Basics

Digital Camera

In a digital camera, the visible light that passes through the lens is converted into electrical signals by an electronic sensor. These electrical signals are then processed inside the camera by a processor and stored on a memory card.

Digital cameras offer a wide range of settings. Beginners mostly use the Automatic mode, where the camera handles all settings automatically. This usually results in a usable picture, but rarely one with a “wow” effect.

A distinction is made between:

Compact cameras, where the lens is permanently built-in, and
System cameras, where you can interchange the lens.

Among system cameras, a further distinction is made between the older:

SLR cameras (DSLRs), where the image is reflected through the lens into the viewfinder, and
Mirrorless system cameras, which feature a display, and in some cases, an electronic viewfinder.

Sensor

The sensor of a digital camera is located inside the body. With some cameras that feature interchangeable lenses, you can see the sensor after removing the lens.

Do not touch the sensor!

The light from an object (person, pet, landscape, …) passes through the lens onto the sensor. The image on the sensor is upside down and is flipped by the processor before being saved. This is similar to our eyes, which also project upside-down images onto the retina that are only flipped right-side up inside the brain.

Fig. 3: Ray tracing path inside the camera. Nowadays, a lens consists of multiple elements.

The sensor consists of pixels, among other things. Many cameras have 6000x4000 pixels, which equals 24 million pixels, or 24 megapixels for short.

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Lens

A lens consists of one or more glass elements. It ensures that an image can be captured sharply.

A distinction is made between:

Wide-angle lenses, which provide a wide field of view, e.g., for landscape shots,
Standard lenses, which correspond to the visual impression of the human eye, e.g., for groups of people,
Telephoto lenses, which act like binoculars, e.g., for wildlife photos,
Macro lenses, which act almost like a microscope, e.g., for small insects.

Fig. 4: Lenses from various manufacturers and systems.

Lenses from different manufacturers and systems are not compatible.

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Focal Length

The focal length of a lens is specified in millimeters and can be found on the front of the lens.

A distinction is made between:

Prime lenses, which have exactly one fixed focal length, and
Zoom lenses, where the focal length can be adjusted.

Standard lenses have focal lengths around 50mm. Wide-angle lenses have shorter focal lengths, while telephoto lenses have longer ones. There are zoom lenses that cover a very wide focal length range from wide-angle to telephoto.

Fig. 5: An old lens with a 50mm focal length.

There are other numbers printed on the lens behind the focal length.

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Aperture

The aperture of a lens consists of blades that reduce the diameter of the opening in order to reduce the amount of light entering.

A large aperture opening (small f-number) lets a lot of light through the lens and is helpful:

When it is very dark,
When you want to isolate a subject, for example, to make the background behind a person appear blurry.

A small aperture opening (large f-number) lets little light through the lens and is helpful:

When it is very bright,
When you want to render a particularly large area sharp, such as in landscape photography.

The aperture is set either by turning the aperture ring on the lens or from the camera body. In automatic mode, the aperture is adjusted automatically by the camera.

Fig. 7: Schematic representation of aperture openings and f-numbers.

From one stop to the next, the surface area through which light passes is halved.

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Shutter Speed

The shutter speed indicates how long the sensor is exposed during a shot. This is controlled via a shutter mechanism. Shutter speed is specified in seconds. A common shutter speed that can still be captured sharply handheld is 1/100 s. If you are capturing moving objects, you must choose a very short shutter speed to get a sharp image.

Fig. 12: Toy car driving down an inclined plane, captured at 1/30 s. The motion blur is clearly visible.

Fig. 13: At 1/125 s, the slow-moving car is almost sharp.

Fig. 14: A speed of 1/250 s is sufficient to render the car sharply.

ISO

ISO stands for “International Organization for Standardization” and represents the sensitivity of the film material or the sensor in photography.
Standard films for analog cameras are available with sensitivity ratings from ISO 50 to ISO 800; on digital cameras, the ISO range extends from 100 to 12800 and beyond.

When you have loaded a film into an analog camera, you must set the ISO value on the camera so that the exposure metering works correctly.

Schematic representation of noise for different ISO values.

Fig. 15: Photo of the second hand of a wristwatch at ISO 125. The photo is almost noise-free.

Fig. 16: At ISO 3200, the noise is already clearly visible.

Fig. 17: At ISO 12800, the image becomes unusable.

These images were captured using a relatively small 1-inch sensor, and the crop is heavily enlarged. With a larger sensor featuring larger pixels, the result would naturally look better. Color noise is visible at high ISO values.

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Interplay of Aperture, Shutter Speed, and ISO

A “correctly” exposed image remains correctly exposed if:
- The shutter speed is reduced by one stop and the aperture is lowered by one stop (opened wider),
  - e.g., 1/60 s to 1/125 s and aperture f/8 to f/5.6.
- The shutter speed is reduced by one stop and the ISO is increased by one stop,
  - e.g., 1/60 s to 1/125 s and ISO 400 to ISO 800.
- The aperture is increased by one stop (closed down) and the ISO is increased by one stop,
  - e.g., aperture f/5.6 to f/8 and ISO 400 to ISO 800.

This allows you to control whether you want to isolate the subject (smaller f-number), render a moving subject sharply (shorter shutter speed), or keep image noise to a minimum (lower ISO).

Fig. 18: The most important aperture values, shutter speeds, and ISO ratings. Moving one step to the right in one row and one step to the left in another keeps the exposure identical. This naturally applies to unlisted intermediate values as well.

Focusing

In automatic mode, a digital camera usually handles focusing by itself. On most cameras, the shutter button has two pressure points. If you gently press the shutter button halfway down, it focuses; pressing it all the way down captures the photo.

On most cameras, there are at least two different autofocus operating modes:

One-Shot AF for stationary subjects, which focuses once when the shutter button is pressed halfway,
Servo AF (Continuous AF) for moving subjects, which focuses continuously while the shutter button is pressed halfway.

And different autofocus area modes:

Single Point, to focus precisely on one point,
Zone, to focus within a small area,
Automatic Area Selection.

With automatic area selection, the camera detects people and faces, selects the autofocus point independently, focuses on a face or even on the eyes, and tracks them through movement. The active autofocus point virtually “sticks” to the person or their eyes. However, this does not guarantee that it will sharply capture the grandchild rather than the grandmother. It is safer to select the part of the image you want to be sharp yourself. To do this, it is best to select the autofocus mode that provides exactly one center autofocus point and choose One-Shot AF. The autofocus point is displayed in the viewfinder and on the screen; hold the camera so that the autofocus point lies on the part you want to be sharp. Usually, this is a person, or in the case of close-ups, the eye of a person or animal. If the eye is not in the center of the frame, you can move the autofocus point using buttons or a joystick on some cameras.

Fig. 19: Looking through the viewfinder. The small red square is the active focus point.

Fig. 20: In the captured image, the focus sits perfectly on the eye.

Fig. 21: The automatic mode focuses on the front Ottifant.

Fig. 22: If you select the autofocus point yourself,

Fig. 23: you can focus on any of the other Ottifants instead.

The display of autofocus points varies between cameras. Some lenses feature a switch to activate autofocus. The entire focus control depends heavily on the manufacturer and the specific camera model.

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Depth of Field

Depth of field describes the zone of acceptable sharpness along the axis of depth.

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The depth of field is particularly deep with:

A small aperture (high f-number),
A short focal length (wide-angle lens).

And particularly shallow with:

A large aperture (low f-number),
A long focal length (telephoto lens).

Fig. 24: Deep depth of field. The entire animal is sharp.

Fig. 25: Shallow depth of field. Only the area around the eyes is sharp.

If you want to render as much of the scenery sharp as possible in a landscape shot, it is best to focus on an object located roughly one-third as far away from you as the most distant object you want to capture. If a mountain range is 1.5 km away in a mountain landscape, you will get a sharp image at apertures from f/5.6 to f/13 if you focus on a house, a church steeple, or a tree 500 m away. Then everything from about 25 m to the mountain range will be sharp. An even better result can be achieved by utilizing the so-called hyperfocal distance.

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Camera Modes

Most cameras feature additional modes alongside the automatic mode, where the camera handles everything itself. Camera modes make operating the camera easier without completely giving up control to the camera like in automatic mode.

The following modes are available on almost all system cameras:

Auto (Automatic) – Autofocus area, shutter speed, aperture, and everything else are determined by the camera.
P (Programmed Auto) – Shutter speed and aperture are determined by the camera.
Tv (Shutter Priority / Half-Automatic) – You set the shutter speed, and the camera determines the aperture to ensure the image is correctly exposed. This is useful when capturing fast-moving animals or vehicles to prevent motion blur.
Av (Aperture Priority / Half-Automatic) – You set the aperture, and the camera determines the shutter speed to ensure the image is correctly exposed. This is useful when you want to isolate a person (large aperture, small f-number) or capture a landscape (small aperture, large f-number).
M (Manual) – Both shutter speed and aperture must be set manually.

The names of the various modes can differ depending on the manufacturer. Many cameras feature additional special scene modes and filters.

Auto Exposure Metering

In the half-automatic modes (Tv, Av), you can influence the auto-exposure system by narrowing down the area that the system uses to determine the correct exposure. The following options are available:

Evaluative / Matrix, the entire visible frame is taken into account,
Center-weighted, only the central portion of the frame is taken into account,
Spot, only a small area around the active autofocus point is taken into account.

Fig. 26: Evaluative: the exposure was determined from the entire frame. Since the background is very bright, the animal was captured too dark.

Fig. 27: Spot: the exposure was measured around the eyes. The animal is now correctly exposed, though the background is very bright.

The exact areas considered in each mode can be found in your camera manual. The use of “Spot” metering should be chosen carefully, as image defects like ‘blown-out highlights’ and ‘crushed shadows’ can easily occur.

Exposure Compensation

By selecting the appropriate metering mode, you could ensure that the main subject is captured correctly while other parts of the image might end up under- or overexposed. When you capture a subject that is exceptionally bright overall, such as a snowy landscape, the image will turn out too dark in any standard exposure mode. Cameras without AI do not know that you are photographing snow. The camera assumes that the entire image features an average level of brightness—neither completely black nor completely white. If you want to shoot a snowy landscape, which is almost white, it makes sense to use manual exposure compensation. This forces the entire image to be captured brighter than the camera would make it on its own. The same applies to night shots, which are naturally darker than an average image.

This compensation is useful in the semi-automatic modes (Tv, Av):

For subjects that are very bright overall, like a snowy landscape or the daytime sky,
For very dark subjects, e.g., during twilight or inside a tunnel.

Most cameras are set up so that you can see the effect directly on the display or in the viewfinder and adjust the compensation accordingly.

Fig. 28: The shot captured with the exposure determined automatically by the camera.

Fig. 29: Compensation adjusted one exposure stop upward.

White Balance

White balance determines what is defined as “white” in the image. This depends heavily on the incoming light. The exact same subject looks entirely different at noon in bright sunshine than it does during sunset. Cameras can only get this approximately right automatically. That is why you can adjust the white balance manually on almost all cameras. For starters, it is usually enough to let the camera determine the white balance automatically (AWB, automatic white balance). Sometimes, an altered white balance looks more pleasing.

Fig. 31: White balance set for cloudy conditions. The colors appear warmer than in reality.

Fig. 32: White balance set for artificial light (tungsten). The colors appear cooler than in reality.

If you shoot in RAW format, you can alter the white balance afterward.

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Camera Handling

A major advantage of cameras with viewfinders is the ability to stabilize the camera body. To do this, hold the camera with both hands up to your eye, stand with your feet slightly apart, and press your elbows firmly against the sides of your ribcage. If you then breathe in and out slowly and briefly hold your breath when pressing the shutter button, the image will remain sharp even at longer shutter speeds.

Fig. 33: Proper posture while photographing to stabilize the camera.

Stabilization

Many lenses and some camera bodies feature image stabilization. This compensates for the involuntary movements you make while photographing. Stabilization helps with:

Long focal lengths (telephoto lenses),
Long shutter speeds.

Fig. 34: A shutter speed of 1/8 s handheld without a stabilized 100mm lens results in a blurry image.

Fig. 35: A shutter speed of 1/8 s handheld is possible with a stabilized 100mm lens.

Image stabilization cannot do anything against movements that a subject makes during the exposure.

When using the camera on a tripod, image stabilization should be turned off.

Continuous Shooting (Burst Mode)

Almost all cameras feature a setting where pressing the shutter button once captures images continuously until the button is released. This is called continuous shooting. It works until the camera’s internal buffer or the memory card is full. It is a useful feature when portraiting a group, allowing you to select the image later where hopefully everyone has their eyes open and isn’t looking awkward. However, you should keep in mind that you will have to review and select from all these images later, which can sometimes be annoying. People used to photograph differently in the past, since a maximum of 36 exposures fit onto a roll of film and every shot cost money. Continuous shooting is highly useful in wildlife and sports photography. Nevertheless, we at Tiger Graphics rarely use continuous shooting modes.

Fig. 36: Continuous burst of a young blue tit.

Fig. 37: Sometimes all the images in a series are…

Flashing with the Internal Flash

Most cameras offer at least two ways to work with the internal flash:

The flash illuminates the scenery. The shutter speed is kept very short by the camera. This results in a typical flash image that is sharp.
The flash acts only as a fill light. The shutter speed is hardly altered by the camera. In low ambient light, the exposure time remains quite long. This results in a balanced image, which, however, may be blurry.

Fig. 39: Shutter speed 1/250 s. This makes it highly likely that the subject will be sharp, but the flash effect is clearly visible.

Fig. 40: Shutter speed 1/10 s. Only works with a very steady hand and a stationary subject. In return, the flash provides only a tiny amount of fill light, and the image looks natural.

When taking flash photos of people or animals, do not flash directly into the eyes to avoid red eyes. Turn on the camera’s internal red-eye reduction if available.

On some cameras, the flash only works when photographing with the mechanical shutter.

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RAW or JPG?

If an image is perfectly captured, it doesn’t matter whether you store it as a RAW or a JPG file. But what constitutes a perfectly captured image? Sometimes you want to improve or stylize the photo afterward. In such cases, the RAW format (raw data format) is better suited. It contains all the image information provided by the sensor; nothing is compressed or discarded. However, if you want to share an image quickly, JPG is the better format because it is more universal and does not need to be “developed” in software first like a RAW file. There are further advantages and disadvantages listed below:

Advantages of JPG

JPG is widely supported
- Almost all apps and programs can handle JPGs.
JPG files are comparatively small
- The continuous shooting rate is higher and lasts longer, meaning many images can be captured in quick succession.

Disadvantages of JPG

Incorrect exposures are nearly impossible to rescue.
- An incorrect white balance cannot be fully corrected.
- Blown-out highlights and crushed shadows cannot be recovered.
Lossy compression; JPGs are compressed.

Advantages of RAW

Incorrect exposures can be rescued much better.
- White balance is completely adjustable.
- Blown-out highlights and crushed shadows can usually be saved.
No loss of information.

Disadvantages of RAW

A RAW image is a digital negative that must be “developed” using special software.
RAW is manufacturer- or camera-specific.
RAW files are very large:
- A lot of storage space is required.
- The continuous shooting rate is lower because a data block has to be written to the memory card.

Alongside RAW and JPG, other formats exist. In particular, the HEIF format is recently being used by some smartphones!

Preparation

Here are a few tips to help avoid frustration when going out on a photo tour:

Check the functionality of the cameras.
Check the lenses and clean them if necessary.
Check the battery charge level inside the camera.
Pack fully charged spare batteries.
Pack spare memory cards and film.
On cameras that offer the option, disable firing the shutter without a memory card. Nothing is more annoying than realizing after the session that the images were not saved.
Think about backup options when traveling, and perform backups daily if possible.
Don’t forget water, cookies, and a warm jacket.

Some cameras feature two memory card slots and can use one of the two as a backup. However, this does not help if the camera is lost or falls into the water. Therefore, it is better to set up a backup option outside of the camera body.

Image Editing

Subsequent image editing can be performed directly via the camera’s internal software on some models, or using photo software on a computer. Some camera manufacturers offer their own software. Extensive editing options are available via both free and commercial tools. If you work in RAW format, software to “develop” the raw data is absolutely mandatory.

Test or read up beforehand to verify whether the software supports the RAW format of your specific camera model.