Photography terms (Aperture, ISO, Flash Sync, etc.)

Digital cameras have come on a long way in the past few years with new features being added all the time. Some recent features include image stabilisation, face recognition and smile and blink detection. However, no matter how user-friendly a camera may be, things can go wrong even in the supposedly foolproof “Auto” mode if let’s say a child playing with the camera sets the capture resolution to VGA (0.3 Megapixel) mode!

As every manufacturer has their own menu layout, to start with, we strongly recommend having at least a quick look at the camera’s user manual to get familiar with its menu layout where the various settings are located in menus and which can be directly accessed directly as buttons.

In this guide, we’ll start by explaining the main features that affect the exposure, framing and colour reproduction in a photo. Even if you mainly plan using your camera for point & shoot and let the camera automatically controls its settings, these are still worth reading about to help troubleshoot when things go wrong, as there is no point reading about the problem when the photo opportunity has gone! For example, one would feel bad if they threw away a perfectly good camera over bad pictures only to find that they could have used taken all those shots if they knew what to adjust to make them come out.

Note: Some cameras, especially DSLRs and prosumer models have a very wide selection of features, so this guide only covers the main features that are found on most digital cameras.

Photography Terms

Quality / Megapixel

This specifies the number of megapixels to record and how much to compress the picture and is also the most important setting to be careful with as it can be changed on the “Auto” mode on nearly all cameras!

This setting should be set to the highest Megapixel and quality mode available. For example, on a 12 Megapixel camera, this would be something like “12M Fine”. The number specifies the number of recorded pixels, so as an example the 3M setting would mean that the camera will record a 3 Megapixel picture. The word after this specifies what type of compression will be applied. The “Fine” mode applies the least compression and retains the most detail, where as the “Coarse” mode (if available) applies the most compression to fit as many pictures as possible on the card at the cost of detail being sacrificed. Some cameras use other terms, e.g. “Basic” for the highest compression mode on Nikon cameras.

Note: Unlike the early days of digital cameras when many models had under 2 Megapixel sensors, the megapixel rating no longer plays a significant role in how much useful detail the camera can capture, except in cameras with extra large sensors such as DSLRs and medium/large format cameras used in photo studios. The problem is that as more pixels are crammed onto the tiny sensor, the less light each individual pixel sensor picks up, thus leading to more noise in the picture. For example, on a bright sunny day, a 14 megapixel compact may pick up more detail than a 6 megapixel compact, but on a low light shot such as a cloudy day, the 6 megapixel compact will pick up more detail than the 14 megapixel compact due to amount of noise that will end up in the photo of the higher megapixel model.

Flash / sync

While most are well aware that a flash is used for taking photos indoors and in low light, most cameras have several flash settings to choose from. These settings typically include off, auto, forced, slow sync and rear/curtain sync.

The “Off” setting prevents the flash being fired regardless of how little light is present. This is useful for taking photos in places where a flash is prohibited, such as museums, aquariums or where the flash is unwanted such as taking photos of fireworks.

Most cameras have the flash set at “Auto” by default such that the flash only goes off when the light falls below a certain threshold or where the camera cannot set the shutter speed high enough to ensure a steady handheld shot.

The “On” setting is typically used to reduce or remove shadows in photos such as when taking photos in direct sunlight to reduce shadows in the subject’s eyes. This is also known as a fill-in flash.


No flash (left) vs Fill-in flash (right)

Slow and rear/curtain sync are available on some cameras to allow for motion to be captured in the shot. With slow sync, the flash is fired at the start of the exposure and in rear/curtain sync, it’s fired at the end of the exposure. Rear/Curtain sync tends to capture the motion better for moving objects as the motion captured leads up to the “freeze frame” at the end of the exposure when the flash is fired.


Rear sync flash

Note: On some cameras, the flash cannot be set to “Off” on the “Auto” mode. As a work around, set the camera to its ‘P’ mode, set the flash to “Off” and ensure the other settings such as ISO are set to “Auto”. Alternatively, if the mode dial has a ‘No Flash’ setting, use this instead of the auto mode.

Shutter speed

When a picture is being taken, the shutter will open to expose the sensor for a certain amount of time. The slower the shutter speed, the longer it remains open for and the more light taken in. A slower shutter speed is usually required for low light photography, but the slower the shutter speed, the more susceptible the image is to blurring from camera shake.

The shutter speed is measured as a fraction of a second, such as 1/125th second. Most cameras can control the shutter speed to between several seconds and several thousandths of a second. On models where the user can choose the shutter speed, it goes up/down in steps of double/half, e.g. 1/30ths, 1/60ths, 1/125ths and so on.

Besides low light, photographers will often use slower shutter speeds to show a motion effect in the photo, such as a water fall or even a ball in flight in a game. Faster shutter speeds are used to stop motion, such as to capture a bird in flight.


Fast shutter (left) vs slow shutter (right) of flowing water

When a camera is in any mode with automatic shutter speed, it will try to ensure that the shutter is set at a speed to allow the most light in for low light photography while also minimising handshake. A camera with image stabilisation will generally automatically choose lower shutter speeds than cameras without image stabilisation.

Note: Most compact point & shoot cameras do not have manual shutter speed control, so if you plan on getting a camera to take long night time shots or would like control over the shutter speed for special occasions, check that the camera has shutter priority control. For long exposures such as night time photography, it is worth checking what the longest exposure setting is available.

Aperture

The aperture controls the amount of light reaching the sensor, where a larger aperture opening means more light reaching the sensor.

The aperture is measured in F-stop numbers, typically in multiples of 1.4, where each 1.4 times increase in the F-stop number means doubling the amount of light let in. The lower the F-stop number, the larger the aperture opening. So a lens with the aperture set at F2 will let in twice as much light as when the lens is set at F2.8. The maximum aperture (lowest F-stop number) available depends on the lens and the zoom setting.

On cameras with large sensors (such as DSLRs), the aperture also has a very significant effect on depth of field, which is how much the foreground and background are blurred while keeping the subject in focus.

Most cameras have the maximum apertures printed on the lens, e.g. F1:3.5-5.6. The first number specifies the maximum aperture (minimum F-stop number) that can be used with the lens zoomed to the widest angle. The second number specifies the maximum aperture that can be used with the lens zoomed to its most telescopic setting.


Focal range & aperture values printed on Fujifilm F30 lens

As a lower aperture F-stop number means more light let in, it’s worth taking this into account when choosing a camera, even if you’re not interested in being able to manually control the aperture. This is more important when it comes to ultra-zoom cameras as the wider aperture the faster the shutter speed that can be chosen for the same exposure. For example, decreasing the aperture from F2.8 to F2.0 allows the shutter speed to be doubled for the same exposure. Some DSLR lenses, especially prime (fixed focus) lenses, feature very wide apertures. For example, an 85mm F1.4 telephoto prime lens will allow a 16 times faster shutter speed than another telephoto lens with a maximum aperture of F5.6 at 85mm.

Note: Like with the shutter speed, most compact point & shoot cameras do not have manual aperture control, so if you need to be able to control depth of field, we would suggest going for a camera with this control and also with as large sensor as possible. Most low cost, ultra compact and long (10+x) zoom cameras have such a small sensor where adjusting the aperture has very little effect on depth of field.


F8.0 (left) vs F2.8 (right) on Panasonic DMC-LX3 compact

ISO Speed

This controls the sensitivity of the sensor, much like the speed rating of film. The higher the ISO, the move sensitive the sensor becomes to the incoming light.

Like film speeds, the ISO rating is typically measured in speeds of 100, 200, 400 and so on, where each doubling of the ISO figure means doubling the sensitivity. For example, increasing the ISO from 100 to 400 allows the shutter speed increased 4 times for the same exposure. However, just like film, the higher the ISO rating chosen the more degraded the picture will be.

As the sensor itself is an analogue device, increasing the sensitivity is the equivalent to amplifying the signal each individual sensor (pixel) picks up and the more amplification applied the more noise that will be present. This issue is more noticeable in smaller sensors (such as most compacts) where the individual pixel sensors pick up less light than those in larger sensors (such as in DSLRs.)


Crop of photo of calender image at ISO 1600 from
Panasonic DMC-LX3 compact (left) & Nikon D60 DSLR (right)

Ideally, the lowest ISO speed available should be chosen for the best quality picture. However, when it comes to low light photography where the aperture cannot be opened any further, the ISO speed can be raised to allow a faster shutter speed to reduce blurring from handshake.

Note: Unlike the shutter and aperture, most compacts that lack these settings do allow the user to choose the ISO speed when the camera is set to its ‘M’ or ‘P’ modes. When in the automatic mode, the camera sets the ISO speed automatically to ensure the shutter speed is high enough for a good quality handheld shot.

Marketing note: Some manufacturers are advertising cameras with exceptionally high ISO speed ratings to make their cameras stand out on sensitivity, however, in most cases, all the higher ISO speed setting does is lead to an even more degraded picture. Very few compact digital cameras can take a photo at higher than ISO 800 with a noise-free 4x6” (10x15cm) print, including compact cameras with ISO sensitivity claims of up to 12800!

Exposure compensation

When taking a photo containing a bright or dark background, the exposure compensation controls how much darker or brighter in F-stops.

The exposure compensation is typically measured in steps of 0.3ev, where each 1ev is the equivalent to 1 stop compensation. A 1 stop increase is the equivalent to doubling the exposure.


Koi in aquarium at normal exposure (left) and -1ev adjustment (right)

Note: This setting is usually available on all modes with most cameras. After the setting has been adjusted for a photo, it should be set back to 0ev, otherwise the exposure compensation will be applied to each photo taken afterwards until the setting is reset.

Metering

By default, the camera will adjust the exposure based on an average of the entire frame. However, if the subject being photographed is small and is placed against a bright or dark background, such as someone skiing, it may be necessary to set the camera to centre weighted or spot metering.


Average metering vs. spot metering of tree against a bright sky

White Balance

Our eyes automatically compensate for changes in white balance such that colours closely resemble what they would look like under a true white light source. Digital camera sensors on the other hand capture the scene exactly how it is, so the camera software needs to correct the white balance to make the picture appear as to how we would see the scene in real life. For example, a photo taken in a room with a traditional filament (non eco-friendly) light bulb would appear quite yellow without while balance correction.


Tungsten vs. cloud white balance setting of indoor lighting

On most cameras, the white balance can be set to automatic, tungsten light, fluorescent light, sunny, in the shade or clouded over. Some cameras also have a manual white balance, where the camera can be pointed on a white or grey sheet and the camera adjusts its white balance to compensate for the light used in this area.

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