Basics of Manual Exposure

Want to know the secret between a ho-hum, average image, and a stop you you in your tracks, beautiful image? Well, truth be told, there’s no one real secret, but a great way to set your images apart is to shoot in manual exposure mode. Once you start shooting in manual mode, you take control of your image from idea to execution, and you don’t have to rely as heavily on post processing to “fix” your image. When your base image is perfectly exposed, editing becomes easier, and a way of refining or finessing your vision, rather than trying to undo what the camera thought was the proper exposure.

When we talk about shooting in manual mode, there are four main things to consider: middle gray, shutter speed, aperture, and ISO. The way these four points act together tells us what we should choose for our settings.

Let’s start with middle gray. When you look through a camera viewfinder, you will find a scale, typically at the bottom, but sometimes on the side that looks something like this:

-…|…|…0…|…|…+

Depending on your camera make and model, the +/- might be reversed, and if that’s the case, then just move the dials accordingly the direction you need to go. Middle gray is the 0 in the graph. Your camera’s goal, when shooting in auto-exposure, is to balance the scene in front of you so that there are not really bright areas or really dark areas, and to average it all out to a middle gray tone. Depending on the scene, you might still end up with really bright areas and/or really dark areas, but in general, the camera wants to balance these out. In some cases, this is a fine choice and your image will still come out as you intended when shooting in auto mode. However, most scenes aren’t enhanced by an exposure of middle gray. Think about shooting a photo of a white swan; do you want the swan to be gray or white? Of course you would want it to be white; in manual mode, you can tell your camera to override the settings it suggests and ensure that the swan turns out white.

Shutter speed is how long the shutter on your camera is open. A slow shutter speed lets in a lot of light and a fast shutter speed lets in a little bit of light. Typically shutter speed is measured in a fraction of a second, like 1/125, or 1/4000. How long the shutter is open depends on your creative vision, the amount of available light, and how your aperture and ISO are set.

Aperture is how much light gets in through the lens of your camera. Much like your pupils dilate in dim light and get larger, when you have a large aperture setting for your lens, you are letting a lot of light in. However, aperture is also used for creative effects; when you see an image with a “blurry background” that is mostly the due to the aperture being wide or near wide open. A wide aperture would be something like f/1.4 or f/2, for instance; if you are not shooting wide open, the the lens is considered to be stopped down, which means that the aperture is getting smaller. Not only does a smaller aperture let in less light, but you will also get a larger portion of your image in focus. Stopping down your lens is great for when you have either a very bright day and you need to ensure you don’t get too much light to the sensor, or because you are shooting a group of people or something that you want to ensure is in focus completely from front to back.

The last piece to consider is ISO. This is an electronic setting that mimics the old ASA/ISO ratings of film. The lower the ISO, the less light gets to the sensor, but also the less noise your image will have. The higher the ISO, the more light gets to the sensor, but often this creates undesirable noise in your image, particularly in the shadows. Luckily modern cameras have much lower noise than even ones from a few years ago, and raising ISO should not be a concern.

So, now that you know what the four factors are, how do you make them work together? For my style of shooting, I typically choose the aperture first. I generally like a very shallow depth of field, which means that only a small part of my image is in sharp focus. Of course, if I am shooting a landscape or a photo of my kids and their friends, I will certainly stop down for a larger area of focus throughout the photo. But determining how deep that focus needs to be in any given image is my first priority.

After I decide my aperture, I think about what kind of shutter speed I need. Is it windy? That will require a fast shutter speed to help freeze motion. Am I working on a tripod with a stationary subject? Then I can use a slower shutter speed. If I am handholding a camera outside I will typically try to use a minimum shutter speed of 1/250 or so. There are always caveats to what minimum you can use. Experienced shooters who are very steady may be able to handhold a much slower speeds, and newer gear steps with IBIS (in body image stabilization) may also be able to use a slower shutter speed. However, as you practice, I encourage you to keep a slightly higher shutter speed to ensure your image is in focus. As you gain more experience you can begin to see how slow your shutter can be while shooting.

The last thing I set is my ISO. This is because other than possibly determining how much noise you introduce to an image, ISO has no creative affect on your photo. It is mainly used as a lever between the other two parameters to acheive the right exposure overall.

Now that you have a preliminary understanding of the four main concepts, how do you make them work for you? Remember above when I said that we were shooting a white swan and wanted to ensure it was white? I would first choose my aperture. I would probably choose something like f/4 to separate the swan a bit from his background, but to also have make sure he is in focus the whole way. Then I would choose my shutter speed. If he is still, I would use my target SS of 1/250, but if he is swimming in a pond, then I would choose something faster like 1/800 to ensure that there isn’t any motion blur from his movement. Lastly I would set my ISO. If you were setting the ISO to match the auto exposure of your camera, you would choose whatever ISO gets you to -0- on your camera meter. However, keep in mind, that auto exposure wants to make -0- middle gray, so your white swan will then come out also middle gray toned. But we don’t want a gray swan! We want a white swan! In this case we would get set the ISO so that the reading is actually at +1 on the meter (each hash above is one stop, and each . is 1/3 of a stop). This tells our camera we want to overexpose this image by one stop to make sure our white swan stays white.

Similarly, if you are shooting something darker toned, like my dog Halley, you will want to set your camera for a bit of underexposure. Again, because the camera wants to make the main subject middle gray, the black dog will become gray if left to the camera to make the decision. I typically meter her about one stop under -0-.

With newer mirrorless camera that have an EVF (electronic viewfinder), working in manual mode is easier than ever since you can see the effects of your setting in the preview before you even take the photo. However, I still like to practice metering without the EVF as I also shoot a lot of film. Metering is slightly different in film, but much more important since there is not nearly as much latitude in post processing with film; although you can tweak contrast and colors a bit, if you substantially over or underexpose with film, you will lose your image.

All the images in the post are film images and having the solid foundation of metering under my belt really helped me transition seemlessly into shooting film.

As a bonus to my readers, I am including a 20-page ebook which goes even more in depth to manual exposure, metering, and how to use your settings creatively. I hope this helps you further understand the concepts outlined in this post, and as always, feel free to leave a comment below or send me an email with any more questions!