------------------

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***********************************************************************************

3

Hi Thomas

Thanks for getting back to me, ill look on the website.

i havent actually contacted the manufacturer directly (its arri out of interest; http://www.arri.com/entry/lighting.htm), would be wise to but i thought i would learn more by making my own. They didnt have an ies file on the website that i could find, just this photometric data page.
after looking at your suggested website (which is very good thankyou) the description of lumens per lamp isnt given by arri so i'll have to request an ies file afterall

Thanks again

Chris

···

-----Original Message-----
From: [email protected] [mailto:[email protected]]On Behalf Of Bleicher, Thomas
Sent: 03 August 2006 09:40
To: Radiance general discussion
Subject: RE: [Radiance-general] making my own ies file

Chris.

You can find the description of the IES file standard in the appendix of this
document:

PS: Did the manufacturer not offer IES files directly?
      Seems strange if they had the raw data.

Thomas

  _____

From: [email protected] [mailto:[email protected]] On Behalf Of Chris Foster
Sent: 03 August 2006 09:33
To: Radiance general discussion
Subject: [Radiance-general] making my own ies file

Hello again,

Im making my own ies file for a spotlight i am using in a lab from data i found at the manufacturers website. i have a graph of angle against brightness and i know the format of such a file from readin RwR. however i can seem to find a description for some of the values needed, either in the book or in the online manuels

the file i have made so far looks as so, but the text in square brackets are the values im not sure of (ignore the oridnary parenthesis, i simply havent measured my spotlight yet.). i havent got access to the iesna standard and so was wondering if anyone on the list has knowledge of this area.

TILT=NONE

1 [lumens per lamp] [candela multiplier] 11 [photometric type] [units type] (w) (l) (h)
[ballast factor] 1 4000
0 0.5 1.5 3 4 5 6 7.5 9 11 17
0
1880000 1800000 1600000 1000000 600000 400000 250000 120000 100000 60000 0

i think that all the square bracket values have to be 1, but the one im most unsure of is the lumens per lamp value. this is most definately not 1, does anyone know what this is and how i calculate this for my spotlight??

thanks in advance, any help much appreciated as usual (wish i could give something back!).

Chris

p.s. still havent solved my last email either if anyone has any suggestions...

-------------------------------------------------------------------
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privileged material; it is for the intended addressee(s) only.
If you are not a named addressee, you must not use, retain or
disclose such information.

NPL Management Ltd cannot guarantee that the e-mail or any
attachments are free from viruses.

NPL Management Ltd. Registered in England and Wales. No: 2937881
Registered Office: Serco House, 16 Bartley Wood Business Park,
Hook, Hampshire, United Kingdom RG27 9UY
-------------------------------------------------------------------

***********************************************************************************
This e-mail, (and any attachments) is confidential and may be privileged. It may be read, copied and used by the intended addressee only. If you have received this in error please contact BDP immediately.

If you have any queries, please contact the sender.
***********************************************************************************
Building Design Partnership
Registered in England No 2207415:
Registered Office: Building Design Partnership Ltd, Sunlight House, PO Box 85, Quay Street, Manchester, M60 3JA, http://www.bdp.co.uk
***********************************************************************************

-------------------------------------------------------------------
This e-mail and any attachments may contain confidential and/or
privileged material; it is for the intended addressee(s) only.
If you are not a named addressee, you must not use, retain or
disclose such information.

NPL Management Ltd cannot guarantee that the e-mail or any
attachments are free from viruses.

NPL Management Ltd. Registered in England and Wales. No: 2937881
Registered Office: Serco House, 16 Bartley Wood Business Park,
                   Hook, Hampshire, United Kingdom RG27 9UY
-------------------------------------------------------------------

4

Hi Chris,

Arri doesn't provide IES or EULUMDAT data for their luminaires, but they have a photometric calculator on their website.
I measured four different types of luminaires for my thesis and created IES files, tell me which one you want, maybe i can help you.
Regards,

Christian

···

--

Christian Fusenig
Dipl.-Ing. Medientechnik
Beim Schlump 27/07
20144 Hamburg
mobil: 0179/5975845

5

Hello Christian,

Thanks for getting back to me, much appreciated.

The photometric calculator (PC) Arri has looks nice but isnt really much help when trying to make an ies file. I have printed off a graph from the PC and have used a ruler to try and get some angle and brightness values for use in my ies file but it cant imagine that its very accurate.
The light i physical and want to model have is the ARRI Daylight Compact 4000W (not the theatre one) with a fresnal lens. HMI 4000 W/SE G38.
I want to model it in spot, midflood and flood focus range.

For my spot focus my draft ies looks as below

TILT=NONE

1 [lumens per lamp] 1 12 1 1 2 -.376 0 0
1 1 4000
0 0.5 1.5 3 4 5 6 7.5 9 11 17 90
0
1880000 1800000 1600000 1000000 600000 400000 250000 120000 100000 60000 0 0

i dont know what value i should use for the lumens per lamp, any suggestions? from what you know am i doing anything else wrong??

Thanks for your time

Chris

···

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of
Christian Fusenig
Sent: 03 August 2006 11:31
To: [email protected]
Subject: [Radiance-general] Re: making my own ies file

Hi Chris,

Arri doesn't provide IES or EULUMDAT data for their luminaires, but they
have a photometric calculator on their website.
I measured four different types of luminaires for my thesis and created
IES files, tell me which one you want, maybe i can help you.
Regards,

Christian

--

Christian Fusenig
Dipl.-Ing. Medientechnik
Beim Schlump 27/07
20144 Hamburg
mobil: 0179/5975845

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If you are not a named addressee, you must not use, retain or
disclose such information.

NPL Management Ltd cannot guarantee that the e-mail or any
attachments are free from viruses.

NPL Management Ltd. Registered in England and Wales. No: 2937881
Registered Office: Serco House, 16 Bartley Wood Business Park,
                   Hook, Hampshire, United Kingdom RG27 9UY
-------------------------------------------------------------------

6

If you know what kind of lamp you want to use, you can go to philips or ge's website and find the lamp there. They should have the mean and initial lumens listed that you can then put into your IES file. For the ballast factor, you can use 1, or you can go to a site like advancetransformer.com and find a ballast that will work with whatever lamp you've chosen and use that ballast factor (although generally you can find a ballast for your lamp that has whatever ballast factor you want, so you could probably just set this at whatever you want it to be).

Dave

Chris Foster wrote:

···

Hello again,
Im making my own ies file for a spotlight i am using in a lab from data i found at the manufacturers website. i have a graph of angle against brightness and i know the format of such a file from readin RwR. however i can seem to find a description for some of the values needed, either in the book or in the online manuels
the file i have made so far looks as so, but the text in square brackets are the values im not sure of (ignore the oridnary parenthesis, i simply havent measured my spotlight yet.). i havent got access to the iesna standard and so was wondering if anyone on the list has knowledge of this area.
TILT=NONE
1 [lumens per lamp] [candela multiplier] 11 [photometric type] [units type] (w) (l) (h)
[ballast factor] 1 4000
0 0.5 1.5 3 4 5 6 7.5 9 11 17
0
1880000 1800000 1600000 1000000 600000 400000 250000 120000 100000 60000 0
i think that all the square bracket values have to be 1, but the one im most unsure of is the lumens per lamp value. this is most definately not 1, does anyone know what this is and how i calculate this for my spotlight??
thanks in advance, any help much appreciated as usual (wish i could give something back!).
Chris
p.s. still havent solved my last email either if anyone has any suggestions...

-------------------------------------------------------------------
This e-mail and any attachments may contain confidential and/or
privileged material; it is for the intended addressee(s) only.
If you are not a named addressee, you must not use, retain or
disclose such information.

NPL Management Ltd cannot guarantee that the e-mail or any
attachments are free from viruses.

NPL Management Ltd. Registered in England and Wales. No: 2937881
Registered Office: Serco House, 16 Bartley Wood Business Park,
Hook, Hampshire, United Kingdom RG27 9UY
-------------------------------------------------------------------

------------------------------------------------------------------------

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7

Hi Dave

yeah i know what type of lamp, it was in the last email i wrote to christian, its a 4000w fresnal lens spotlight from Arri. how do the mean and initial lumens value help me? do i use one of them in the 'lumens per lamp' value for the ies file

thanks chris

···

-----Original Message-----
From: [email protected] on behalf of J. David Maino
Sent: Thu 8/3/2006 2:09 PM
To: Radiance general discussion
Subject: Re: [Radiance-general] making my own ies file

If you know what kind of lamp you want to use, you can go to philips or ge's website and find the
lamp there. They should have the mean and initial lumens listed that you can then put into your IES
file. For the ballast factor, you can use 1, or you can go to a site like advancetransformer.com and
find a ballast that will work with whatever lamp you've chosen and use that ballast factor (although
generally you can find a ballast for your lamp that has whatever ballast factor you want, so you
could probably just set this at whatever you want it to be).

Dave

Chris Foster wrote:

Hello again,

Im making my own ies file for a spotlight i am using in a lab from data
i found at the manufacturers website. i have a graph of angle against
brightness and i know the format of such a file from readin RwR. however
i can seem to find a description for some of the values needed, either
in the book or in the online manuels

the file i have made so far looks as so, but the text in square brackets
are the values im not sure of (ignore the oridnary parenthesis, i simply
havent measured my spotlight yet.). i havent got access to the iesna
standard and so was wondering if anyone on the list has knowledge of
this area.

TILT=NONE

1 [lumens per lamp] [candela multiplier] 11 [photometric type] [units
type] (w) (l) (h)
[ballast factor] 1 4000
0 0.5 1.5 3 4 5 6 7.5 9 11 17
0
1880000 1800000 1600000 1000000 600000 400000 250000 120000 100000 60000 0

i think that all the square bracket values have to be 1, but the one im
most unsure of is the lumens per lamp value. this is most definately not
1, does anyone know what this is and how i calculate this for my spotlight??

thanks in advance, any help much appreciated as usual (wish i could give
something back!).

Chris

p.s. still havent solved my last email either if anyone has any
suggestions...

-------------------------------------------------------------------
This e-mail and any attachments may contain confidential and/or
privileged material; it is for the intended addressee(s) only.
If you are not a named addressee, you must not use, retain or
disclose such information.

NPL Management Ltd cannot guarantee that the e-mail or any
attachments are free from viruses.

NPL Management Ltd. Registered in England and Wales. No: 2937881
Registered Office: Serco House, 16 Bartley Wood Business Park,
Hook, Hampshire, United Kingdom RG27 9UY
-------------------------------------------------------------------

------------------------------------------------------------------------

_______________________________________________
Radiance-general mailing list
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_______________________________________________
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-------------------------------------------------------------------
This e-mail and any attachments may contain confidential and/or
privileged material; it is for the intended addressee(s) only.
If you are not a named addressee, you must not use, retain or
disclose such information.

NPL Management Ltd cannot guarantee that the e-mail or any
attachments are free from viruses.

NPL Management Ltd. Registered in England and Wales. No: 2937881
Registered Office: Serco House, 16 Bartley Wood Business Park,
                   Hook, Hampshire, United Kingdom RG27 9UY
-------------------------------------------------------------------

8

Chris,

Say you had an initial lumen value of 15,000lm for the lamp you've chosen. All you would have to do would be replace [lumens per lamp] with 15000. The mean lumens will be a lower value than the intital lumens. If you are using a light loss factor in your calculations, you should use one of the following combinations:

a) use the initial lumens in your IES file and use an appropriate value for the lamp lumen depreciation in your light loss factor (the lamp lumen depreciation value will depend on the lamp chosen)

b) use the mean lumens in your IES file and use a value of 1 for the lamp lumen depreciation in your light loss factor, since the mean lumens already take the lamp lumen depreciation into account.

Hope that helps!
Dave

Chris Foster wrote:

···

Hi Dave

yeah i know what type of lamp, it was in the last email i wrote to christian, its a 4000w fresnal lens spotlight from Arri. how do the mean and initial lumens value help me? do i use one of them in the 'lumens per lamp' value for the ies file

thanks chris

-----Original Message-----
From: [email protected] on behalf of J. David Maino
Sent: Thu 8/3/2006 2:09 PM
To: Radiance general discussion
Subject: Re: [Radiance-general] making my own ies file

If you know what kind of lamp you want to use, you can go to philips or ge's website and find the
lamp there. They should have the mean and initial lumens listed that you can then put into your IES
file. For the ballast factor, you can use 1, or you can go to a site like advancetransformer.com and
find a ballast that will work with whatever lamp you've chosen and use that ballast factor (although
generally you can find a ballast for your lamp that has whatever ballast factor you want, so you
could probably just set this at whatever you want it to be).

Dave

Chris Foster wrote:
> Hello again,
> > Im making my own ies file for a spotlight i am using in a lab from data
> i found at the manufacturers website. i have a graph of angle against
> brightness and i know the format of such a file from readin RwR. however
> i can seem to find a description for some of the values needed, either
> in the book or in the online manuels
> > the file i have made so far looks as so, but the text in square brackets
> are the values im not sure of (ignore the oridnary parenthesis, i simply
> havent measured my spotlight yet.). i havent got access to the iesna
> standard and so was wondering if anyone on the list has knowledge of
> this area.
> > TILT=NONE
> > 1 [lumens per lamp] [candela multiplier] 11 [photometric type] [units
> type] (w) (l) (h)
> [ballast factor] 1 4000
> 0 0.5 1.5 3 4 5 6 7.5 9 11 17
> 0
> 1880000 1800000 1600000 1000000 600000 400000 250000 120000 100000 60000 0
> > i think that all the square bracket values have to be 1, but the one im
> most unsure of is the lumens per lamp value. this is most definately not
> 1, does anyone know what this is and how i calculate this for my spotlight??
> > thanks in advance, any help much appreciated as usual (wish i could give
> something back!).
> > Chris
> > p.s. still havent solved my last email either if anyone has any
> suggestions...
> > > >
>
> -------------------------------------------------------------------
> This e-mail and any attachments may contain confidential and/or
> privileged material; it is for the intended addressee(s) only.
> If you are not a named addressee, you must not use, retain or
> disclose such information.
>
> NPL Management Ltd cannot guarantee that the e-mail or any
> attachments are free from viruses.
>
> NPL Management Ltd. Registered in England and Wales. No: 2937881
> Registered Office: Serco House, 16 Bartley Wood Business Park,
> Hook, Hampshire, United Kingdom RG27 9UY
> -------------------------------------------------------------------
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Radiance-general mailing list
> [email protected]
> http://www.radiance-online.org/mailman/listinfo/radiance-general

_______________________________________________
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If you are not a named addressee, you must not use, retain or
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NPL Management Ltd cannot guarantee that the e-mail or any
attachments are free from viruses.

NPL Management Ltd. Registered in England and Wales. No: 2937881
Registered Office: Serco House, 16 Bartley Wood Business Park,
Hook, Hampshire, United Kingdom RG27 9UY
-------------------------------------------------------------------

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9

Chris.

You need to get the terminology right:

The "lamp" you're describing is a "luminaire": the lamp
is the small glass bulb that's inside it. (Yes, we do this
on purpose to confuse people :wink:

The lamp for your luminaire is indicated as

HMI 4000 W/SE G38

and is described here:

http://www.osram.com.ro/pdf/service_corner/technicalinfo/4000WSE_E.pdf

and gives you a modes 380000 lumens.

I suppose that's why the luminaires are called 'daylight'

Thomas

···

_____

From: [email protected]
[mailto:[email protected]] On Behalf Of Chris
Foster
Sent: 03 August 2006 15:29
To: Radiance general discussion
Subject: RE: [Radiance-general] making my own ies file

Hi Dave

yeah i know what type of lamp, it was in the last email i wrote to
christian, its a 4000w fresnal lens spotlight from Arri. how do the mean
and initial lumens value help me? do i use one of them in the 'lumens
per lamp' value for the ies file

thanks chris

-----Original Message-----
From: [email protected] on behalf of J. David
Maino
Sent: Thu 8/3/2006 2:09 PM
To: Radiance general discussion
Subject: Re: [Radiance-general] making my own ies file

If you know what kind of lamp you want to use, you can go to philips or
ge's website and find the
lamp there. They should have the mean and initial lumens listed that you
can then put into your IES
file. For the ballast factor, you can use 1, or you can go to a site
like advancetransformer.com and
find a ballast that will work with whatever lamp you've chosen and use
that ballast factor (although
generally you can find a ballast for your lamp that has whatever ballast
factor you want, so you
could probably just set this at whatever you want it to be).

Dave

Chris Foster wrote:

Hello again,

Im making my own ies file for a spotlight i am using in a lab from

data

i found at the manufacturers website. i have a graph of angle against
brightness and i know the format of such a file from readin RwR.

however

i can seem to find a description for some of the values needed, either
in the book or in the online manuels

the file i have made so far looks as so, but the text in square

brackets

are the values im not sure of (ignore the oridnary parenthesis, i

simply

havent measured my spotlight yet.). i havent got access to the iesna
standard and so was wondering if anyone on the list has knowledge of
this area.

TILT=NONE

1 [lumens per lamp] [candela multiplier] 11 [photometric type] [units
type] (w) (l) (h)
[ballast factor] 1 4000
0 0.5 1.5 3 4 5 6 7.5 9 11 17
0
1880000 1800000 1600000 1000000 600000 400000 250000 120000 100000

60000 0

i think that all the square bracket values have to be 1, but the one

im

most unsure of is the lumens per lamp value. this is most definately

not

1, does anyone know what this is and how i calculate this for my

spotlight??

thanks in advance, any help much appreciated as usual (wish i could

give

something back!).

Chris

p.s. still havent solved my last email either if anyone has any
suggestions...

-------------------------------------------------------------------
This e-mail and any attachments may contain confidential and/or
privileged material; it is for the intended addressee(s) only.
If you are not a named addressee, you must not use, retain or
disclose such information.

NPL Management Ltd cannot guarantee that the e-mail or any
attachments are free from viruses.

NPL Management Ltd. Registered in England and Wales. No: 2937881
Registered Office: Serco House, 16 Bartley Wood Business Park,
Hook, Hampshire, United Kingdom RG27 9UY
-------------------------------------------------------------------

------------------------------------------------------------------------

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

_______________________________________________
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-------------------------------------------------------------------
This e-mail and any attachments may contain confidential and/or
privileged material; it is for the intended addressee(s) only.
If you are not a named addressee, you must not use, retain or
disclose such information.

NPL Management Ltd cannot guarantee that the e-mail or any
attachments are free from viruses.

NPL Management Ltd. Registered in England and Wales. No: 2937881
Registered Office: Serco House, 16 Bartley Wood Business Park,
Hook, Hampshire, United Kingdom RG27 9UY
-------------------------------------------------------------------

***********************************************************************************
This e-mail, (and any attachments) is confidential and may be privileged. It may be read, copied and used by the intended addressee only. If you have received this in error please contact BDP immediately.

If you have any queries, please contact the sender.
***********************************************************************************
Building Design Partnership
Registered in England No 2207415:
Registered Office: Building Design Partnership Ltd, Sunlight House, PO Box 85, Quay Street, Manchester, M60 3JA, http://www.bdp.co.uk
***********************************************************************************

10

Hi Chris,

I believe the <lumens per lamp> field is used to calculate fixture
efficiency (notice it is lumens per lamp, not total fixture lumens). If
you are not concerned with fixture efficiency, put any value you like
there. Osram HMI 4000 W/SE has a total lumen output of 380,000 lm, if
you'd like to have a realistic number there anyway.

Most photometric viewers can calculate the lumens out of a fixture
easily. I plugged your file (with an arbitrary number in the lumens per
lamp field) into a program called Photometric Viewer (from Acuity
Brands) and it showed the fixture to output 37,982 lumens. Based on the
number of lumens coming out of the Osram lamp, that would be about a 10%
fixture efficiency. Seems low, but then again, I don't know what a 4000W
Metal Halide fixture looks like anyway.

Hope that helps.

Halley

11

From Rob Guglielmetti, who isn't able to get through to the list at the moment...

···

Subject: Re: [Radiance-general] making my own ies file
Date: Thu, 03 Aug 2006 10:12:00 -0600
From: Rob Guglielmetti <[email protected]>
To: Radiance general discussion <[email protected]>

Chris Foster wrote:

Hi Dave

yeah i know what type of lamp, it was in the last email i wrote to christian, its a 4000w fresnal lens spotlight from Arri. how do the mean and initial lumens value help me? do i use one of them in the 'lumens per lamp' value for the ies file

Hi Chris, et al.:

Chris, the fresnel lens has nothing to do with the lamp. Just want to be clear on that. The lens is part of the luminaire itself and its behavior should be accounted for in the candela values you got from the website. Arri makes luminaires, not lamps. (And that 4K fresnel is a kick-butt luminaire!! I used their 2K spots in my theatre days; those 4K's must _really_ throw some light. The lamp socket for the 2K was nuts, with its own mechanical clamp that held it in place. I still remember the lamp code: CYX. Don't ask me why that tidbit remains in my brain sixteen years after the fact, when I can't even remember what I had for dinner last night. Anyway...)

The lumens/lamp field really should contain the initial lumens of the lamp used in the luminaire when it was photometered, per the specification. That's just good practice in case someone else ever uses that file and they have a different lamp; that way one can tailor the output to reflect a different lamp output using the multiplier (see below). The fact of the matter is that in Radiance (and I'm pretty sure this is true of AGI as well), it really doesn't matter what you put in the lumens/lamp field in the ies file, as the candelas are what they are, regardless. Like I said, it's just good practice to follow the spec. That said, in Lightscape, if you changed the lumens in that field, you changed the output of the luminaire, but this is not really the way things are supposed to work. That's what the multiplier is for. The multiplier field allows you to adjust the luminaire output to reflect a different lamp output, as well as the effect of all the other elements that go into the Light Loss Factor (LLF).

This brings me to mean vs. initial. Lamp catalogs usually have both values, the mean value quantifying the lamp's lumen depreciation over time. It's nice to have both because then you can compute more accurate LLD multipliers (mean lumens/initial lumens=LLD), as they vary from lamp type to lamp type, and manufacturer to manufacturer. Of course LLD is only one element of the total LLF.

Note also that ies2rad has its own multiplier (-m), so you could leave the multiplier in the ies file at 1 and use the -m to apply your multiplier (this is what I do).
- Rob Guglielmetti
www.rumblestrip.org

12

Hi all,

I've never had so many ppl help on a subject, thanks alot rob, halley, thomas, dave and christian. very much appreciated.

Dave and rob you both talk about a light loss factor, as a multiplier, i gather you mean the candela multiplier field in an ies file. no need to reply if im right...just please tell me if im wrong! i'll just leave this as 1 and then use the -m option if needed.

ill use the 380,000 lumens in my lumens per lamp value then, although by the sounds of things its not crucial what i use.

thomas - i was aware that my terminology was mixed up, but now its not-thanks. got a copy of that lamp now thanks.

halley - i think that 38000 fixture output is a bit low, the efficiency should be higher.but ur information helped, thanks.

rob - they do really throw out some light. from about 2m away we got about 100k lux. after using all of them (we have 5) for a couple of weeks some bright spark mentioned that we may be gettin a little bit too much UV so we had them tested. a single one from 2.5m away is above UV radiation safety standards after 20 mins, we had all 5 pointed at us from about 2m away, meaning we were only safe under their collective glare for 4 mins. we would spend all day under them......whoops. needless to say we installed some UV filters afterwards. yeah i presumed that the fresnal lens was taken into account already with the photometric data, dont know why i mentioned it really, but thanks anyway for confirming my suspicions :wink:

so my 2 final ies file will look as below,

spot.ies

TILT=NONE

1 380000 1 12 1 1 2 -.376 0 0
1 1 4000
0 0.5 1.5 3 4 5 6 7.5 9 11 17 90
0
1880000 1800000 1600000 1000000 600000 400000 250000 120000 100000 60000 0 0

flood.ies

TILT=NONE

1 380000 1 14 1 1 2 -.376 0 0
1 1 4000
0 7 10 13 16 22 26 30 36 40 44 50 60 90
0
176000 166000 168000 168000 160000 148000 142000 120000 44000 12000 6000 2000 0 0

if anyone see's anything wrong with these please shout at me!

thanks enormously

chris

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13

Chris Foster wrote:

Hi Dave

yeah i know what type of lamp, it was in the last email i wrote to christian, its a 4000w fresnal lens spotlight from Arri. how do the mean and initial lumens value help me? do i use one of them in the 'lumens per lamp' value for the ies file

Hi Chris, et al.:

Chris, the fresnel lens has nothing to do with the lamp. Just want to be clear on that. The lens is part of the luminaire itself and its behavior should be accounted for in the candela values you got from the website. Arri makes luminaires, not lamps. (And that 4K fresnel is a kick-butt luminaire!! I used their 2K spots in my theatre days; those 4K's must _really_ throw some light. The lamp socket for the 2K was nuts, with its own mechanical clamp that held it in place. I still remember the lamp code: CYX. Don't ask me why that tidbit remains in my brain sixteen years after the fact, when I can't even remember what I had for dinner last night. Anyway...)

The lumens/lamp field really should contain the initial lumens of the lamp used in the luminaire when it was photometered, per the specification. That's just good practice in case someone else ever uses that file and they have a different lamp; that way one can tailor the output to reflect a different lamp output using the multiplier (see below). The fact of the matter is that in Radiance (and I'm pretty sure this is true of AGI as well), it really doesn't matter what you put in the lumens/lamp field in the ies file, as the candelas are what they are, regardless. Like I said, it's just good practice to follow the spec. That said, in Lightscape, if you changed the lumens in that field, you changed the output of the luminaire, but this is not really the way things are supposed to work. That's what the multiplier is for. The multiplier field allows you to adjust the luminaire output to reflect a different lamp output, as well as the effect of all the other elements that go into the Light Loss Factor (LLF).

This brings me to mean vs. initial. Lamp catalogs usually have both values, the mean value quantifying the lamp's lumen depreciation over time. It's nice to have both because then you can compute more accurate LLD multipliers (mean lumens/initial lumens=LLD), as they vary from lamp type to lamp type, and manufacturer to manufacturer. Of course LLD is only one element of the total LLF.

Note also that ies2rad has its own multiplier (-m), so you could leave the multiplier in the ies file at 1 and use the -m to apply your multiplier (this is what I do).

- Rob Guglielmetti
www.rumblestrip.org