For most people starting out in film photography, particularly black and white film photography, properly exposing a negative seems like a dauntless task. There are all these crazy words that don’t make sense being tossed around. And then they try to confuse you by talking about zone system, over exposing and underexposing and what the hell is “Stop” anyway? Well I’m here to help break it down for you in plain old English in layman’s terms.
How a light meter works. Up until fairly recently all in camera light meters measured light the same way for all films. Towards the end of the film camera era technology got more advanced and they came up with new ways to meter but the majority of cameras were calibrated to find “middle gray” which is somewhere around 18 percent reflected light depending on the manufacturer. If you had a grey card you could calibrate your camera settings to middle gray and theoretically get consistent results.
But I don’t have a light meter!
A lot of times you may have a classic manual camera that takes a hard to find or illegal Mercury battery or perhaps it’s a camera that functions fine with the exception of the light meter. A working built in light meter has been standard in most cameras for so long that many people think it’s essential to photography, but I’m here to tell you it’s not. You don’t need a light meter in your camera or even in your camera bag. I’m not telling you to throw one away or to tell you that if you shouldn’t buy one. I’m just saying that if the lack of a light meter is the only thing stopping you from getting out and shooting there is a solution that works great and is free.
A light meter is a nice luxury to have but being able to shoot without one is a good skill to have as well. I was on the other side of the world very far from home and I had a vintage handheld meter that died when a drunk at a bar dropped it on the patio. Without my cheat sheet from Fred Parker’s website I wouldn’t have been able to use most of the cameras I brought with me since most of them either didn’t have a meter or the meter didn’t work. But by knowing a few basic rules and common anchoring points for certain lighting situations I was able to get great photos without one.
Fred Parker’s website is well-known among photographers that spend time online. It is called the ultimate exposure calculator. http://www.fredparker.com/ultexp1.htm It’s not overly technical, but for someone just starting out on film photography it might not all make sense. There are a couple of basics you need to know and understand for all the pieces to fit together. The rest of this article is a good primer for using the ultimate exposure calculator.
Film Speed. Film speed is a way of measuring the speed in which your film reacts to light. The faster the film (the higher the ISO) the less time is required to make an exposure. What gets confusing is that the actual box speed on any given film may be lower the advertised. There are some simple but time-consuming tests you can do to find your actual film speed. How you process your film and how you meter (or not meter) have an effect on your negatives. If you care about this kind of stuff I can’t recommend Ansel Adam’s book The Negative enough. However if you just want the nuts and bolts of manual photography read on.
Aperture. The hardest part for a new photography to wrap their mind around is that the smaller the number, the more light a lens lets in. This is commonly known as an F stop. This concept baffles people because they assume a small number means a small hole. F22 sounds way bigger then F1, right? And then they go and call it a stop. Now everyone is really confused. Why do they make it this hard? Well hang in there tiger! They call it a stop because on many lenses made before plastic was invented there was an actual “click” between settings and so it became common in photography vernacular to refer to the distance between clicks as stops. Some lenses have half stops in between the numbers. Cameras that control aperture digitally may even have 1/3 stops. The common settings let in exactly twice as much light as the previous setting. When you get at the bottom of the scale the stops may not be in whole increments as an example F1.7 is a little more than one stop below F2.8. One stop below f2.8 is F2 but F1.8 and F1.7 let in a little more light and look more impressive for marketing. Don’t get too hung up on the numbers eventually they’ll either come to you or you can ignore them and go happily on your way.
Shutter Speed. These are measured as fractions of a second. 500 is 1/500th of a second. Beware: Old Cameras lie. Your camera may not be exactly spot on. Luckily film is forgiving stuff. As in aperture each stop lets in twice as much (or half as much) light. So 1000 is twice as fast as 500 so that’s one stop. 250 is 2 times as slow as 1000 so that’s two stops and so on.
All things being equal if you let in less light through the aperture you must keep the shutter open longer to achieve the same exposure. If you let in more light you must reduce the amount of time the shutter stays open. Shutter speed has an effect of motion. The longer a shutter is open the more movement and camera shake is recorded. Aperture affects Depth of Field, the sharpness and contrast of your lens. In the useful range of things the larger the aperture the softer the image and contrast. This is why top performing high-end lenses tend to cost more to make and cost more for you to buy.
Without getting super scientific I will mention that for really long exposures the law that we work with within normal parameters does not fully apply. This is due to reciprocity law failure or Schwarzschild effect. If you have questions or that applies to you than you can Google it.
Exposure Value or EV. Exposure Value or EV makes it easier for some to visualize the amount of light available based on conditions. Please refer to Fred Parker’s website, he’ll even let you download and print his very useful scale for your personal use. I use it frequently and it’s never let me down. The relationship between your film speed, aperture and shutter speed result in an EV. Some cameras actually had an EV scale built-in. My Minolta 7s has this feature and it’s really useful. Once you get the hang of it it becomes intuitive.
The Sunny 16 rule. The sunny 16 rule works great. Some film manufactures even print it on the inside of their boxed film. The principle is that if your shutter speed is set to the nearest setting equal to speed of the film (i.e. 500 for 400 ISO, 200 for 200 ISO etc) in bright full sun conditions you’ll use f16 for normal exposure. And if it’s not sunny? Well if it’s cloudy but still bright you could either decrease your shutter speed down one stop or maintain your shutter speed and open up your aperture one stop. As an example 500 at F11 is equal to 1000 at f8. Both of these result in an EV one stop lower then 500 at f16. Fred Parkers website has a chart which gives you common lighting conditions and their EV to use as a guide. It’s amazing how well the method actually works once you get the hang of it.