An exposure to exposure meters

Throughout my articles on the basics of photography, I've emphasized getting the correct exposure. I've given you mathematical formulas and various theories for achieving the ever-elusive perfect exposure. During some of these articles, you may recall me mentioning the use of exposure meters. In this piece, I'll finally be acquainting you with this indispensable little gadget.

What it's for

What does an exposure meter do? It gives you the correct exposure for any photographic situation you'll encounter. By measuring either the light reflecting off of, or falling on the subject, the exposure meter will calculate the perfect aperture (f-stop) and/or shutter speed for every shot. Using the exposure from your meter, your shots will have perfect depth of field every time.

Different types of exposure meters

Exposure meters come in several different varieties, and can be used a couple of different ways. Light meters are designed to measure ambient light only, flash meters are used in flash photography, and combination meters perform the functions of both light and flash meters.

The simplest exposure meter is the one built into the camera. These TTL (through the lens) meters measure the reflected light coming off of the subject. Some of them are center-weighted, measuring the center section of the frame, and some use intelligent metering, measuring multiple areas of the frame and computing for what it thinks is the best exposure.

These meters typically convey the measurement in the form of a balance scale visible inside the viewfinder, with (+) pluses indicating overexposed, and (-) minuses underexposed. The goal with these is to adjust your shutter speed and aperture, even the amount of light if possible, in order to get the exposure reading of the meter in the center for a basically-correct exposure. You may actually want to expose with the reading a mark or so on the over side.

Unless you're using a flash device that's specifically designed to work with the TTL metering of your camera, these meters will not work in flash photography, you'll need a flash meter for that.

While these reflected-light TTL meters will get you in the ballpark, they aren't going to put the ball over the plate. You need something a little more sophisticated to get the "perfect" exposure. For this, we need to move away from the camera to a dedicated gadget.

A light meter is a handheld exposure meter for reading the exposure of ambient lighting, or non-flash photography. Although it's a rather old model, an example of a light meter can be found in Figure A.

Even though this is an older model light meter, it still functions great. That's the nice thing about photography; the rules don't change with time, only the sophistication of the equipment. Unlike things in other sectors, as long the equipment is well cared for and maintained, it doesn't matter how old your photography equipment is, it'll still return excellent results. I have a camera that's more than twice as old as I am, and the pictures it takes are every bit as good as the first roll it shot. Another advantage -- you can often pick up used equipment off eBay or your local swap meet for very little cash.

All of the meters, regardless of whether they're light, flash, or combo meters, work pretty much the same way. You set the speed, or ISO/ASA, of the film you're using, measure the light, either reflected or incidental, then use the measured reading to compute your exposure.

In the case of the light meter in Figure A, you set the film speed by turning the center dial until the arrow points at the speed of the film being shot. When you measure the light index, the needle in the bottom window of the meter will advance. By turning the outer dial of the meter to match the number the needle is pointing at, you'll be given the correct shutter speed for the aperture you're using, or vice versa. This particular meter can also be used when shooting movie film, as seen in the Cine window.

The meter in Figure B is a flash meter, although a rather rudimentary one, but it still gets the job done.

Like with the light meter in Figure A, you set the flash meter with the speed of the film you're shooting. On the side of the flash meter is a PC connection to plug your flash unit into, and the little lightning bolt corresponds to the button for firing the flash. By the way, this PC connection is used in older cameras, not for connection to your computer. You measure the flash by placing the meter next to the subject and firing the flash. One of the red LEDs at the top will light up; you then turn the dial until the small orange arrow points to the same number. The large orange arrow at the bottom will now points to the correct exposure.

In some cases, the meter may be calibrated for a specific shutter speed, such as 1/125th. If your camera syncs at a different speed, you may have to adjust the setting. In the case of this meter, the owner's manual includes an adjustment chart.

With both of these meters, the small white dome can be moved to directly expose the photocell for reading the light reflecting off the subject, but is slid over to cover the cell when measuring incident light. The cell is exposed for reflective measurements because the intensity of the recorded light is less than if reading the total incidental light falling on the subject.

Combination meters, like the Sekonic L558R DualMaster in Figure C, give you the best of both worlds, combining a light meter and a flash meter for all your exposure needs.

Where to use

Exposure meters can be used in virtually any photographic setting where you want to ensure you get the perfect exposure. Ideally, they're suited to studio-type work, but they can be used outdoors, and even in action shots. How can you use an exposure meter in an action shot? It's quite simple actually.

The secret to using an exposure meter on an action shot, and getting that perfect exposure, is to have your shot pre-planned. Let's take for example, a snowboarder getting air off a mogul. You would be in your pre-planned spot, waiting for your subject to come down the hill and grab some air.

Since everything about this shot is controlled up to the moment you're ready to trigger the shutter, you can use a stand-in for your target and take the reading from this stationary substitute. With the appropriate reading, you can now set your shutter speed and aperture to get the perfect shot when that snowboarder comes down the hill and sails over your head. This same technique can be used in any number of situations where you want to make sure you get the right exposure, but only have one shot at getting it right.

An exposure meter is an indispensable tool for any photographer who wants to get every shot right, every time. Which type of meter you get depends primarily on the type of photographs you take. If available-light photography is your preference, then a flash meter won't do you much good. And if you shoot a lot of flash photography, a standard light meter won't fit the bill. If you sample a little bit of both in your routine photography, then a combo meter is clearly the way to go. In either case, a good exposure meter will ensure you get the proper exposure for every shot. Good luck and good shooting.