For the purpose of this photography tutorial on exposure control in all shooting modes, let’s assume that you’re not using auto ISO. So, once you set your ISO, it stays at that setting and won’t change with the changing conditions.
Now let’s look at the exposure control decisions you need to make in each shooting mode. These are things to take into consideration when setting your camera’s shooting mode.
What shooting modes are there?
- Program mode
- Aperture priority mode
- Shutter priority mode
- Manual mode
I haven’t included auto mode in this tutorial, as it’s the least useful shooting mode to use for a DSLR. Program mode is similar to auto mode, but better, so it would be much better to use this. Also not included are the scene modes as these are also automatic settings for exposure control.
Further reading: What are the best shooting modes to use and why?
To understand when and how to use each shooting mode, we must first understand:
- The advantages of each shooting mode
- Exposure metering for program mode, aperture priority and shutter priority modes
For more information on controlling exposure, check out the previous 3 tutorials in this series on understanding exposure:
1. The advantages of each shooting mode
To fully appreciate the advantages of each shooting mode and exposure control in all shooting modes, we need to compare the four shooting modes.
Aperture priority is the next most popular shooting mode after program mode for beginners, so we’ll use this as the basis of comparison.
Aperture priority (A or AV) vs Program mode
Although with both shooting modes the camera makes the final decision on controlling the exposure, in aperture priority mode you have greater creative input.
The camera decides on both the aperture and the shutter speed. It chooses the best handheld option for the lighting conditions, so ensures that the shutter speed isn’t too low.
Aperture priority mode
You have control of the aperture setting and the camera automatically sets the appropriate shutter speed for the lighting conditions. This gives you creative control over the depth of field of your image, whilst most of the time (I’ll get back to this in a moment) ensuring a correctly exposed image.
It doesn’t, however, consider if you’re handholding your camera or not when setting the shutter speed.
Why use aperture priority mode?
Depth of field – either narrow for a blurry background, or deep for front to back sharpness.
So, it’s up to you to decide on whether you want a blurry background (large aperture/small f number) or front to back sharpness (small aperture/large f number), and the camera will adjust the shutter speed accordingly.
Which leads me to the next comparison…
Aperture priority vs Shutter priority (S or TV)
Because in aperture priority mode, the camera doesn’t take into account whether you’re handholding the camera or have it fixed to a tripod, you need to keep an eye on the shutter speed to make sure that it doesn’t drop too low.
Shutter priority mode
You’re in control of the shutter speed.
The camera is not concerned about the maximum f-stop of your lens. So, if you’re not aware of what’s happening with the change in aperture, you could end up with an incorrect exposure. The camera can only go to the maximum (or minimum) f-stop of your lens and if you select a shutter speed beyond this, it will over or under expose your photo.
Why use shutter priority mode?
To freeze the action with a fast shutter speed, or show movement with a slow shutter speed, or use a slow shutter speed for a long exposure to capture a very dark scene.
Aperture priority vs Manual mode (M)
Ease of use and the ability to get the shot done quickly, with the correct exposure, is the advantage of using aperture priority over manual mode.
In a fast moving situation, such as the confetti toss at a wedding (see photo at the start of this tutorial), where you don’t have the time to keep an eye on the exposure indicator, as well as adjust the aperture or shutter speed accordingly, aperture priority mode is helpful. Especially if you’re not 100% comfortable working in manual mode.
It beats everything for putting you in creative control of your camera and the end result of the shot.
You may wish to slow down the shutter speed or widen the depth of field from one shot to the next to get variety from the scene in the shortest amount of time. If you’re shooting in manual mode, this is easily done.
Why use manual mode?
Creativity and complete control over your camera and the outcome of your image.
2. Exposure metering for program, aperture priority and shutter priority modes
You leave the final decision on the exposure to your camera when using:
- Program mode
- Aperture priority mode
- Shutter priority mode
Unless you know how to control exposure in all shooting modes.
In manual mode you make the final decision on exposure, but you still need to be aware of how your camera’s exposure meter can be confused so that you can accurately adjust the exposure.
What confuses the exposure meter?
Let’s take the example of a black cat on a white couch vs white cat on a black couch.
Both scenes are black and white, but one has a large bright area (white couch) and the other has a large dark area (black couch). If you had exactly the same light in each scenario, your camera would meter it differently.
The white couch reflects more light than the black couch and your camera’s inbuilt exposure meter measures reflected light. As it wants to make everything an average grey, it will under expose the white couch scene and over expose the black couch scene.
Here’s another factor to consider – composition
What if you get in close and fill the frame with the cat’s face? No couch included.
A white cat photographed on a white couch is going to be the same exposure reading as a white cat photographed on a black couch (ignoring for the sake of simplicity, the negative fill caused by the black couch).
Let’s compare exposure control for these two photos
Our two models have similar colouring and are both wearing dark clothes. In each scenario the models are in the shade and shot with natural light. The only difference is the background – one is light and the other is dark.
I used manual mode with spot metering and metered the exposure off the models’ faces. The aperture for both shots is f2.8.
- If matrix metering had been used, the bright background would have influenced the exposure reading.
- Center weighted metering would have caused an inaccurate exposure, because of the dominance of her dark coat and hair.
- A wide aperture was used to blur the background and so separate the subject from the background.
- If I’d used aperture priority mode, to create a blurred background, I would have increased the exposure compensation to counteract the camera’s exposure meter wanting to under expose the image
- With matrix metering the dark wall and her clothes would have dominated the exposure metering and the model would have been over exposed.
- However, I could have used negative exposure compensation to counteract the camera’s desire to over expose the image.
- Partial or center weighted metering would have metered the centre of the image, mainly the background, and not the model.
- If I’d used aperture priority, I could also have decreased exposure compensation.
Exposure metering modes
As I said, you’ll need to decide how much of the scene you’re going to photograph, so you know much of the scene to meter. In other words, which metering mode to use? We discussed exposure metering modes in part 2 of this series, so I’ll just mention them briefly:
Matrix metering measures the exposure of the entire scene.
Partial metering (Canon only) meters 8 – 13% of the center of the scene.
Center weighted metering measures about 60% of the center of the scene, regardless of where you’re focusing.
Spot metering meters the area around your single focus point, which you’ve selected. This is about 2 – 4% of the scene.
Shot with natural light, in program mode, using center-weighted metering. The camera exposed for the central part of the image, the table and top of the chairs framing the central composition. The floor was allowed to underexpose, highlighting the main subject, the table setting.
Camera settings: 1/50th at f3.5.
Controlling exposure in all shooting modes
Now that you’ve decided on the best metering mode for the situation, you can decide if you need to use exposure compensation to overcome your camera’s limitations using any shooting mode. Just remember that you won’t see the exposure indicator until setting your exposure compensation and moving it from 0, either positively for a brighter exposure or negatively for a darker exposure.
Knowing how to control exposure in all shooting modes puts you in creative control of the final exposure.Just because you’re not shooting in manual mode, it doesn’t mean you can’t get creative with your exposures.Click To Tweet
The first three in the series on understanding exposure…
Next up – part 5 – pros, cons and how to use auto ISO
Sometimes there’s so much going on that you need a little help. Next, we look at the benefits and limitations of using auto ISO – even in manual mode!
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By Jane Allan
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