Light Meter

A Light Meter is a tool used by the Gaffer and Director of Photography to measure the intensity of a source of light.

• Pre Lighting a Set

Using the light meter in the absence of the camera to make sure the lighting design of the set is in the ball park of the needs of the camera.

• Understanding Fixture Intensity

Measuring the output of a light to understand its capabilities in relation to exposure.

• Consistency in Lighting

Using the light meter to make sure elements of the lighting design are consistent between shots of a scene.

Camera Settings

Before you begin to use your meter you'll need to know the camera settings selected by the DP.

• Frames per second

Doubling FPS increases light needed by 1 stop, halving FPS decreases light needed by 1 stop.

• ISO

Also called ASA. Doubling ISO decreases light needed by 1 stop, halving ISO increases light needed by 1 stop.

• Shutter Angle/Speed

Doubling Shutter decreases light needed by 1 stop, halving Shutter increases light needed by 1 stop.

• Filter Compensation

There are many different types of filtration that the camera uses and dpending on the type, they affect the exposure of the image.

Methods of Reading Light

Incident

Measuring light that is fallng onto the subject. Metering with the dome in can give you a specific reading of a light.

• Keep your body / shadow out of the reading area

Do not obstruct light that you are metering with your body.

• The manual states you should not put it in an intermediary position

This will change the quality of the light and produce an incorrect measurement.

Reflective

or Spot Metering is used when measuring the light reflecting off of the subject.

• Select Spot Meter

Turn the eye piece to the spot meter function.

• Aim Spot Meter at Subject

Fill the entire viewing area with the subject you want to take a reading of and meter off the most evenly illuminated area. Take this measurement at the same axis and distance that the camera is or will be.

• Block out Light Leaks

Block off extraneous light entering the meter through the viewfinder by your eye, either with a cupped hand or with the aid of an eyecup (Nikon DK-7 eyecup is useful).

• Hold Meter Steady

for a few seconds after taking the spot reading reading.

• Release Trigger

Take care to let go of the measuring trigger before swinging the meter away to read the measurement. Pulling the meter away from the subject too quickly will result in measurement inaccuracy.

Lighting Ratio

The relationship between intensity of the key light to the fill light. Measuring each source can tell you about the relationship.

• 1:1 Ratio

The Key and Fill source are at the same intensity.

• 2:1 Ratio

the Key light is twice as bright or 1 stop brighter than the fill

• 4:1 Ratio

The Key light is 4 times as bright or 2 stops brighter than the fill

Using Sekonic 858D-U

There are a few settings you should take advantage of while using this meter. For all of these you should make sure you have the latest firmware version on your meter.

• Hold down the menu button to lock the touchscreen control. To unlock you'll hold down the menu button again.

This will prevent you from making unwanted changes to the meter.

• Switch Measure/Memory Buttons for Spot Mode

While the measure button is in an intuitive spot for the incident mode, the standard measure button for reflective mode can be difficult to remember.

You can change this in the menu by clicking Menu > Custom Setting > Switching Measure/Memory Buttons > Auto (Incident: Standard, Spot: Reverse)

• Change Custom Button 2 to Memory Clear

This will give you very quick access to clearing your memory as usually you have to click into the menu, click down a page, then click the memory clear. You can do this by clicking Menu > Custom Setting > Function Button - 2 > Scroll Down > All Memory/Multi-Clear. To change the incident/spot now you will go into the Wrench > Incident/Spot > Select your mode.

These settings will make it easier to figure out the difference in exposure between multiple measurements.

• Set Analog Scale to EV Scale

This will make it so that the scale you see at the bottom of your meter is measured in full stop differences and will not show you the stop differences. For example if you take a reading it will show you that you are 2 stops under.

• Set Mid-Tone Value

The Mid-Tone value is basically your exposure. This will help you in various ways to see the range of your exposure. If you make use a custom camera profile for your meter it will display the dynamic range in your analog scale at the bottom once set.

This can be found in the Toolbox (Wrench Icon) > Set Mid-Tone. Most of the time you will do this from your current measurement, but say you are in a dark room and you want to set your midtone to a 2.8 at that time, you can set it to whatever value is acheivable, then go to Toolbox > Set Midtone > Modify Current Mid.Tone and then you can adjust it to 2.8 from there.

• AVE/ΔEV Function

This function allows you to do two different things, one of which we will not use. The first thing it allows you to do is take multiple meter readings and then average them together, in order to do this you have to take multiple readings, set your memory for each one, then hit this button. Then it will display the average amongst all those values.

This is not very useful for us, but the ΔEV function is, as it allows us to much easier figure out the ratio between our key and other exposures. To use the function you'll do the following:

• Make sure your memory is clear

• Take a meter reading that is equal to your current stop on your camera. You don't want to meter your key light as that could already be in a wide variety of places against your cameras exposure.

• Click the AVE/ΔEV button. This will set your stop and it will appear in yellow (on 858D-U only)

• Take meter readings as normal now, it will show you EV values (stops) difference in light. So you can meter your fill side and see that it is 3 or 4 stops under without having to do the math.

This also works the same using a spot meter reading, the same steps must be followed. The only downside to this is when you change from incident to spot, the ΔEV value resets and must be set again.

This could also be very helpful to figure out filter compensation if you are trying to figure out how many stops a filter cuts.

• Uncheck all of the Excess Standard Filters and add your own

Most likely there are a few filters commonly used, but remembering the compensation for them can be difficult. First, go to Menu > Edit Filter > Now uncheck everything you will not use and check a few of the User Filters

Now Click on the User Filters and type in whatever filters you commonly use along with their compensation. One idea is to put in the difficult to remember Sony ND filters 1/4, 1/8, 1/16, etc. and their corresponding compensation.

• Exposure Profiles

This is a much deeper segment and can be viewed in this article. Calibrating Light Meter

• Additional Data - Show Footcandles

It can be helpful to know roughly how many foot candles are needed for a given exposure. You can go into the menu and display footcandles at all times by clicking Menu > Custom Settings > Additional Data > Illuminance

You will also have to go to Menu > Custom Settings > Illuminance/Luminance Data > Foot Candle. This will have it display as foot candles and not lux.