There’s two ways you can begin to light with strobes: 1.) Set up your strobe and modifier, then test-fire some shots to evaluate your exposure. 2.) Use a flashmeter to pre-light your set-ups for faster, more accurate, and most of all, more repeatable strobe set-ups. I tend to get lazy and just set-up my strobes to settings I’ve been used to using, and guess the power levels for my backlights and other sources. The better way is to use a flashmeter so that you can achieve accurate output levels the first time.
selecting a flashmeter:
There’s two flashmeters on the market which can wirelessly fire PocketWizard-equipped strobe set-ups:
The $379 Sekonic Litemaster Pro L-478DR is the top-of-the-line Sekonic flashmeter/incident meter, and is generally considered the best of the bunch. It has an attractive back-lit color LCD display, plus built-in wireless triggering capability, whereas the older (now discontinued) Sekonic L-358 requires purchasing an optional $74.95 Sekonic radio transmitter module, which is still currently still being sold and manufactured. Packed with features (including scales for cinematography), the L-478DR is a pleasure to use. An added feature (which not all meters display) is direct footcandle measurements. If you can possibly afford it, go for the L-478DR.
However, if the prices for the high-end Sekonics is a bit too steep, there’s a number of budget-priced flashmeters also available, but, you’ll have to fire your strobes manually, or use a sync cable to fire and meter your strobes. One import brand costs less than $50: Interfit flashmeter. The next step-up would be either a Polaris or lower-priced Sekonic. The Sekonic L-308S appears to be a good buy at $217. Other brands begin approaching the price of the Sekonic L-478DR, so you may as well save up a bit and try to buy the L-478DR if possible.
what does the meter reading mean?
Strictly speaking, your in-camera meter, handheld flash- or incident-meter, all read the same thing: 18% gray. The 18% gray value (represented in physical form by an 18% gray card) had long been a standard exposure target in photography, and represents the “middle tone” in the exposure range.
The “Zone System” is a method originated by Ansel Adams which prescribed a method of coordinated exposure and development for black and white negative film to optimize contrast range. In the Zone System, 18% gray represents “Zone V.” The Zone System breaks down a scene’s contrast range into 10 steps (i.e., Zones 1-10, often expressed in Roman numerals: I-X), with Zone 1 being the darkest, and Zone 10 being the lightest. For our purposes here, we’re only interested for the moment in Zone 6. Zone 6 is widely accepted to represent an “average” caucasian skin tone in a normally lit scene. So why does the meter show us Zone 5, if our typical exposure goal is one-stop higher, at Zone 6? Well, that’s just the way the system was established, and has become the de facto standard among photo equipment manufacturers for decades.
preserving highlight detail:
Regardless of the exposure method used, the primary goal in a typical exposure is two-fold: 1.) Maximize the dynamic range of the sensor or film stock; 2.) Preserve highlight detail. Since the advent of modern post-processing tools and RAW files, the tendency for some is to use automatic exposure and recover any lost highlights, or raise any detail-less shadow area in post. However, to make the best use of your camera’s sensor or your selected film emulsion, it’s best to “expose to the right” (known as “ETTR”). In a nutshell, ETTR simply means to make the greatest exposure without losing any detail in the highlights. Some have made the comparison of modern digital sensors to that of transparency film, where it’s generally the highlight detail which gets “lost” first, and therefore requires special attention to retain it. A 100% exposed sensor reads “256, 256, 256” for each of the RGB color channels, meaning there is no luminance information contained other than a value essentially equal to “0.”
In the image above, the exposure was raised slightly in post until the area circled in red began to lose detail:
Note that make-up can influence your acceptable exposure a great deal. If the subject’s skin is shiny due to perspiration or oily skin, your highlights will lose detail much faster than if an even, matte skin surface is photographed.