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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

I oftne see DP's using china balls or space lights to bring up the ambient light in the room. Essentially, bouncing a light off the ceiling (I assume) does the same thing. I've been bouncing to bring up ambient but considering china balls. What are the advantages, if any, of using a china ball instead? Just that you have more control over the spill/throw by adding skirts? Is there any difference in the quality of light that is put out?