Putting it all together, correct exposure

Flying in a stunt plane with pilot Bill Carter.

Flying in a stunt plane with pilot Bill Carter.

In the past articles we have learned about the basic controls of the camera including setting the amount of time a recording surface is exposed to light entering in the camera through a hole in the lens of a predetermined size striking a recording surface that has various light sensitivities. Shutter speed, aperture and ISO are the basic camera control functions that you have to input (or let the camera do it for you) to create a properly exposed photograph, which the camera has a built in light meter for which will signal you when you have a proper combination of the three above. Consult your owners manual for your camera’s specific light meter as well as the location of all these controls.

Each of these controls, while having specific functions also create different effects. In order for you to be able to put everything together, there are some steps or questions you want to make sure you answer.

Woodcarver photo with aperture set at f/8 keeping carvings in focus and carver out of focus.

Woodcarver photo with aperture set at f/8 keeping carvings in focus and carver out of focus.

1. What is the subject? This is the most important question, you have to identify what it is you are going to photograph. This allows you to make proper decisions when your subject matter is clearly identified and you have a definite intention behind the photo. If you don’t know what you are interested in photographing, you certainly can’t choose options to show that subject.

2. What is the subject’s action? Is it a moving subject or a still subject? If a subject is sitting still, you may be able to shoot with a lower shutter speed whereas, if you want to freeze the action of a moving subject, then you want a higher shutter speed.

3. How much depth to the subject? This allows you to consider your depth of field. A scenic may see you choosing your aperture first, so, you make a decision on what sort of depth is to the subject and how much you want to show.

4. What are the light conditions the subject is in? This will help you determine the light sensitivity you set for your recording surface (or choose your film ISO). A nice sunlit day can have you work with 100 or 200 ISO while an overcast day may lead itself to 400 ISO. Inside an arena, school auditorium or school theater and you can’t use flash, you will probably be using 1600 ISO, and your fastest lens.

Lets review the standard shutter speed settings: “30” sec., 15” sec., 8” sec., 4” sec., 2” sec.,1” sec. (denoted by “), 1/2 sec., 1/4 sec, 1/8 sec, 1/15 sec., 1/30 sec., 1/60 sec., 1/125 sec. 1/250 sec., 1/500 sec., 1/1000 sec., 1/2000 sec., 1/4000 sec., 1/8000 sec” Standard Aperture settings: “f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22 and f/32” …and standard ASA settings: “100 ISO, 200 ISO, 400 ISO, 800 ISO, 1600 ISO, 3200 ISO and 6400 ISO.”

At attention in Fort Erie.

At attention in Fort Erie.

It’s a nice day out, bright, sunny. I have 100 ISO set on my camera. I want to take a photo of someone sitting, posed for a portrait. I take a meter reading and I get 1/60 sec. at f/8. I don’t have a tripod and I can’t brace and I am a little worried about camera shake. So I want to set a shutter speed of 1/125 sec. just to make sure that I freeze any movement produced when depressing the shutter. I changed the amount of time that the shutter is open by half, it’s open half as long, a difference of 1 stop meaning that I have to let twice as much light in through the lens to compensate, giving me an aperture of f/5.6, a difference of 1 stop.

Next, a little harder, it’s kind of cloudy out. I set 400 ISO for my sensitivity and I get a meter reading that says that my proper exposure is 1/2000 sec. at f/2.8. However, I am trying a scenic photo where I want my maximum depth of field. So I set my lens to f/22, a difference of 6 stops, f/2.8 to f/4 is one, f/4 to f/5.6 is two, f/5.6 to f/8 is three, f/8 to f/11 is four, f/11 to f/16 is five and f/16 to f/22 is six stops. When you make the hole in the lens smaller, you have to allow the shutter to remain open to compensate, in this example, by a number of 6 stops. The original shutter speed is 1/2000, so we have to hold it open longer by 6 stops. To 1/1000 sec. that would be one stop, 1/500 sec., two stops, 1/250 sec., three stops, 1/125th sec., four stops, 1/60 sec., five stops and 1/30 sec. six stops. That gives us 400 ISO, 1/30 sec. at f/22. Now, in remembering our rules, at 1/30 sec. we have to bring out a tripod, or find a solid surface to put the camera on, to take the photo because the shutter speed is too slow to handhold without producing a camera shake from the shutter release.

Calgary Flames hockey action at the Saddledome in 2000.

Calgary Flames hockey action at the Saddledome in 2000.

The next example is: we are in the hockey arena, a low light situation. We take a meter reading with our sensitivity set to 400 ISO and we get a reading of 1/125 sec. at f/2.8. It’s midget hockey and is fast action, so I want 1/500 sec. to freeze the action the best I can. I have a lens that will go to f/1.4. Can I get 1/500 sec. at f/1.4 with 400 ISO. Yes. The reason, the lens opening up to f/1.4 is an adjustment of two stops, from f/2.8 to f/2, then f/2 to f/1.4. We have to compensate for the more light coming in through the lens by reducing the amount of time the shutter is open by two stops, from 1/125 sec. to 1/250 sec., one stop, then from 1/250 sec. to 1/500 sec. is two stops. However, the lens is a 50mm lens and really doesn’t allow me to get close enough to the action, so I am going to use my 80-200mm f/2.8 lens with a widest maximum aperture of f/2.8. So, I take my original reading of 400 ISO, 1/125 sec. at f/2.8 and I want to work at 1/500 sec. Since I can’t open up my lens hole any more, I have to compensate using a different control. I have to change the sensitivity of my recording surface. Since I know that changing from 1/125 sec. to 1/500 sec. is an adjustment of two stops, I have to adjust my ISO rating by two stops making my recording surface more sensitive to light. So, we are at 400 ISO, change to 800 ISO, would be an adjustment of 1 stop letting us work at 1/250 sec. at f/2.8 as this is twice as sensitive to light as 400 ISO, but, we want 1600 ISO, an adjustment of two stops, which is twice as sensitive to light as 800 ISO and four times as sensitive to light as 400 ISO, to allow us to work at 1/500 sec. at f/2.8.

A swimmer underwater using aperture priority, f/16.

A swimmer underwater using aperture priority, f/16.

That’s pretty much it. Every time you move the shutter speed you have to adjust the aperture to compensate or vice versa. You change light sensitivity when you are in lower light to get the photo. Basically, I usually set my shutter speed first as I go to an event, then just choose the appropriate aperture that will give me a proper exposure according to the light sensitivity level of the recording surface I have set. If I want a lot of depth of field, in a scenic for example, I set the aperture first, which is generally around f/22 and set the appropriate shutter speed to give me a proper exposure as indicated by my camera’s built in light meter. A good chance I will be using a tripod for this as I expect to get into slower shutter speeds which make it impossible to handhold. It all starts with clearly identifying the subject matter and knowing what I want to accomplish or show in the photo.

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