The backward thinking of manual exposure

Learning how to make a manual exposure is an essential step if you want to really learn how to get the most out a DSLR camera. However, it’s a step that most people get tripped up on. The concepts takes some practice to understand but mostly it’s the terminology that really confuses people.

(8/30/18) San Joaquin Delta College student Beny Dawson looks through his school-issued film cameras while participating in a lesson of the Photo 1A beginning black/and white photography class on the Delta campus in Stockton. [CLIFFORD OTO/THE STOCKTON RECORD]

There are three major factors in making an exposure, often known as the “exposure triangle.” The first is ISO. It controls the light sensitivity of your camera. This is pretty straightforward. The higher the sensitivity, the lower light you’ll be able to take photos in. There’s a tradeoff, though. The higher the sensitivity, the more noise, those little colored specks you often see in low-light photos, that you’ll get in your images. The scale used here is pretty logical. The lower numbers represent low sensitivity, the higher numbers correspond to more sensitivity. Fortunately, one usually just sets the ISO for the situation and forgets about it unless the lighting situation changes dramatically.

Difficulties start to appear when you talk about shutter speed and aperture.

(8/30/18) San Joaquin Delta College students Lisa Sovuth, left, and Stefanie Palacio looks through their school-issued film cameras while participating in a lesson of the Photo 1A beginning black/and white photography class on the Delta campus in Stockton. [CLIFFORD OTO/THE STOCKTON RECORD]

The two work together to allow a certain amount of light through to your camera’s sensor. Think of a garden hose. Aperture is the diameter of the hose. A hose with a large opening will let out more water than one with a smaller opening. A shutter speed is the velocity at which the water comes out of the hose. More water will come out the faster the water is flowing. This is easy enough to understand but the learning the numbers requires a little backwards thinking.

LEFT: (6/16/10) Jockey Diana Skinner rides mule Jessica Nelson in the first race at the San Joaquin County Fair. A fast shutter speed of 1/500th of a second freezes the motion of the horses and jockeys. RIGHT: (6/16/10) Genaro Vallejo jockeys Wild Wes to a win in the third race at the San Joaquin County Fair. A slower shutter speed of 1/125th of a second caused the background and the horse’s legs to blur. The rest of the horse an jockey are sharp because the camera and lens were panned with the motion. [CLIFFORD OTO/THE STOCKTON RECORD]

Shutter speed numbers represents the time, from full seconds to fractions thereof, that light is exposed to the camera’s sensor. While long timed-exposures and may last for many seconds or even minutes, most exposures consist of bite-sized portions. Most will be something like 1/60th, 1/125th or 1/250th of a second, etc. To save space on a camera’s information panel, they are usually represented by the just bottom number: 60, 125, 250. The problem here is that the larger numbers represent the smaller fraction of time and vice versa. If you keep in mind that they’re fractions of seconds, then it’s a little easier to understand.

LEFT: (7/21/10) Light shines through the aperture blades of a Nikon 17-35mm zoom lens. RIGHT: (8/20/18) The aperture scale on a 24mm Canon lens mounted on a Canon F-1 camera. [CLIFFORD OTO/THE STOCKTON RECORD]

The aperture scale represents the aperture opening of the lens and can be even more confusing. It’s segmented into what are called “f/stops” or simply “stops.” The scale starts at its widest opening, which lets in the most amount of light to the smallest opening which lets in the least light. Each full stop either doubles or halves the amount of light of the next stop depending on whether it comes before or after that stop. For example, stop “B” is twice as much light as stop “A” that comes before it, but only half as much as stop “C” which comes after it. All this takes some time and practice to get used to, but wait, it gets worse.

LEFT: (6/6/11) Golden poppies grow at the Stockton Sailing Club beneath cloudy skies at Buckley Cove in Stockton. A single poppy is in focus due to a wide aperture of f/3.2. RIGHT: More poppies are in focus due to a small aperture of f/16. [CLIFFORD OTO/THE STOCKTON RECORD]

Each stop is represented by what’s called an “f/“ number. However, the smallest numbers represent the largest openings, while the larger numbers correspond to the smaller apertures. So, an aperture of f/11 is much smaller than f/4 even though, counterintuitively, the numbers suggest otherwise. Also, even though each aperture stop doubles or halves, the actual f/number doubles or halves every other stop.

LEFT: (8/5/15) Spools of colored yard on a hat embroidering machine at the Dorfman Pacific Hats in Stockton. A single spool is in focus due to a wide aperture of f/2.8. RIGHT: More spools are in focus due to a smaller aperture of f/8. [CLIFFORD OTO/THE STOCKTON RECORD]

So why bother with all this in the first place when automatic modes can do an adequate job? Auto exposures will measure the overall average amount of light in a scene without much precision. Manual exposures allow you to have total control. Do you want a lot of depth of field (the amount in focus) or just a sliver of tack sharpness while the rest of the image blurs out? Do you want to freeze the movement of a fast moving person or object, or do you want to allow some motion blur to give your images some energy? These questions are things that the camera can’t decide for you, it’s up to you. So, you may have to endure a little backward thinking, but learning manual exposure will put you in the photographic driver’s seat

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