Camera functions and controls

Is there any reason not to use the basic (picture icon) modes of my camera?

Yes. The icon modes are great for beginners but teach you nothing about how to use your camera. Each mode contains a set of assumptions and computer programs that Canon’s engineers think will cover the various types of shooting conditions reasonably well.
But if you want more control over your camera’s operation - and thus over how your photos will turn out - you’ll need to explore the letter modes of your camera as described in the next section.

What do the various letters (P, Tv, Av, M, C, etc) on the command dial mean?

These letters let you choose specific automatic exposure (AE) methods. They’re referred to as “creative zone” modes by Canon, since absolute beginners are expected to use the icon (“image zone”) modes instead. The creative zone modes give you greater control over the operation of the camera, however, and are thus more appropriate for more experienced photographers.

Program AE mode (P).

When your camera’s command dial is set to to

P

the camera will automatically select both shutter and aperture settings for you according to its built-in basic program. It’s similar to the green rectangle mode in this respect.

Unlike the green mode you can often adjust exposure compensation, AF, film winding and metering modes in addition to supporting AE lock, exposure bracketing and multiple exposures, depending on the model.

Shutter priority AE mode (Tv).

In this AE mode you set the shutter speed (time) by rotating the main dial located next to the shutter release button. The camera will then automatically set an appropriate lens aperture for you.

Tv

stands for “Time value.”

Use this mode if specifying the shutter speed is important. For example, you may want a fast shutter speed to freeze motion or a slow shutter speed to blur it.

Aperture priority AE mode (Av).

In this AE mode you set the lens aperture by rotating the main dial located next to the shutter release button. The camera will then automatically set an appropriate shutter speed for you.

Av

stands for “Aperture value.”

Use this mode if specifying the lens aperture is important. For example, you may want a large aperture for better low-light shooting or narrow depth of field. Or a small aperture for wide depth of field.
Metered Manual mode (M).

In this mode you set both the lens aperture and the shutter speed completely manually. If your camera has a rear (back panel) dial then you set the shutter speed with the main dial and the aperture with the rear dial. (or vice-versa, if your camera lets you reverse the dials) If your camera has only a main dial then you have to press and hold a rear button in conjunction with rotating the main dial.
The camera will assist you by telling you whether it thinks you have the correct metering. Some older EOS cameras display little

+

and - arrows telling you whether your picture is correctly exposed, overexposed or underexposed. Other models display a little animated slider bar with a dot indicating the current exposure setting; a simulated matchneedle. If the dot is exactly in the middle then you’re using the setting that the camera believes to be correct metering.
Depth of field mode (DEP and A-DEP).

These modes allow you to concentrate on the depth of field - the area in the picture in which stuff is in acceptable focus. For more details on these modes see the DEP/A-DEP section below.

Custom mode (C).

The custom mode is to be found on many Canon point and shoots and some newer digital EOS cameras, starting with the EOS 5D. Custom is essentially a dial setting which allows you to roll your own icon mode. You set the characteristics you need for the camera (aperture priority with second curtain sync and spot metering, for example) and store the setting. Then you can switch your camera over instantly to those settings by turning your camera to the C function. This can be very useful for rapid access to normally hidden camera functions, such as mirror lockup.

How can I find out what all the icons and acronyms on my camera mean?

I have an online photographic dictionary which lists the most common camera icons and acronyms if you’re interested.

What is the difference between DEP and A-DEP modes?

DEP stands for “depth of field automatic exposure” and A-DEP stands for “automatic depth of field AE”. Both modes will choose a shutter speed and aperture combination to let you achieve a certain depth of field effect, but they do so differently. Most EOS cameras have either DEP or A-DEP modes. However one model, the 10/10s, has both and some newer digital bodies, such as the EOS 1D mark II and the 5D, have neither.

DEP.

To use DEP, first autofocus on a foreground item within your desired depth of field by selecting the subject and pressing the shutter halfway. “dEP 1” will appear in the viewfinder. Then recompose the image and autofocus on a background item by selecting the subject and pressing the shutter halfway. “dEP 2” will appear in the viewfinder. Finally, compose the final image in the viewfinder and press the shutter release halfway again. The camera will then calculate the necessary aperture setting and shutter speed to keep both items, and everything in between, in focus. If this isn’t possible then the camera will blink a warning. If your camera has multiple focus points do not change the selected focus mark at any stage during this process. Press the shutter release all the way to take the photo.

A-DEP.

A-DEP requires multiple focus points and so is never available on any EOS camera with only one focus point. In this mode you arrange your image in the viewfinder such that a foreground item within your desired depth of field is covered by either the left or the right focus mark, and that a background item is covered by one of the two remaining focus marks. Press the shutter halfway and hopefully two focus marks will light up in the viewfinder telling you which items were chosen. The camera tries to set the aperture and shutter speed such that everything between your two selected points is in focus. If it’s not possible for that to happen then the camera will blink a warning at you. If it is possible then neither the aperture nor the shutter speed will blink and you can press the shutter all the way to take the photo. A-DEP, as its name implies, is more automated and also affords less control than DEP.

What is bulb (B) mode?

Camera shutter times are normally specified in fractions of a second. Taking pictures on a sunny day, for example, can easily mean extremely brief exposures of 1/60 to 1/1000 of a second. But what if you want to take really long exposure photographs - perhaps several minutes - at night?

Most cameras don’t have a way to dial in extremely long (longer than 30 second) exposures. Instead the camera has what is known as “bulb” mode. To enter this mode on most EOS cameras you set the camera to manual metering (M) and then set the shutter speed to “buLb”, which is usually the setting past 30 seconds. With some cameras you set the camera to B mode. Either way, in this mode the shutter will remain open for as long as you keep the shutter release button pressed down.

You then set a stopwatch or something and time the exposure manually. More conveniently, some recent EOS bodies have a top-deck timer so you just need to turn on the LED backlight and you can watch the seconds tick by. There are three obvious problems with this way of exposing film. First, if you press and hold the shutter release button on the camera body itself there’s a very good chance that you’ll inadvertently bump the camera slightly and risk blurring the exposure. Second, it can be really tedious holding down the shutter for a long period of time. And third, metering can be tricky.

The first two problems are easily addressed by using a remote shutter release. Most EOS cameras take optional wired shutter releases which plug into small sockets on the side of the camera. These accessories let you trigger the camera shutter without physically touching the camera. Several EOS cameras also support an optional wireless release which lets you trigger the camera by pointing a small device at it. The shutter release command is sent to the camera via pulses of invisible infrared energy. For more information have a look at the section on remote shutter releases.

Wired remote releases also typically have lock mechanisms, making it much easier to take a long exposure. Wireless remotes on EOS cameras also work well with long exposures, since one press of the remote button opens the shutter and a second press closes it. (this is analogous to the “T” or Time exposure mode used in many older cameras)

The exposure problem is different. Ordinary light meters inside cameras can’t really meter for extremely low light levels, so metering for long exposures is essentially a matter of trial and error. It’s best to settle on one type of film and a fixed aperture choice and learn what shutter speeds work well for you. Astrophotography of stars and such can easily involve exposure times in the hours.

Incidentally, bulb mode is so named because in the olden days of purely mechanical cameras remote shutter releases were typically rubber bulbs linked to the camera via hoses. Squeezing the bulb pushed a mechanical lever at the end of the hose, pressing down the shutter release. The use of the term on modern computerized cameras is an anachronism.

What do the various metering modes and icons mean?

Canon cameras support a number of different ways of metering light coming in through the lens. The midrange and professional models let you choose which metering mode you want, and consumer cameras generally default to evaluative in most settings with partial as an override option. Here are the various metering modes.

Evaluative metering.

Evaluative metering is the most automated metering mode. In this mode the image is divided into a number of zones - usually 3, 6, 16, 21 or 35. The camera’s computer then looks at the metering zones and applies various algorithms (computer programs, essentially) to guess a likely exposure setting. It then chooses appropriate shutter and/or aperture settings based on these calculations. Unfortunately, Canon have not published details of how these algorithms work. Nikon, incidentally, call this type of metering “matrix metering,” and sometimes people use the term “matrix” to refer to all forms of multiple-cell computerized light metering. Evaluative metering usually works reasonably well, though the meter can often be fooled by extreme metering conditions - such as a person backlit with a bright light. A larger number of metering zones does not, however, necessarily mean improved metering. Some cameras with 6 metering zones can meter just as well or as reliably as another model with 35 - it really depends on the camera model. Evaluative metering is convenient but, since it’s so automated, doesn’t teach you much about the fundamentals of metering.

Evaluative metering is identified in midrange and pro EOS models by the [(*)] symbol.

Spot metering.

Spot meters examine a very small area (a spot) of the overall image - usually just 1% or 2% or so. They’re popular with experienced photographers who select an area that they want to appear as light grey on the final image and use that to meter from. Spot metering is an essential tool for metering in challenging light situations, but is harder to master from the point of view of the novice. Only professional and semi-professional EOS models offer spot metering. Some also offer multi-spot metering, which allows you to select multiple spots and then average out the readings. Spot metering is identified in midrange and pro EOS models by the [ * ] symbol.

Centre-weighted averaging metering.

This mode essentially simulates the typical metering mode used in cameras sold in the 1970s. Such cameras average the total amount of light coming in across the whole image but give a bit more importance (weight) to the centre. Unfortunately Canon do not publish the weighting percentage and weighting diagrams for most of their cameras, so only experience will tell you how this mode works. Though technically simple, this metering mode works well for images which have relatively little variation in light level across the scene. A classic example might be a landscape on a sunny day. The sky at the top will be fairly bright, but since the metering is centre-weighted the bulk of the scene should be metered correctly.
Centre-weighted averaging metering is identified in midrange and pro EOS models by the [   ] symbol.

Partial metering.

Very similar to spot metering, only a larger area of the image is used - typically 6.5%, 9.5% or 10%, depending on the model. Think of partial metering as a very fat spot. Some cameras with multiple focus points tie the area to be metered to the currently selected focus point. Partial metering is good for giving you more control over metering results. For example, let’s say you’re trying to take a photo of something which is surrounded by darkness. Evaluative metering might be a problem as it might be thrown off by all the dark areas. With partial you can select a section of your image that you want to be medium grey and then you don’t have to worry about the meter being fooled by the stuff around it.
Partial metering is identified in midrange and pro EOS models by the [(  )] symbol.

Does the number of metering zones matter?

There’s quite a variation in evaluative metering zones across the Canon EOS lineup. Some cameras meter from three zones, some from six, some 16, some 21 and some 35. And Canon have generally been increasing this number over the years.

The immediate assumption one can make is that the more zones the better. But that’s not necessarily the case. Many other factors come into play - the speed of the camera’s internal computer, the sophistication of its algorithms (computer programs) and so on. Given the choice between a low-end camera with a ton of metering zones and a midrange or pro camera with a handful of metering zones I’d go for the latter any day.

In short, while metering zones are important I personally wouldn’t make a purchasing decision based on the number of evaluative metering zones a given camera has.

What does Single versus Continuous wind mean?

EOS film cameras all contain motorized film-winding mechanisms. How the camera winds film depends on the mode you’re in. Note that not all EOS cameras have a specific control for choosing wind modes, but most do. If your camera lacks the ability to choose winding modes remember that each icon mode is associated with one or other of the winding modes. So if you need a specific winding mode you might look up which mode uses which mode.

Single frame.

In single-frame wind mode the camera will shoot one picture each time you press the shutter release button. Nothing happens when you continue to hold down the button. Single-frame mode is usually identified by a rectangle icon. Use this mode for shooting something static, such as a landscape. For this reason the landscape icon mode uses single frame winding.

Continuous.

In continuous wind mode the camera will shoot as many frames as it can for as long as you hold down the shutter release button. Until you run out of film or storage space, of course. The shooting rate depends on both the motor-drive speed of the camera (anywhere from 1 to 10 frames per second, depending on the model) and which autofocus mode the camera is in. Continuous wind mode is usually identified by an overlapping rectangle icon. This mode is useful for shooting rapid-fire pictures of something. For example, an exciting moment in a sports tournament or a speech by a famous politician might both be moments when you want to shoot a lot of frames in the hope that one will turn out well. For these reasons the sports and portrait icon modes use continuous frame winding.

What are the One-Shot and AI Servo autofocus modes?

Most EOS cameras support three autofocus modes - One-Shot, AI Servo and AI Focus. Midrange and professional EOS cameras let you choose which mode the camera is in, often via controls marked in yellow.

However, low-end EOS cameras do not let you choose these modes directly. Instead, each of the basic modes is preprogrammed to use one of the three autofocus modes. So you can sort of choose your autofocus mode indirectly by choosing a basic mode that happens to have the autofocus mode you want to use.

One-shot AF (autofocus).

In this mode the camera locks in on your subject and doesn’t refocus once you’ve achieved focus. It won’t take a picture unless you’re in focus or unless the lens is in manual focus mode. It’s good for shooting static subjects.

AI (“artificial intelligence”) servo mode.

In this mode the camera tries to keep refocusing the lens as you track your subject. The exposure is determined when the shutter release button is fully depressed in both single and continuous winding modes. AI Servo is supposed to be able to track subjects moving to or from the camera - a feature called predictive focus. Since it requires a lot of computer power to do this all accurately, generally speaking newer models do a better job of this focus tracking than older models. It’s a useful feature for shooting moving objects, but again more with faster cameras than slower older ones.

AI Focus mode.

In this mode the camera starts in One-Shot mode but switches automatically to the AI Servo mode if it detects subject motion.

What camera setting should I use for a wedding? Landscape? Birthday party? (etc)

Unfortunately it doesn’t work like that. There are no magic settings and formulae for choosing camera settings. You have to learn what the various settings do - and the right time to use them - through experience.

For this reason I don’t recommend the basic (icon) modes if you’re interested in learning photographic technique. In the icon modes the camera makes all the decisions for you and you have no idea what internal settings it actually used. I’d recommend sticking to the four creative zone modes (P, Tv, Av and M) and reading up on photographic technique. Many libraries and bookshops have some excellent books that can help you with this. Many of them date back to the 70s and 80s, during the heyday of amateur photography, but the techniques they describe are still fundamentally applicable today.

What is exposure compensation?

The camera isn’t always right when determining the proper exposure for a photograph. Sometimes for technical reasons - the camera’s internal light meter might be fooled by a bright light, for example. And sometimes for artistic reasons - the camera is only a machine and doesn’t know what areas of a picture you consider particularly important.

So for that reason most EOS cameras have a way of overriding the exposure setting determined by the camera. This is quite often implemented via a rear command wheel which you can rotate to select the number of stops of light to be added or taken away from the camera’s default measurement. EOS cameras which lack a rear command wheel, such as low-end EOS models, usually allow you to apply exposure compensation by pressing a back-panel button and rotating the main command dial.

For example, since camera light meters assume you want everything to be a medium-light shade of grey it can be a real problem taking a photograph under bright conditions. The classic example is the photo of the white dog standing in white snow. A photographer might apply a stop or two of positive exposure compensation. This additional exposure time means that the dog and snow should appear white in the final photo, not grey.

Note that in addition to regular exposure compensation, which involves compensating for the metering of ambient light, most midrange and better EOS cameras also feature flash exposure compensation (FEC). FEC allows you to adjust the light output from a flash unit, and does so independently of the ambient light metering.

What is a custom function?

Canon’s midrange and pro cameras - as well as their best flash units - have custom functions, which are user-controlled settings that let you customize the camera somewhat and access special features. For example, some people like using first-curtain sync flash and some people prefer second-curtain sync flash. Many EOS cameras have a custom setting which lets you choose the option you prefer. None of Canon’s consumer cameras have custom functions.

Unfortunately all EOS film cameras just number their custom functions, so there’s no way of knowing what the various custom functions do without consulting the manual. Alternatively, Photozone.de maintains a list of all the custom functions for EOS cameras which have them.

I set a custom function but it has no effect. What’s wrong?

Custom function settings are ignored if the camera is in a basic (icon) mode. You have to turn the camera’s mode dial to one of the advanced or “creative” zone letter modes, such as P, Tv, Av or M. So if the camera exhibits its default behaviour (eg: using first curtain sync rather than the second curtain sync that you’ve set using a custom function) be sure to check which camera mode you’re in.

What is leader out?

Normally film is spooled all the way back into the canister when a motordrive-equipped camera like an EOS film camera rewinds film. This is usually a good thing, as it’s then easy to identify the canister as being used.

However there are times when you might want to leave a tongue of film protruding from the canister when you rewind it. For example, perhaps you want to change rolls of film in the middle - maybe going from colour to black and white - and then you want to reload the partially used film later. If the film leader is out then this is pretty easy to do.

Most midrange and high-end EOS cameras have leader-out as a user-configurable option, set using a custom function. And, as custom functions are ignored in icon modes, this functionality only works in the creative (letter) modes.

How can you change films in the middle of a roll?

Nearly all EOS film cameras have a pushbutton or setting which causes the camera to rewind the film back into its canister immediately, even if the roll is not fully exposed. If there’s a button it’s usually recessed to avoid accidental pressing and is marked with a film canister with two arrows pointing into it. A few older EOS cameras require bizarre antics to rewind midroll, such as removing the lens, setting the camera to ISO and pressing the two back buttons.

However, unlike APS, 35mm film has no way to record the total number of shots used on a roll. There is no automatic way to switch films midroll and have the shot count recorded if you’re using a 35mm film camera.So if you decide to rewind a roll of film midway through for later use then you will have to write down the framecount so you don’t double-expose the film. Black fine-tipped indelible markers are good for this - you can write this number directly onto the canister itself.

To reload the film to the correct position use the following procedure.

• Load the previously partially-shot film.
• Cover the lens with a lens cap (or a body cap if you have no lens installed).
• Set the lens to manual focus, if it’s an autofocus lens, so that the camera doesn’t try to focus.
• Set the shutter speed to the fastest setting possible (eg: 1/2000 sec, 1/4000 sec) and aperture to the smallest (largest f-stop digit) setting possible (eg: f/22).
• Press the camera’s shutter release repeatedly and wind through frame by frame until the camera’s frame counter indicates the frame you noted down earlier.

Most modern EOS cameras use infrared diode positioning systems and are extremely accurate in aligning the film when you load it. So you shouldn’t need to shoot one additional blank frame to make sure there’s no overlap between the last frame shot the first time through and the first frame shot the second time through. However, if you have an older EOS camera with an electromechanical frame counter then you may need to add a blank frame for safety purposes. Check my article on infrared photography to see which type of film positioning system your camera uses.