Used Digital Camera Buying Guide

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Used Digital Camera Buying Guide

Not everyone is able to spend large amounts of money on brand new digital cameras, but thanks to the used digital camera market, there are many different types of used digital cameras to suit practically any budget. Digital cameras begin with the cheaper digital point-and-clicks and compacts, and end with bridge cameras and digital SLRs (DSLRs). No matter which type of camera is purchased, the most important thing is to understand which features have the greatest bearing on image quality, image dynamic, user functionality, and flexibility.

Digital Camera Basics

Digital cameras operate with mechanisms that are very similar to classic analogue cameras, though the key difference is that a digital camera captures images onto a photosensitive plate known as an image sensor, whereas an analogue camera uses a film. Almost every modern digital camera includes a lens, aperture, shutter, and flash, and more expensive models will come with viewfinders and optical zooms.

Lens, Aperture, and Shutter

The lens bends and focuses the light as it enters the camera. The Aperture is the hole in the lens which the light travels through when a picture is taken, and this hole (which can be set to different sizes by the user) regulates the amount of light that passes through the lens. The camera shutter lies in-front of the digital camera sensor. When a photo is taken, the shutter opens, allowing the camera sensor to be exposed to the incoming light, and after a certain length of time - which depends on the camera's specifications and the shutter speed set by the user – the shutter then closes, preventing any further light from striking the sensor.

Viewfinders and Digital Effects

Different types of digital camera come with different optical viewfinder mechanisms, while some come with an electronic viewfinder only. For compact digital cameras with optical viewfinders, the light that comes through the viewfinder is not the same as the light that creates the image (mirrorless lens), which means that that the image obtained might not be as expected. Digital SLR cameras avoid this problem with a direct mirror lens viewfinder mechanism.
Automatic image control and inbuilt digital effects are very popular features with modern digital cameras. They can be used to ensure good-quality images without difficulty or the trouble of manual control (such as auto-flash and environmental auto-sets), and for creative and artistic shots (such as sepia, negative, fragmentation, illustration effects, and watercolour effects).

Digital Camera Quality

The three most important aspects that govern the quality of the images of any digital camera are the aperture size, ISO, and shutter speed. Other aspects such as lens and sensor size are also important – lenses are important for cameras in the middle/high range, and the angle of the lens describes the maximum width of the picture.

Aperture Size and Focal Range

The aperture is so important because it governs the depth of field, which in turn, governs the clarity and crispness of the image depending on whether the subject of the image is close-up or far away.
Larger maximum aperture sizes equate to more throughput of light, which means better performance in low light conditions and better shots for small, close-up objects and artistic shots with crisp foregrounds and blurry backgrounds. Smaller apertures are useful for panoramic landscape shots where everything needs to be in focus. While all cameras can handle distance shots where everything is in focus, not all cameras have a large enough aperture setting to handle close-up shots with good results.
For digital cameras, aperture size is given by the focal length 'f' divided by the maximum available aperture, for example f/1.8, f/5.6 and f/16. Most digital cameras have a minimum available aperture of f/16 or f/22, but only the better digital cameras will have a maximum available aperture below f/4. Remember that a smaller divisor means a bigger aperture.


ISO is a measure of how sensitive the digital camera sensor is to light. A lower ISO number means lower sensitivity to light, which increases the image quality and reduces the amount of grain in the picture. A common trick that cheaper digital camera manufacturers use is to boast high pixel numbers, but hide a high ISO rating, which leaves buyers surprised when images turn out noisy and grainy.
When looking at used digital cameras, check for the Base ISO rating, which is the lowest sensitivity (and highest image quality) the camera can produce. Low sensitivity is not always good for low light environments without using a flash, and this is what makes larger sensors advantageous, as they perform better in low lighting for a given ISO. Like the depth of field, the ISO can be changed to suit the purpose.
Base ISOs in the current digital camera market range from ISO 100 to ISO 3200, with each incremental ISO a doubling of the previous (i.e. ISO 200 is twice as sensitive as ISO 100, and half as sensitive as ISO 400).
The sensitivity of the camera sensor has a very big impact on the overall price of the digital camera; it is often a good idea to sacrifice other aspects of a digital camera to gain a digital camera with a low ISO.

Shutter Speed

A slower shutter speed means a longer exposure time, which causes motion blur when objects are moving, while faster shutter speeds mean the opposite, and if quick enough, can capture fast moving objects with high levels of clarity. Slower shutter speeds are also important for increasing exposure in low light conditions. Shutter speeds are responsible for much of the artistry and dynamism in photos, and a wider range of shutter speeds means better results in a wider range of conditions.


The number of pixels that a digital camera stores for each image is given by the resolution. Higher resolution in some sense means better image quality, but unless there is a need to print gargantuan pictures, resolution is not an important factor when choosing a digital camera. For cameras of a similar price, do not opt for a higher-resolution digital camera at the expense of the above factors, and in-fact, if the resolution is too high for the size of the sensor, higher resolution often means worse photos.

Digital Camera Comparison Table

There are three major types of digital camera in the market: Compacts, bridges and SLRs, from low to high in order of quality and price.

Type of Camera




Compact Digital

Highly portable, lightweight, and cheap. Automatic settings for convenience.

Screen viewfinder only. Limited to smaller apertures, higher ISOs and limited shutter settings and zoom.

Look for optical zooms, removable lenses and exposure settings.

Bridge Digital

Portable with good zoom range. Less expensive than DLSR.

Lens cannot be removed.

The middle ground between compacts and DLSRs. Suited for photography beginners.


The lowest ISO, widest aperture and advanced shutter settings, plus a range of extra features for full control.

Heavy, less portable, most expensive.

Best for advanced users and professional learners. Photography accessories.


Digital cameras are a wonderful way to capture events and to record memories, and with a rich selection of used cameras available there are options that will suit everyone, from general users with tight budgets to aspiring professionals. It is useful to remember that expensive DLSR cameras hold their value very well – this means buying used won't provide massive savings, but will make a good financial decision in the long run.

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