Tuesday, March 15, 2011

Light Painting White Balance

Last week I got some lovely new flashlights from a WootOff.  I'm not sure the brand or maybe they just don't have a brand, but they are 3 watt, chip LED and although they don't have focus adjustment, they are pre focused beautifully.  While adapting one of them for my LP filter system I notice the large disparity in white point across the selection of LED flashlights I use.  Of course I have long used and known about the white point difference between the LED and Incandescent  lights I use, but there is quite a range even among the similar light sources.  I decided to inventory it a bit and just make sure I knew better what I have been working with.  Also thought it might make an interesting blog post for the more geeky photog types who may or may not ever read this blog.. lol  

I perceived a greeter degree of difference in color temp with my eyes then the camera recored.  But I tried to take some pictures to illustrate the differences.  I actually paint with several other lights, but theses full sized flashlights are my main lighting choices.  

The Line Up:

left to right : 
4D Xenon Incandescent MAG-LITE  (focusable)
3D Xenon Incandescent MAG-LITE  (focusable)
2 x 3D Krypton Incandescent MAG-LITE  (focusable)

2D LED CHIP MAG-LITE (Seems like about 1.5 Watts)  (focusable)
2D New Woot Special Mystery LED 3 watt
2X 2D Old Woot Special Brinkman (seems to be about 1.5 watts)
Note the these two are the same brand and same age but have a large white point difference… Hmmmm
3AAA LEDLENSER (not compatible with my LP filter  system, but I use it a lot so I included it to compare)  

Incandescents - Tungsten WB
Flash WB
Fluorescent WB
Saturation Enhanced to show the difference more clearly.

I tried several camera setting white points to try to illustrate the color differences, and also boosted the vibrance of one test to really show it.  I know it still seems a bit subtile, but I've noticed the effect before in finished work.  

As for the Incandescents, I can see that the Xenon Incandescent are somewhat cooler in color temp then the older Krypton bulbs.  When using a red or warm gel the small brightness advantage the Xenons provide is likely null.  I suspect the bulbs produce about the same amount of red, and the brightness difference is made largely in the cooler side of the spectrum.   

The LEDs on the other hand are all over the map.  Some are very magenta and some a bit green.  Since adding LED flashlights to my arsenal, I have usually chosen them when using a blue gel, because the incandescents contain so little blue that they don't provide enough brightness.  The opposite can be true for red gels as well, the LEDs have little red.   The white point difference between the Magenta tinted ones and the Green tint is not that much really, but it's more then enough when not gel'd to give an unfortunate green cast that may have consequences to correct with a overall image white point adjustment in post.  


I have in the past usually set the camera for Incandescent white point when light paining.  Usually the 4D MAG-LITE is my 'main' light, so that does a good enough job of getting it to be white for the camera.  After this examination however I have decided to toy with setting a white point for the new wootoff flashlight.  This gives me warm tones from the Incandescent which is a nice option, as the red gels look very good in this color space..  Which begs the question, what is the white space of the LED lights?  Well not that surpassingly its a little unique.  Most White LEDs are technically fluorescent so that works out kinda ok, and there are pretty close to flash, so that works ok too.  It's really just important to that the camera preview is close.  I know I could do a custom white balance, but I'm lazy and I'll make the white point where I want it in post anyway.  

    Maybe I'll just work in B&W and forget it.. lol
A reject image that I kinda still love from last Sundays shoot (Model Brooke Lynne)