Manipulate Light Maintaining Exacting Control

Hi and welcome to my blog.  Today I want to follow up on the topic I posted yesterday.  Yesterday I went deeper into lighting that most care to understand, today I want to explain how to achieve the controls I spoke of.  If you are reading this, I will assume you are one of the people that really want to know how to gain control over your lighting, so I will tell you how to…it’s simple math.  If you can add and subtract you can control your lights.

To apply this simple math to gain control over your lighting, you will need the proper tools. In this case, you will need a light meter. I recommend a light meter that has a spot meter built in. It will save you a ton of frustration, trust me. With a spot meter, whatever you point it at and make a measurement of, the reading produced will tell you what 18% grey is.  Knowing where 18% grey is exactly, is like knowing one of the two variables required to solve any math problem.  This 18% grey measurement is the constant and is the value that never changes.

Here is an example; if you have a strobe set to 1/4 power and you take a spot measurement, then apply those settings to your camera, whatever was measured, a black piece of paper or a white piece of paper will now be an exact shade of grey - 18% shade of grey in the resulting image.  Now set the power to 1/2 and the resulting image will not be 18% anymore, it will doubled in value.  This will be a 36% grey (a lighter shade of grey).  Next, power up to 3/4 power and make a picture.  The resulting image will yield a grey that will be a 72% grey (white with detail).  Now go to full power and what is the result?  It is a 144% grey or blown out white with no detail.  Heck 100% is white with no detail.  There is never a need to go to 144%, it’s just a waste of power.  Now do the same test, but power down the strobe.  Start at 18% and power down one stop at a time and you will end up at black.  Count the stops it takes to get to black.  Now you have a system of known values, that will allow you to achieve predictable and repeatable results.

Lets look at the power adjustment for a minute.  On the big strobe or a speedlite, if you go from 1/4 to 1/2 power you just doubled the power, or in simple terms you just increased the flash power by one stop.  A stop is a stop is a stop.  It doesn’t matter if you gain or lose a stop from a power adjustment, ISO, shutter speed or aperture they are all equal and are considered a reciprocal.  Reciprocals are the same with flash power, as they are with anything in the photography system.  You can give here and take there, it is all the same, well, except for the artistic result specific settings yield.

So where does photographic white live exactly?  That can be at 2 1/3 -2 2/3 stops above 18% grey. The exact number all depends on the cameras sensor dynamic range, or the characteristics of film base you are using.  That is if you still shoot film, like I do.  So where does Black (photographic black) live?  It is 4 2/3 stops under 18% grey?  It is so simple to do the math, there is no need to guess if you are going to make a picture with a black background or a white one, or any shade in between.  Add color gels and use the same power controls now you have a complete system of control that you can reproduce at anytime.

Below is a video to show you how I can turn a black piece of paper into a white piece of paper.  I do it with a single frame and never guess.  I promise you a whole new world of photography awaits those that want to take control.  The right tools, a little bit of math, and you can create any color, any shade, any tone, any vibrancy that you can dream of. The best thing is you never ever have to guess again.

The video is a pretty bad.  The room is very dimly lit so I increased the video brightness in post.  This made my face look like I have a skin condition, and added 50lbs to my face, DOH.  The information is good, and to me, that is all that matters.  If it wasn’t 1:30am after a long day of work I would remake the video.  I hope you can forgive my appearance and take from this video, the information that will help you control light. I hope you all have a great day.  Thomas Shue