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Hi,

We are two technicians working in the film industry in France (a grip guy and a gaffer) and we just discovered this very interesting forum.  We particularly noticed that gaffers and cinematographers were asking questions about light output and what aperture is obtained at a certain distance. It happens that with the help of two IT engineers we developed an iOS app responding to this question about 2 years ago.

First and for all, we’re not going to post messages everywhere on this forum to sell our app nor are we going to pollute your threads to gain in visibility. We just think some of you might be interested in what we created and since we’re a really small team working on off-time we can’t do any real advertising, so you probably wouldn’t know our app existed.

Our app is called Predilux (for pre-diction and lux for light) and predicts the exposure as measured by a light meter, by choosing a light source and a distance. Or inversely predicts the distance to the light source by specifying the exposure.

Predilux takes into account:

  • Camera settings (FPS, ISO, Shutter angle)
  • Source settings (Focalisation, Lenses, Grids, Dimmer, CCT, etc)
  • Gels mounted on or close to the source (All ROSCO e-colour+ range)

All results have been experimentally verified by us with a light meter in rental houses. For each source setting we made several measurements at different distances and this took a lot of time. So Predilux does not rely on constructor’s data, but on real data reflecting the state of the equipment as found in rental houses. Our data sometimes differs from the constructor’s data.

Here is a quasi exhaustive list of the sources measured and included in the Predilux (12/2019) :

Tungsten

  • ARRI 150, 300 Plus, 1K Plus, 5K Fresnel, T10, T12, Rubylight (MFL lamps)
  • Briese 77, 100, 140, 180 with lampes ranging from 650 W to 2K
  • Mole Richardson Softlite 1K, MaxiBrut 16 (MFL lamps)
  • Openfaces such as Redhead, Blonde, Desisti Renoir 5kW and LTM Cyclight 2K
  • ETC Source 4,  Dedolight, Zaplight, CMC 20K, etc.

 HMI

  • ARRI  AS 575, 1200, 4K, 6K, 12K, Arri M18, M40, M90, ArriMAX 12K & 18K
  • K5600 JokerBug 200, 400, 800, Alpha 1600, 4K, 9K, 18K
  • AFM 575, 1200, LTM Cinepar 2.5K

Fluorescent

  • KinoFlo 2ft, 4ft & 6ft

LED

  • ARRI S30, S60, S120, S360
  • KinoFlo Celeb 200, 250, 400, 450, 850
  • DMG SL1, SL1 mini, SL1 Switch, MaxiSwitch
  • Mole Richardson Tweenie, Senior, Tener
  • Aladdin Biflex 1x1, 1x2, Flexlite 1x4, 350
  • Dedolight bi90, Cineroid LMD400, Velvet V1

Balloon

  • Airstar Gaffair 1200, Elipse 4000, PAD 9ft x 9ft, Tube 16K

If any of the administrators of this forum wish to try out our app, we would be happy to give them one or several free life-time activation codes. For all the other users, our app is available on the Apple Store (). An Android release is planned.

If you have questions or requests, don’t hesitate to contact us at this address predilux@wid.la

Thanks for reading this post and we hope you thought it was interesting,

Georges Harnack for the Predilux Team

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I just bought it after seeing Luke Seerveld talk about it. I think it is quite a cool. 

I'd like to see it developed further, but it is definitely a cool start. 

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On 2/2/2020 at 3:49 PM, Tim Pfautsch said:

Is there an Android version planned? Sounds very useful.

Hello Tim,

An Android version will be available in the upcoming months.

Thank you for your interest in Predilux ! 

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13 hours ago, Joshua Linder said:

I just bought it after seeing Luke Seerveld talk about it. I think it is quite a cool. 

I'd like to see it developed further, but it is definitely a cool start. 

Thanks a lot Joshua ! 

Here's the video by the way

 

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1 hour ago, Georges Harnack said:

Thanks a lot Joshua ! 

Here's the video by the way

 

I've got a few questions on it. I sent them to your website's email. but just in case
1. will you be adding quasar, DS, SGC, Creamsource, or HIVE lights to it
2. i think the lightstorm 300d might have an error
3. could you show the output numbers so we can compare ours
4. will you be adding the output from LEDs' builtin gels

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On 2/15/2020 at 1:24 PM, Joshua Linder said:

I've got a few questions on it. I sent them to your website's email. but just in case
1. will you be adding quasar, DS, SGC, Creamsource, or HIVE lights to it
2. i think the lightstorm 300d might have an error
3. could you show the output numbers so we can compare ours
4. will you be adding the output from LEDs' builtin gels

Hello Joshua,

We just added Astera AX1 and Titan tubes (Predilux version 2.1) and fixed an error with the Aputure Lightstorm 300D - sorry for that, it was a database error, not our measurement procedure. Other fixtures are coming up, based on user demands; Quasar and Dgital Sputnik are planned.

Our data is available in the Predilux app, for the moment only in T-stops/Aperture, but soon we'll also output in lux and foot-candle. 

Builtin gels is a lot of work to measure!

Kind regards, Georges Harnack

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