Camera Buying Guide

Exposure

Understanding Shutter Speed, ISO and Aperture

The amount of light a camera’s sensor captures is defined as the exposure. Too much light produces a washed out (overexposed) photograph while too little light results in a dark (underexposed) photo.

A camera’s exposure is directly affected by its aperture, shutter speed and ISO settings. However, these settings also allow you to control how each photo will look. Typically, there are three main settings that can allow you to explore different effects and styles:

• Shutter speed determines the duration of exposure. In simpler terms, it determines the duration that the aperture stays open for.
• Aperture is the opening through which light travels in the camera. Thus, you can control the aperture opening to alter the amount of light entering your camera. Naturally, a larger opening will allow more light to pass through.
• ISO determines your camera’s sensitivity to light. A higher ISO implies that your camera has a higher sensitivity to light.

Let's look at how the aforementioned factors affect the image captured in detail-

Shutter Speed

The shutter speed setting allows you to control how long the shutter stays open for, allowing light to pass through the aperture and reach the image sensor. Shutter Speed is measured in seconds and fractions of seconds like 1s, 1/2s, 1/4s, 1/250s, 1/ 500s, etc.

How does it help?

A high shutter speed allows you to click moving subjects, freezing a moment of action in the photographs. For example, a photo of kids dancing in the rain or a photograph of moving trains.

Different Shutter Speeds

High Shutter Speed

• A faster shutter speed, like 1/2000s, will freeze the action of the object and avoid unnecessary blur effect in the image
• This shutter speed is ideal for sports, action and wildlife photography

Slow Shutter Speed

• A slower shutter speed, like 1/4s, will click the subject’s movements and cause blurring of the image
• Ideal for capturing images of streams and waterfalls

Aperture and Depth of Field

Aperture is the opening of the lens that allows light into the camera. The amount of light entering and passing through the camera can be easily controlled by changing the aperture size. Typical examples of aperture ranges are f/1.6, f6.3, f/10, f/22.

The measurement of the aperture is stated as the f-stop or f-number. A higher f-stop number (F/22), indicates a smaller aperture opening which means that less light can pass through the lens. In such cases, the object and background, both turn out to be sharp. This is called ‘a larger depth of field’ as both the object and background are in focus. Alternatively, a lower f-stop (F/1.8) indicates a larger aperture and more light passing through the lens. This gives a shallow depth of field with a sharp object and a blurred background.

Types of Lenses

 

ISO

ISO Sensitivity determines how sensitive the camera’s sensor is to incoming light.

For example, if you're shooting indoors with low light conditions, you require a higher ISO setting. Similarly, if you are shooting outdoors, in bright lighting conditions, you require a lower ISO setting. Typically, DSLRs come with an ISO ranging from 100 to 51,200, allowing you to control your ISO sensitivity manually.

Exposure Control

Considering that photography is all about light, exposure control is an important thing to know. You can achieve the same exposure through different combinations of ISO, aperture and shutter speed. Controlling the exposure can help you bring about interesting light effects in your photograph. The most popular effects that are easy to execute are bokeh, motion blur and glow.

A combination of high ISO setting, larger aperture and a slow shutter speed will allow the camera to capture more light, resulting in a brighter image and vice versa.

BURST MODE

Burst mode allows you to take a number of photographs in succession by holding the shutter button down. Burst mode is measured in frames per second, that is, the number of pictures that can be captured in one second. Some DSLRs allow you to take as many as 10 shots per second, or more. Burst Shots can be taken in lesser FPS too.

SENSOR TYPES

A sensor is found in digital cameras for converting light into electronic signals that create an image. Bigger sensors capture photographs that have a better and higher quality. There are mainly three types of image sensors used in cameras.

CCD
(Charge Coupled Device)

CCD sensors provide superior image quality with better dynamic range and noise control. They consume a lot of power. Not a lot of cameras have CCD sensors.

CMOS
(Complementary Metal-Oxide-Semiconductor)

Usually, cameras with CMOS sensors are cheaper than the ones with CCD sensors. They consume lesser power. Panasonic, Olympus and Leica use a different type of CMOS sensor technology which is called the MOS sensor or NMOS sensor. This sensor can produce CCD-like image quality with lower energy consumption.

BSI CMOS
Back Illuminated CMOS

These are more advanced CMOS sensors that employ a different layout. They produce photographs with less noise and better color reproduction compared to CMOS sensors. Their performance in low-light is noteworthy.

SENSOR SIZES

Full-frame and Cropped Sensors

Sensor sizes are usually compared to a standard 35 mm film. A standard 35 mm frame or a full frame is 36 mm x 24 mm. There are two types of sensors:

• Full-frame Sensors
• Cropped Sensors

What is Crop Factor?

Most cameras come with sensors that are smaller than the 35 mm film format. So, any image you capture with these cameras is created from a smaller area than the standard film, which is why they are called cropped sensors. The smaller sensor will capture a smaller field of view when the same lens is used on two different-sized sensors.

The crop factor determines how exactly the field of view changes in cropped sensors when compared to full frame sensors.

For example - APS-C sensor has a crop factor of about 1.5x to 1.6x. A 50 mm lens on this sensor would give the same field of view as a 75 mm lens on a full-frame sensor.

Which Sensor is Ideal? Full Frame or Cropped?

Advantages of Full-frame Sensors

• Broader dynamic range, better sharpness and better low-light performance
• Preferred for architectural photography as full-frame sensors can capture a wider angle with tilt-shift lenses

Advantages of Cropped Sensors

• Cheaper and lighter in comparison to full-frame sensors
• They are also better for shooting faraway objects due to the extra reach that can be achieved from the crop factor
• Very useful for shooting sports and wildlife

Sensor Size Comparison:

Resolution

The resolution of a photograph is measured in terms of the number of pixels it contains. Camera Resolution is given in Megapixels (MPs) where 1MP means 1 million pixels.

Advantages of High Resolution

A higher resolution photograph can be achieved with a camera of a higher MP rating, which means:

• More detail and less grainy shots
• Better print quality for larger prints
• Reducing the chance of noise in the image

Video Quality

Most cameras are capable of capturing Full HD videos that display highly detailed images with bright colors. Some cameras also come with special autofocus technology for videos which allows you to capture moving subjects in focus. Newer Mirrorless and DSLR cameras can also record videos in 4K (3840 x 2160), also called ultra high definition.

Features

Wi-fi

Built-in Wi-Fi enables you to easily connect to a smartphone or tablet and upload photos. You can also share pictures, through social networks, directly from the camera.

GPS

Some cameras come with GPS features that track the specific location of each photograph, allowing you to create a visual map.

NFC

The NFC (Near Field Communication) feature offers the added advantage of one-touch wireless connectivity with compatible smartphones and tablets. A connection is built automatically when the mobile device touches the DSLR, allowing for immediate transfer of images or videos between devices.

Built-in HDR

The built-in HDR function in a DSLR camera allows you to take a number of pictures from each scene you select, all at different exposures. The camera will then combine the best parts of each photograph into one great image which produces a higher dynamic range.

Autofocus Points

Focus points are the small empty squares or dot that you see when you look through your viewfinder. The number of autofocus points depends on the camera, and can range from a very basic system of 7 points on an entry level DSLR, to a highly complex system of 61 points on a professional camera. Type of Auto Focus-

• Contrast Detect - It is most accurate but slower in acquiring Focus.
• Phase detect - It is less accurate than Contrast detect mechanism but faster in acquiring Focus.

Most Cameras implement either of these two types, however, there are many cameras which utilize both types.