A Guide to Digital SLRs

If photography is a hobby of yours, you're a professional photographer or you're just interested in taking better photos, then a DSLR (Digital Single Lens Reflex) camera is the one for you. DSLR cameras let you take control. You can adjust a number of manual settings allowing you to photograph a diverse range of subjects and locations.

DSLR cameras have removable lenses, so you can interchange lenses to suit your needs. Also you see exactly what the lens sees. DSLR's have higher resolution sensors, quick response times, quick and accurate auto focus systems and the ability to take a large burst of pictures in only a few seconds. They contain bigger sensors that can capture more detail, creating a sharper image. The main advantage a DSLR has over the smaller compact digital cameras is the size of the lens - the much smaller lenses on compact cameras will never give you the same results as the larger DSLR lenses.

DSLR cameras can be bulky and weigh far more than Compact Digital Cameras. It probably is not the camera to take on a night out for example.

Here is a quick guide to some key features found in DSLRs:

The Lens

All DSLR cameras use interchangeable lens allowing to shoot everything from close up macro photography to long distance telephoto photography. Many DSLR cameras come kitted with a single or twin lenses. These are perfect for someone new to the world of DSLR.

The lens is 'mounted' on to the DSLR camera body. The point of connection between the lens and the body is called the lens mount. Lens mounts differ between manufacturers - Canon is different from Nikon which is again different from Pentax and so on. Each DSLR will only support a particular lens mount. Some DSLRs will not support older lenses used with 35mm SLR cameras. So it is a good idea to check out what lens mount the DSLR you're interested in has.

Generally lenses are not interchangeable between cameras from different manufacturers but are interchangeable between different models from the same manufacturer. There are also lenses available from third party lens manufacturers like Tamron and Sigma but you need to make sure the mount matches your DSLR.

At ASK we have a huge range of camera manufacturer's own DSLR lenses as well as third party DSLR lenses.

Below is a list of lenses and mounts we stock:

Live View LCD

Live View is a feature on DSLR cameras that allows you to frame and centre the shot you are about to take on the camera's LCD screen.

One of the main features' that sets apart DSLR from compact digital cameras is the ability to frame the picture exactly as that seen by the lens. On a compact digital camera you can compose the shot by just looking at the LCD screen. On most DSLR's, until recently, you had to use the viewfinder to compose the shot as you could not use the LCD screen. Many of the newer DSLR's allow you to use the viewfinder as well the LCD screen to compose the shots - this is called the Live View LCD.

AF (Autofocus)

Unlike many Digital Compact Cameras, DSLRs allow for manual focus as well as automatic focus. Plus DSLR Autofocus systems are far more accurate than their compact counterparts.

Camera manufacturers will refer to the number of 'Focus Points' or the DSLRs 'Area Mode'. DSLR autofocus systems come with a wide variety of Focus Points. Focus Points allows the camera to automatically focus on a target that is not in the centre of your frame. The higher the amount of focus points, the greater the amount of positions in the frame that the camera can focus on. Area Modes are presets that adjust the focus for a specific situation, for example group photos.

• If you are planning to photograph mainly static objects, you will not require a high number of focus points
• If you're photographing objects that move a lot, you will benefit from a high number of focus points

Most cameras may have two or three types of focus systems. The names and how they work may vary based on the camera manufacturer.

Metering Mode

Every DSLR contains a light meter to measure the amount of light entering the lens and sets the proper aperture to give the correct exposure when taking a photo. On some DSLRs you can select from a range of 'Metering Modes,' to suit the setting for photos you plan to take. This will automatically adjust the size of the aperture and shutter speed to improve the quality of your photo.

There are generally three separate metering modes. Although their names may vary between manufacturers, the purpose will be roughly the same:

• Evaluative (or Matrix, Honeycomb, ESP, Segment) - Divides the frame into a number of segments. The number of segments varies between different models and manufacturer. The camera then reads the light value from each of these segments and averages them out to obtain the best overall exposure.
• Partial (or Spot) - Only measures a specific area in the very centre of your image and sets the exposure for that area. On some cameras you can set the meter to read from any of the auto-focus points. This is best used when working in difficult lighting situations.
• Centre-Weighted Average - measures light in the more critical central area of the image and works well where there is even range of light values in the scene.

Dust Removal

The option to remove the lens from your DSLR means that the CCD digital sensor can get exposed to the elements. Dust particles may find their way on to the CCD sensor and these will show up on the photos.

To help remove unwanted dust and reduce the possibility of dust forming, a large number of DSLRs come with Dust Removal systems built in. Each camera manufacturer has a different name for their Dust Removal system, but each does the same job - repel or remove dust attached to the sensor.