Using P, A, S and M Modes

Using Program AE, Shutter Priority, Aperture Priority and Manual Modes

Modern SLR cameras (both film and digital) as well as prosumer cameras (those dSLR wannabes) and some of the more advanced compact digital cameras have on their mode dials P, A, S and M (or P, Av, TV and M on some cameras, such as Canons). These modes allow you to control the finest aspects of the camera’s exposure, allowing you to create the same effects as the built in modes such as portrait mode and landscape mode, but with a much greater degree of control. In this tutorial, I’ll explain how the P, A, S and M modes work, and how to use them to get the same effects that you get in the pre-programmed modes, and how to use them to fine tune the effects.

Please note that these modes don’t adjust the ISO of your camera, so ISO won’t be mentioned very much in this tutorial.


Overviews of P, A, S and M Modes

First, an over view of how each mode works. In this tutorial, I’m assuming that you’ve read my tutorial on shutter speed, aperture and ISO which you can find here: [link]

Program AE Mode
This mode (Labelled P on the camera’s mode dial) is almost fully automatic; however, it does allow you to control some aspects of the camera’s operation (such as the flash). In this mode, the camera examines the light levels of the scene and uses the metering pattern you have set to determine a combination of aperture and shutter speed. However, if you’ve read the shutter speed, aperture and ISO tutorial, you’ll know that there are several different combinations of shutter speed and aperture and ISO that will give you the same exposure. Program AE allows you to change the exposure settings – it will give you different combinations of shutter speed and aperture while maintaining the same exposure. To change this, you simply have to turn the camera’s main dial (the one that you use to adjust shutter speed and aperture; see your camera’s manual for more information). So, if the camera decides that a shutter speed of 1/250 seconds at f8 will give the correct exposure, you can turn the main dial and the camera will change the exposure to 1/500 seconds at f5.6. If you turn it the other way, it will give you 1/125 seconds at f11. Each of these allows in the same amount of light, but it allows you to have some control over how much movement is shown (controlled by shutter speed), and the depth of field (controlled by aperture).

This mode is good if you’re expecting a photo to appear at any moment. All you have to do is pick up your camera, aim and shoot. The camera makes all the decisions. There’s the old rule of photography – “It doesn’t matter what mode your camera is in, as long as you get the shot” – although this mode doesn’t really give you as much creative control as the other modes.

Aperture Priority Mode
In this mode (labelled either A or Av), you’re able to set the aperture of the lens manually, and the camera will automatically set the shutter speed to give what the camera thinks is a correct exposure. When in Aperture mode, you have direct control over depth of field.

You also have indirect control over the shutter speed, because as you open up the aperture, the camera has to give a shorter shutter speed to compensate for the extra light coming in. However, you can never have precise control over shutter speed in this mode, because the camera is constantly adjusting the shutter speed to keep the aperture you have set. So, if you set an aperture of f5.6, the camera is constantly adjusting the shutter speed to give a correct exposure without altering that aperture.

This mode is good if you want to have primary control over the depth of field, such as when you are taking portrait photos or if you are taking landscapes. I’ll expand more on how depth of field is important in these two situations later.

Shutter Priority Mode
This mode (labelled S or Tv), is almost the opposite of Aperture Priority Mode. You can set the length of time that the camera’s shutter remains open, and the camera will automatically set the aperture to give a correct exposure. This mode gives you complete control over how much motion is shown in the photo.

It also gives you indirect control over the aperture, because as you set a shorter shutter speed, the camera has to open up the aperture to compensate for the lower light levels (and vice versa). Once again, you won’t have precise control over the aperture, because the camera is constantly altering the aperture based on the light levels.

This mode is good for when you want primary control over the amount of motion shown in the photograph, such as sports photos or streams and waterfalls. Again, I’ll go into more detail later on.

Manual Mode
This is the ultimate of all modes. In this mode you have direct control over both aperture and shutter speed, meaning you can set the exposure very specifically. There’s not really any of the pre-programmed modes (such as sports mode or portrait mode) that equate to manual mode.

When using manual mode, the camera doesn’t set anything itself. This means that you are able to over-expose or under expose the image. However, the camera will display a basic light meter on the back. As long as the little marker is in the middle, you’ll get what the camera thinks is a good exposure.

If you’re using manual mode, it’s well worth understanding how shutter speed and aperture affect the image. It’s also worth knowing how to altering the exposure settings while still keeping the same exposure. That is too long to go into, but my tutorial on shutter speed, aperture and ISO explains this. You can find it here: [link]

Using manual mode is also rather time consuming, as you have to set both aperture and shutter speed. Thus, this isn’t the best mode to use when walking around waiting for a photo to pop up. By the time you’ve set the correct exposure, the opportunity is likely to be gone. However, if you have enough time to set the correct exposure, then this mode is going to give you the most flexibility.

Using P, A, S and M Modes

In this section, I’ll be discussing the common point and shoot modes available on nearly all cameras, explaining how the setting are changed for each of them, and explaining how to create the same settings using P, A, S and M modes. The purpose of this is to allow you to create the same results that the pre-programmed modes will give you, but with the options of taking greater control. Bear in mind that these pre-programmed modes may also involve settings such as white balance that aren’t directly related to exposure. Where applicable, I’ll include these as well.

If you have an older film SLR that doesn’t have these modes, you’re basically stuck on full time manual mode. To use these settings, set the shutter speed or aperture as described, and then adjust the other to give a proper exposure.

Portrait Mode
The pre-programmed portrait mode is designed to give nice skin tones and keep the background out of focus to make sure the subject stands out.

To re-create this mode, set the camera to Aperture Priority Mode and set the aperture quite wide; that is, a low number. The exact number will depend on the lens you are using, although the popular 50mm f1.8 lens is good for this. The wide aperture will create a narrow depth of field that will make sure that the background is out of focus. However, there is the risk that the depth of field will be so narrow that you won’t be able to get the person’s entire face into focus. To avoid this, set your aperture to about f2.8 or f4. You can emphasise the blurriness of the background by stepping back and zooming in. Setting a wider aperture (lower f number) will make the background even blurrier, while setting

Also, you can adjust the white balance to give slightly warmer colours in the picture. If you’re outside on a sunny day, for example, set the white balance to “Cloudy” instead of “Daylight”. This will give a slightly warmer cast to the picture.

Two final tips: Focus on the eyes. Always on the eyes. Also, if there are shadows across the subject’s face, turn on your flash. This will help to bring a bit of details

Sports Mode
The pre-programmed sports mode is designed to allow you to capture fast moving subjects, such as people running.

To re-create this mode, set your camera to Shutter Priority Mode and set a fast shutter speed. However, note that as you set a faster shutter speed the camera will have to open the aperture to compensate, and once the aperture is as wide as it can get, you’ll be underexposing the picture if you set the shutter speed any faster. This may be acceptable, and you are often able to correct a slight under exposure in Photoshop. You may also want to increase the ISO to allow for a faster shutter speed, although this will increase the grain in the photo. Fortunately, dSLR cameras don’t produce noticeable amounts of noise until about ISO 800 or so.

Landscape Mode
The pre-programmed landscape mode is designed to let you take photos of landscapes and large buildings while keeping as much as you can in focus.

To re-create this mode, set your camera to Aperture Priority Mode and set the aperture to a high number, such as f16 or f22. This will increase the depth of field, so that you can have a tree in the foreground in focus as well as keeping distant objects (such as a mountain range) in focus.

However, since you are using a small aperture, the camera will automatically set a rather long shutter speed, so you should use a tripod to eliminate camera shake.

Night Landscape Mode
This mode is similar to landscape mode, but it differs in that it is designed to be used when light levels are very low.

To re-create this mode, follow the same procedure as landscape mode. However, be careful. With low light and a narrow aperture, you can easily get shutter speeds of ten seconds, so don’t even try this unless you have a tripod or some other way of keeping the camera perfectly still. And you can ignore flash as well, because there’s no way even a studio flash could light up the entirety of the Louvre at night.

Night Portrait Mode
Very often when you take a photo of someone at night, you end up with a photo of them with that “Rabbit caught in the headlights” look, and a completely black background. Night portrait mode is designed to give a properly exposed subject while still keeping detail in the background. This mode is used when you are taking a portrait of a person at night or in a dark area when you want to keep details in the background.

To recreate this mode, set the camera to aperture priority mode and mount it on a tripod. Set the aperture to around about f8 or f11. This will make sure that the background is out of focus to keep the subject standing out a little, but it will also make sure that the background keeps some detail to make sure you can still tell what it is.

Next, set your camera’s metering mode to evaluative metering. This will make sure that the camera looks at the entire frame to determine the correct exposure, rather than just a small area at the center. Press the exposure lock button. This will lock the exposure to keep detail in the background. If your camera doesn’t have an exposure lock button, look at the shutter speed and aperture, remember them, then set your camera to manual and enter those same values.

Next, turn on the flash and focus on the subject.

Now, take the photo. If you’ve done it correctly, the camera is doing several things at once. It is exposing for the background to make sure that it has detail and isn’t black. It is focussed on the subject instead of the background so that the subject is in focus, and the depth of field will blur the background enough to make the subject stand out from the background. And the camera uses the flash to make sure that the subject is lit up.

You may need to adjust the flash power to avoid an over-exposed subject – see you camera’s manual for instructions on how to do this. Also, because the camera is using a slow shutter speed to keep the detail in the background, a tripod is essential. Also, tell your subject to keep still – if she moves after the flash has gone off but while the shutter is still open, there will be detail from the background visible through her.

Fireworks Mode
I’ve covered the camera settings for fireworks and lightning in my Basic Exposure Settings tutorial: [link] However, to save you from going to it, I’ll repeat what I said there.

For fireworks, try a film speed of ISO100, with a shutter speed of 8 seconds and an aperture of f8. Digital cameras are particularly good for this, because you can check your results as you take the photos and make any adjustments as needed. A tripod is essential for this type of photography, due to the very long exposure time. Also, fireworks photography is often actually several exposures that are combined together to give plenty of fireworks in the image while avoiding any light glare from a single long exposure. Use manual mode for this situation, or the camera may try to expose for a dark sky instead of fore the bright burst of the fireworks. Remember, the actual burst lasts only a second or two. If you use program, Aperture or Shutter modes on your camera, the burst will be over by the time the camera meters off it. Also, set the lens to manual focus mode and set it to focus on infinite, or you’ll lose the shot as the camera tries to focus on the brief burst of the fireworks.

Lightning is similar to fireworks photography, but is a bit trickier, because you aren’t just dealing with the light from the lightning bolt, but also from the cloud that is being lit by the lightning. Try a ten second exposure on ISO100 film with the aperture at f5.6. Be warned, however, that there is no guarantee when a flash will occur, so the best way to get a good shot is to take photo after photo after photo. To get the shot of lightning in my gallery (The Storm #2 [link]) took me about half an hour and 50 shots. A tripod is essential due to the long exposure time, a remote release (either cable or infrared remote) makes it much easier, and also set the camera to manual mode and the lens to manual focus for the same reasons described in the section on fireworks. Again, check your photos and adjust your exposure as required.

Snow/Sand Mode
The pre-programmed sand or snow mode is designed to give a proper exposure when you are taking photos where sand or snow makes up a large part of the image.

This mode isn’t so much about shutter speed or aperture, but about exposure compensation. Digital SLR cameras will have an exposure compensation function, but it won’t work in manual mode, for reasons which I will explain below. If you don’t, you’ll have to set your camera to manual mode.

Exposure compensation is required because snow and sand are more reflective than average. The camera expects a scene to reflect about 18% of the light that falls on it. That’s about the same as concrete or Caucasian skin. However, snow and sand reflect a lot more light than this. If the camera doesn’t know, then it will think that the brightness is caused by a very bright light, and decrease the exposure to compensate. This, of course, gives an under-exposed photo, with snow looking a sickly grey.

Exposure compensation allows you to make corrections to the exposure that the camera thinks is correct. Increasing the exposure compensation will brighten the image, and decreasing the exposure compensation will darken the image. This will work in P, A and S modes, but it won’t work in manual mode. This is because exposure compensation is designed to adjust the settings that the camera decides on, and in manual mode there are no settings the camera decides on. If you are in manual mode, you can easily do the same thing by using a faster shutter speed to make the image darker and a slower shutter speed to make the image brighter.

So, if you are taking photos in a snowy or sandy location, set the exposure compensation to over-expose the photo a little bit, generally by a stop or two. Review the picture afterwards to make sure that the picture has come out. As always, you may be able to correct the exposure in Photoshop afterwards.