Needed Light Levels?

[RyanT]

Someone had a pretty good question on here a while ago and it was sad to see it go down to the bottom of the bunch without being answered.

Anyways, the question was is there a formula or something that will tell you how much light you need at a given film speed and certain distance?

For example, say I'm lighting a sidewalk at night and I want to do it with one light overhead. My HVX has an estimated film speed of around 300asa and I'll have the light 15 feet up. How many watts do I need in order to get a proper exposure?

Anybody care to share the answer to this one?

 

[Shooter]

I dont think there is a basic formula for this because of various efficiencies of diferent lighting units.

You need to factor in f/stop also

You could bone up on foot candle readings though. Many professional lamps publish the foot candle reading.

Maybe simpler for you to do a couple of tests with a couple of lamps at night.

BTW - my rule of thumb is start with too much light.

 

[RyanT]

The foot candle reading could be helpful, I'll have to look into that.

 

[Beat Takeshi]

I guess it depends on what look you are going after. When we shot Mordere we used a 2K up high with light diffusion to make a spot on the ground and then we used a 1k softbox and a 300w for highlights and smoother fill. For a bigger area I can see a 5k or a few 1ks sread out a little being effective.
Here are some BTS of it.
http://mikeks.smugmug.com/gallery/6236644_hsFtn#301098704_DzfMx

 

[schmedel]

I would like to know also.

I found this- www.nightscaping.com/pdfs/nightchart.pdf

But I have no idea what it means- or what it will do for me