P, S, A, M, Auto: what shooting mode to choose and 3 exercises to better understand why

Most reflex cameras (as well as hybrids) have 4 shooting modes represented by the letters P, S, A and M. What are these modes? What are they used for? How do you use them? Here are some tips that will hopefully give you a better understanding of how to use your camera.

P, S, A, M, Auto

Questions about shooting modes are among the most frequently asked by our novice readers. This is particularly true of those users who have grown accustomed to using compact or bridge cameras are who, as a result, are left completely in the dark when it comes to the apparent complexity of reflex cameras. Here is the essential information you should keep in mind regarding shooting modes.

The Auto mode is your friend (it really is!)

If you find yourself completely at a loss when confronted with your brand new reflex camera’s different shooting modes, fall back on the automatic mode!

While you might find this recommendation to be somewhat shocking given that this discussion is about reflex cameras and learning how to use their shooting modes, using the Auto mode is actually one of the best ways to start out in the development of your photography skills. Don’t concern yourself with the settings, try to take good photos. You should remember that the expensive camera you have just bought was conceived by engineers who have thoroughly considered the matter of providing the best settings for any given situation; rest assured, your camera will be able to deliver good results in the automatic mode.

The advantage of starting out this way is that you will be able to concentrate on your subject, on the light, on framing and composition without always attempting to use the best settings at the risk of missing a good photo opportunity.

P, S, A, M, Auto

Does it have a dial to choose shooting modes? It depends on the camera! The pictographs represent the Scene modes which we will not be covering in this article.

Only once you have acquired your camera and have become accustomed to using its essential functions will you be able to progress in your learning process by beginning to use the shooting modes described below.

Avoid at all costs using the manual mode as a fist step – contrary to what you may have heard elsewhere (from people trying to impress you) – since this mode is highly complex. It is entirely possible to take photos without using it. People who think otherwise are stuck in the 20th century.

P, S, A, M: I’m lost!

What mode should you fist start using after the automatic mode? Your reflex camera makes four modes available to you: P, S, A and M. Here is how each mode works.

Mode Shutter Speed Aperture
P (programmed auto) Selected by camera Selected by camera
S (shutter-priority auto) Selected by photographer Selected by camera
A (aperture-priority auto) Selected by camera Selected by photographer
M (manual) Selected by photographer Selected by photographer

P mode – Programmed Auto

Program mode is one in which the camera automatically chooses the aperture setting (diaphragm opening) as well as the shutter speed – in function of the amount of available light and the type of subject being framed.

P mode

On most cameras, all you need to do is to press the “Mode” button and then select the shooting mode by turning the wheel at the back of the device

Your reflex camera’s integrated algorithms are actually capable of telling whether the top part of the scene that you are framing contains a luminous sky, or, if you are in portrait mode, it will choose among tens of thousands of possible scene profiles contained in its memory banks to recognize the one which will provide the best exposure settings for your current situation. The results are visible on the histogram which can be viewed on the rear display.

P mode is probably the first mode you should try after the automatic mode. It is a mode which will begin to allow you to change some of the camera’s settings, to take more control over the camera and to start to make your own creative decisions.

Most of the time the P mode is adjustable: it is possible to turn your camera’s corresponding dial to shift the program. This means that you are able to modify the automatically chosen shutter speed / aperture settings in order to adapt them to your particular needs without modifying the actual amount of light entering the lens.

Imagine that you are trying to set your camera up to photograph an action scene before it happens (a child that is going to jump out in front of you for example); you have framed the scene and the camera has chosen shutter speed and aperture settings, but there is no way that it can know that the subject you intend to photograph will be moving. It is therefore up to you to shift the program by choosing a higher shutter speed in order to avoid a blurry image. In this way you are changing the pair of settings in order to produce the best possible exposure.

Don’t forget that in P mode, the camera always guarantees a correct exposure whether you have shifted the program or not. However, if you choose a shutter speed which is too high (or too low) and the corresponding aperture setting is unavailable, the camera will indicate the impossibility of releasing the shutter. In this case, you will need to modify the shutter speed setting.

Can you already see why the P mode is a more advanced mode than the automatic one? This mode provides you with automatically determined vales for both shutter speed and aperture and allows you to modify these values to suit your particular needs. You should fully explore this mode before moving on to anything more complicated!

A mode – Aperture-Priority Auto

A mode is probably the mode most commonly used by photographers. It is used to specify a fixed aperture value by using the diaphragm ring of a lens or a dial on the camera and to allow the camera to choose the appropriate shutter speed. By providing you with even more control than the P mode, the A mode will allow you to explore blurry background effects, to alter the depth of field and to influence the overall sharpness of the image.

A mode

In this example, in A mode, the camera indicates a speed/opening pair of 1/80°and f/7.1

What aperture should you choose? It all depends on your personal preference. All you need to do is to understand the notion of depth of field. Just remember that: the wider the opening, the less deep the depth of field will be. And vice versa.

A wide opening is characterized by a low diaphragm value (ex. f/4), while a narrow opening is characterized by a high diaphragm value (ex. f/16). In other words, the higher the number designating the opening, the deeper the depth of field. Do you follow?

Just remember that the A mode is the most creative mode since it allows you to isolate a subject from its background, to make a person stand out, to turn a landscape into a beautiful background, to play around with blurring, etc.

S mode – Shutter-Priority Auto

S mode is the opposite of A mode: it allows you to set a fixed value for the shutter speed and to let the camera calculate the requisite aperture.

S mode

In this example, in S mode, the camera indicates that there is not sufficient light to use the displayed speed of 1/500°

The bar graph indicates an under-exposure of 1/3 EV

The advantage of this mode if fairly obvious: if your subject is in motion (sports, action photography) you can choose your own shutter speed value in order to best prevent any blurring – the camera will take care of calculating the aperture value for you. In this way, any photos you take will be correctly exposed.

The S mode will lend a helping hand whenever you are faced with a rapidly moving subject and you need to follow its path of motion by taking a series of images (races, football matches, team sports, etc.).

Tip: If you only need to take a single photo, don’t bother using S mode, instead use P mode and shift the program to use a faster shutter speed.

If, on the other hand, you need to take a series of photos or if you intend to turn the camera off (to conserve battery life for example) during pauses, etc. you should use the S mode. This will avoid the need to shift the program every time that you turn the camera back on (who has never forgotten to do this?!); its always easier to concentrate on framing the scene without having to worry about the settings.

The S mode is not really very useful for taking photos when you are out for a stroll, while you are on vacation, on a trip… In these types of situations, you should use the A mode which gives you control over the depth of field. This will result in much more creative photos and you will still retain the ability to adjust the aperture setting to get a faster shutter speed value if the need arises. It only requires a slight adjustment.

M mode – Manual mode (the Holy Grail)

M mode is the mode which allows you to have total control over all of the shooting parameters and to adjust them to suit your needs. M mode allows you to do anything: whether good or bad.

M mode

In this example, in M mode, the camera indicates that the chosen settings are totally incompatible with the available light – almost 3 EV units of over-exposure.

The M mode allows for all possible value variants (and the exposure errors that go with them). Some heretics who are still living in the 20th century consider that any real photographer should use the M mode (photographers who don’t use it are not real ones?), however it is far from being widely used by everyone, including professional photographers.

If you decide to use the M mode, you must realize that you will be the only one in control of the camera. The camera will cease to do anything automatically and will not supply you with any preset values – you will need to set both the shutter speed and the aperture yourself. This mode requires that you have a perfect understanding of photography techniques, of light measurement and management as well as full knowledge of the abilities of your photographic equipment. We recommend that novice users do not attempt to use this mode since they run the risk of quickly becoming discouraged by the poorly exposed photos that they will undoubtedly take.

Digital reflex cameras will in some measure come to your rescue if you do decide to use the M mode. They will provide you with useful information; the shutter speed and aperture values that the camera would have automatically chosen are indicated on the viewfinder or the display. These indications can often be extremely useful and most photographers base their own manual settings on these automatically selected ones.

Imagine that a subject is in a situation of high contrast with a very dark foreground and a very light background. The camera’s automatic functions will propose an exposure setting (via the bar graphs on the viewfinder most of the time) which offers an acceptable rendition of both the bright and dark portions of the image. These proposed settings are often the correct ones but are equally often disappointing in terms of creativity.

With the M mode, you will be able to base your decision on the data provided by the camera without necessarily choosing to use the suggested settings. You will be able to choose a wide aperture in low-light situations or a narrower opening when the light is very intense. You’re in control! It’s up to you know what kind of effect you would like to obtain and to make any necessary adjustments to the settings.

Nothing beats practice for developing your skills!

Take a moment to find a scene you would like to photograph. Follow the few simple steps below to leave the Auto mode behind and begin to understand how to select your own camera settings.

Exercise: going from P mode to A mode

  1. set your camera to use P mode
  2. frame the scene and take note of the suggested shutter speed and aperture settings
  3. shift the program and observe the changes made to the proposed shutter speed and aperture settings
  4. set your camera to use A mode
  5. choose the aperture setting which was suggested to you by the camera in P mode (step 1)
  6. take a first photo
  7. have some fun, shift the aperture value to see how the shutter speed changes; take a few photos every time you change the aperture.

You will be able to observe the different results in function of the different aperture. The wider the aperture, the blurrier the background will be – if you were focusing on a subject in the foreground of the scene.

Exercise: going from P mode to S mode

  1. set your camera to use the S mode and select an average shutter speed (1/250°for instance)
  2. take a photo using the aperture suggested by the camera
  3. have fun changing the shutter speed and observe how the aperture value also changes
  4. take a photo at each different speed and compare the results obtained by using each of the different values.

You will see that setting the shutter speed allows you to freeze the subject or to make it blurry. However, the sharpness of the background also changes since the depth of field is not the same for each image. Are you starting to understand?

Exercise: going from P mode to M mode

Have you tried playing around with the A and S modes? Try the M mode!

  1. Set your camera to use the P mode and take note of the proposed shutter speed and aperture values
  2. Switch to M mode and choose the values proposed to you in step 1, your exposure settings will be correct
  3. take a photo for reference purposes
  4. have fun varying the shutter speed and aperture settings and observe the different effects produced

We recommend that you only vary one of the two settings at a time or else you run the risk of quickly becoming confused. Observe the changes which took place relative to the reference image: in terms of depth of field, contrast, exposure of the dark and light zones, blurriness, etc.

With a little bit of practice, you will soon become accustomed to using the A and S modes in order to take full advantage of your camera’s abilities and to give free rein to your creativity. With just a little bit more practice, you will master the M mode and all of the freedom it can offer. And, if at any point you are feeling confused, don’t forget our first piece of advice: fall back on the Auto (or the P mode) and just take some pictures!

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