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#1 Matheus Pereira

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Posted 20 May 2016 - 02:13 AM

Hello everyone, this is my frist topic here and before I ask my question I'd like to say that Im very glad to be part of such an amazing network and I hope to get a lot of knowlege here and perhaps someday I'll be able to help others too.

Im quite interst into cinematography and i've been styding it for a while. I have already studied direction and nature of light. The types of light (key, fill and back light). Diffusers. Color Temperature. White Balance. Gels and filters. Exposure. Light ratios. Painters and other cinematographers.

But I've been having trouble to understand a few things, I hope someone could explain them to me.

I know there are HMI, tungstein, flourescent and led lights. I want to know how to choose properly the wattage and what light (fresnel, kino, PAR etc) to key, fill and back. I mean, how do I choose the light and wattage right for each occasion (documentary, fiction, outdoor/indoor at night and day, etc) and position.

I know this is a dumb question, but I really dont know this, how to choose what light and the wattage right. If someone could explain this to me please, at least an overall explanation. And also if this is not too much tell me what else I could study in order to understand better all this.

Again, sorry if this question is too stupid or if I couldnt ask it right, Im still learning.

Thanks and cheers from Brasil!
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#2 Brian Drysdale

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Posted 20 May 2016 - 03:40 AM

It's not a stupid question, it gets you started on one of the things you need to know when doing more than basic lighting.

 

A good starting point are the photometric calculators or the charts provided by the light manufacturers. Find out the amount of light required for a particular stop at the ISO you're using and you can work it out.

 

http://calc.arri.de/calculator

 

They also have an app.


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#3 John E Clark

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Posted 20 May 2016 - 12:25 PM

Hello everyone, this is my frist topic here and before I ask my question I'd like to say that Im very glad to be part of such an amazing network and I hope to get a lot of knowlege here and perhaps someday I'll be able to help others too.

Im quite interst into cinematography and i've been styding it for a while. I have already studied direction and nature of light. The types of light (key, fill and back light). Diffusers. Color Temperature. White Balance. Gels and filters. Exposure. Light ratios. Painters and other cinematographers.

But I've been having trouble to understand a few things, I hope someone could explain them to me.

I know there are HMI, tungstein, flourescent and led lights. I want to know how to choose properly the wattage and what light (fresnel, kino, PAR etc) to key, fill and back. I mean, how do I choose the light and wattage right for each occasion (documentary, fiction, outdoor/indoor at night and day, etc) and position.

I know this is a dumb question, but I really dont know this, how to choose what light and the wattage right. If someone could explain this to me please, at least an overall explanation. And also if this is not too much tell me what else I could study in order to understand better all this.

Again, sorry if this question is too stupid or if I couldnt ask it right, Im still learning.

Thanks and cheers from Brasil!

 

The problem is a bit more complex than asking 'what wattage'... the ARRI site mentioned will give information on ARRI lights, and these are usually expensive but are also usually part of a rental house's set of options.

 

In any case, the 'wattage' of a light does play a part in determining how much light is delivered to the subject, but just wattage alone does not give the full story. The light 'housing/reflector/lens' shapes the output light and must be taken into account. Hence the use of the ARRI calculator... as it is a pain to calculate from general principles.

 

If you can't afford ARRI or even renting them... what would be 'best' is if you can find a sympathetic peson at a rental house in your area, and with a light meter set up some 'cheaper' offerings, and determine the light delivered to the subject.

 

There are Lowel light packages that are cheaper than ARRIs... but also may be less robust in usage... but may be good enough for your learning needs.

 

Here's a web site that has a table listing a number of lighting manufacturer's products, ARRI, Mole-Richardson, Lowel, and others, and list their photometric data... that is how much light is delivered to the subject at a given distance (in the case of the table, all lights were measured at 20 ft (6 or so meters).

 

http://wolfcrow.com/...t-one-tungsten/


Edited by John E Clark, 20 May 2016 - 12:25 PM.

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#4 Tyler Purcell

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Posted 20 May 2016 - 03:07 PM

But it also has to do with the look you're trying to achieve.

You may want a hard/bright backlight, but not much key or fill.

The key for ME at least, is to measure things on set based on LOOK, rather then just tables.

Every type of light has it's purpose, building your truck based your needs for a specific show, is based on experience that's hard to quantify in a table.

I wish there was a 3d program that allowed you to place lights, camera, set lenses, stock/imager and everything for a given shot and balance it all out before going to set. You can do the math for sure, but it would be nice to have a program.
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#5 David Mullen ASC

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Posted 20 May 2016 - 03:09 PM

I learned like most people starting out, I got a light of "X" wattage and design and figured out what it could and its limitations were. Once you get to know a 650w tungsten fresnel (aka "Tweenie") it's not hard to figure out what something twice (or half) as powerful will get you.

Most beginners work with lamps in the 20 amps and under range just because those can be plugged into most household circuits. So at the upper range you have the 2K tungsten fresnels & open-faces, and the 1.2K and 1.8K HMI's. But at some point you have to figure whether you need more lights with smaller wattages or fewer lights with higher wattages because of the limitations of household power distribution. And that depends on what you are trying to achieve.
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#6 Jan Tore Soerensen

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Posted 21 May 2016 - 07:19 PM

I learned like most people starting out, I got a light of "X" wattage and design and figured out what it could and its limitations were. Once you get to know a 650w tungsten fresnel (aka "Tweenie") it's not hard to figure out what something twice (or half) as powerful will get you.

Most beginners work with lamps in the 20 amps and under range just because those can be plugged into most household circuits. So at the upper range you have the 2K tungsten fresnels & open-faces, and the 1.2K and 1.8K HMI's. But at some point you have to figure whether you need more lights with smaller wattages or fewer lights with higher wattages because of the limitations of household power distribution. And that depends on what you are trying to achieve.

I have actually figured out this the hard way. So our next investment is a generator, so we can have enough power on set.

 

Another huge factor is not having to choose location based on availability of power.


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#7 Phil Connolly

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Posted 04 June 2016 - 06:52 AM

I started out with a set of 3 x 800w red heads and spent about a year just experimenting with them (not full time but quite a bit). Initially my stuff looked terrible - then I learn't to control them a bit better. Bouncing, using gels and pushing them to the limits. On subsequent films I would hire in different fixtures - and my knowledge and experience would  grow. 

 

After the red heads I tried different size Fresnels and larger 2K blonds, then I started using HMI's, then Kino's and now LED's. With me it wasn't about trying to learn everything all at once. But using a bit of kit experimenting then trying something else. 

 

In terms of wattage you start to get a feel for it and now I can normally guess fairly accurately what size I need for what job. With LED's and Kino's its less about the wattage and more about the size of a fixture. But when you start - the best approach is to set up the camera, set up some lights and have a look. The more you experiment the better your understanding will be. A trial and error approach is fine in digital, you have a monitor so you can set something up and see if you like it. As I got more experienced I mainly got faster as I could set stuff up and predict the outcome better. When I was starting out you'd set something up, then change it a few times till you got it to work.

 

When I teach lighting I give my students exercises - where we set up a shot and a situation and experiment with different looks and lights to see what the options are. Taking the time to play around is key. A few tunsten fixtures, some bounce material (e.g polyboard), some diffusion and CT gel's will allow you do a lot.  

 

A mistake people often make when they start out is over lighting, too muck light added with multiple shadows. Look at what your getting with the available light, the augment it subtly only if you need too.

 

In terms of working within the available power, HMI, Kino and LED will give you more light output for a particular wattage then tungsten. So if you limited to domestic power using these sources will help you do more - but they are more expensive to rent then tungsten, so it might be easier to use a generator. Its not too bad in the UK since you can plug a 2.5k HMI into domestic mains. If I've got enough money for Kino's and HMI's I can normally do quite a lot with domestic mains. Recently I've only really needed to use generators for exterior shooting.  


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#8 Alexandros Angelopoulos Apostolos

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Posted 05 June 2016 - 01:18 AM

I was going to ask why is it that film lights are always described in terms of power (wattage; thankfully, watts are a SI unit – we didn’t need another imperial one, or from any other unit system) and not in lumens or luxes.


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#9 Brian Drysdale

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Posted 05 June 2016 - 06:03 AM

I guess it's because the power requirement is the first thing you need to know when rigging lights.


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#10 David Mullen ASC

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Posted 05 June 2016 - 09:16 AM

Power requirements and tradition -- most theatrical and stage lighting has been tungsten for more than a century, so the connection between wattage and output was easier to understand.  The EU only mandated the lumens label for lights in 2010 because of the emergence of compact flos and LED bulbs.


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#11 John E Clark

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Posted 06 June 2016 - 11:38 AM

I was going to ask why is it that film lights are always described in terms of power (wattage; thankfully, watts are a SI unit – we didn’t need another imperial one, or from any other unit system) and not in lumens or luxes.

 

Watts is the 'easiest' parameter to determine... when it comes to lumens there are conversion factors for various light production technologies, such as traditional tungsten and it yielding 1700 lm per 100 Watts.

 

The problem then is what is the 'light beam' shape... for a free standing bulb the 'shape' is approximately omnidirectional, and so one would calculate the Lux/Footcandles by dividing 1700 lm  by 4*pi*r^2. That is the surface area of the sphere surrounding the bulb at distance 'r'.

 

With modifiers like reflectors or lenses, more of that 1700 lm may be directed to the subject... or at least the area of the subject, but alas, that takes even more math than the simple omnidirectional case...

 

Better to either get the manufacturer's specs... or go to a rental house and meter various lamps and housing arrangements...

 

That of course is also without regard for the spectrum of the light...


Edited by John E Clark, 06 June 2016 - 11:40 AM.

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