Camera - definition

Glossary

Provides the ability for a phone to capture still images and video. Modern smartphones come with both a primary camera that is rear facing and a secondary camera that is front facing for self portraits (selfies), video calling and biometric face identification.

The majority of today’s smart phones come equipped with a very comprehensive set of camera related specifications. What was once a nice to have feature has now become as equally important as other smart phone features. For many people their smart phone has become their main camera as it’s the one the always have on them, resulting in a decline in sales for dedicated digital cameras.

Smart phone photography is all about collecting photons (light) and converting them to electrons (image). How you capture and process is key to producing high quality images of your subject.

Resolution

Measured in megapixels, a higher megapixel count doesn’t always equate to a better picture. The desire to have more and more megapixels has slowed as manufacturers focus on the quality of those megapixels captured. This is accomplished by having larger pixels within the CMOS Sensor in order to capture more light, a higher resolution CMOS sensor will have smaller pixels and therefor capture less light. However, higher megapixels facilitate ‘cropping’ of the original without losing too much detail. Higher megapixel images also ensure a higher quality image when printed, for example when printing ‘posters’.

As a comparison, when playing back images on a Television, a 4K TV has a 8.3 megapixel count whilst a HD TV has a megapixel count of 2.1.

Aperture

Aperture Chart indicating how the f-stop number relates to amount of light captured

The Aperture of a lens indicates how much light the lens lets in. The larger the aperture the more light is let in whilst a smaller aperture lets in less light. Measured in f-stops, oddly as shown in the aperture chart above, the larger the aperture the smaller the f-stop number. An aperture of f/1.4 lets in more light than a aperture of f/8.

Shutter Speed

Due to the tight constraints within a smart phone, a electronic shutter is utilized as opposed to a mechanical one to expose your photo’s.

Sensitivity

Known as ISO, it’s the level of sensitivity that the smart phone camera sensor has to light. On a sunny day the sensor doesn’t need to be that sensitive as large amount of light is available for the sensor. Conversely, in low light conditions the sensitivity has to be increased to capture the limited light available - this ‘boosted’ level of sensitivity though can lead to noise and grain in your shots. The lower the ISO number the better as the sensor can produce the best image quality without adding noise to the picture.

Lens Focus Type

Most modern smart phones have an internal auto focus system, you can’t see this as the external Lens Covers is fixed in place. Only auto focus cameras can allow shooting of really close objects - i.e. macro shooting.

The majority of smart phones, when zooming in on your subject, use a digital zoom which produces a lower quality image at any given size as it’s effectively ‘cropping’ in for you. However, some of the new flagship smart phones are using a 2nd lens to provide Optical Zoom.

Optical Image Stabilization (OIS)

Helps eliminate camera shake and produce a better quality image. Some phones successfully use Digital OIS but the best phones use a mechanical Optical Image Stabilization system.

Flash Type

A flash will brighten your subject when lighting conditions are poor.

LED flash technology was until recently the most common flash for smart phones. It’s low power, takes up little physical space and can be used continuously. However, it only illuminates a very small area, it’s slow (resulting in blurred fast moving objects) and the color temperature is often badly suited for a given scene.

For example, an LED flash gives off light roughly at a temperature of 5,500 kelvin (K) which equates to the temperature of Sunlight. This is why some photo’s may appear blue when shooting indoors in low light with an LED flash.

In order to provide a light temperature that better matches the environment some smart phones include multiple LED’s in the flash itself. Each LED produces a different temperature of light, and when combined can produce a more natural looking image.

Image Signal Processor (ISP)

An equally important part of the smart phone camera experience is the Image Signal Processor (ISP), this is part of the silicon within a smart phones chip-set/CPU and in conjunction with the phones software and OS provides additional enhancements and special effects when both capturing images and to the images once captured. These include face detection, filters, panoramic scene capturing and object identification.

Images are also geo-tagged with the GPS co-ordinates of where the image was captured if the phone has an internal GPS chipset.

Video

All the above elements come also come into play when capturing video. Most modern smart phones are capable of capturing 720p HD video 30 frames per second (FPS). The greater the FPS the smoother the video or in the case of slow motion shooting, the slower you can make a video without losing quality. The higher the resolution and the greater the number of frames the more storage space is required.

Common Video formats & frame rates are:

  • 1080p HD at 30 fps
  • 1080p HD at 60 fps
  • 4K at 24 fps
  • 4K at 30 fps
  • 4K at 60 fps

Slo-mo

  • 720p HD at 240 fps
  • 1080p HD at 120 fps
  • 1080p HD at 240 fps

Formats and storage

In most cases still images are stored either as jpeg or HEVC, these compress the image file size without losing any detail (loss-less compression). Some high end phones allow the RAW image file to be used but these are much larger in size. The most common format for recording video is H.264. Google and Apple provide paid ‘cloud’ storage for off-loading your photo’s and video’s over WiFi or cellular to reduce the impact on the phones internal storage.