Indexes on the camera body and lens must be aligned when removing/attaching a lens from a DSLR. On this camera, the red dots need to be aligned.
The viewfinder
Your view of the world through a DSLR is dominated by the viewfinder. Although what appears on the screen does vary a little from camera to camera, the image below shows the comprehensive information you can expect to see.
Viewfinder display
In the main viewing area of the diagram below, you can see the five AF (auto-focus) zones, shown as square brackets spread across the central portion of the screen. The memory card warning symbol illuminates if there is no card in the camera. The information in the black area covers a wide range of information, from aperture and shutter speed in use to the number of images remaining on the memory card. The viewfinder display varies slightly from camera to camera.
Across the bottom of the viewfinder in the black zone, from left to right, the following information is displayed:
1 Focus confirmation LED
2 AF area in use
3 Exposure lock
4 Flash needed warning/Flash status lock
5 Shutter speed
6 Aperture
7 Under-/overexposure and bracketing
8 Flash compensation
9 Auto-sensitivity indicator
10 Exposure compensation
11 Number of images/space (in kilobytes) left on memory card
12 Flash ready
Image and colour performance
Another key benefit of a DSLR – indeed, of almost all digital cameras, bar the most basic – is the control that you have over the way an image is treated by the camera’s computer.
Enhancing the image
All DSLRs allow you to alter and enhance the camera’s image processing of a specific scene or colour set-up. For example, Canon’s high-end professional DSLRs use a Colour Matrix set-up to help enhance colour by increasing or decreasing the saturation, and preset the colour performance for a type of subject, typically portraits, or for a specific colour space.
Preset modes
DSLRs aimed more at the consumer than the professional, such as the Sony Alpha 450, have other presets for both colour performance, such as Standard, Vivid, Sunset and Portrait, and for specific scenes. These Subject Program, or Scene, modes can set the camera for specific subjects as opposed to simply a type of colour performance.
Scene modes, such as Portrait, Landscape, Macro and Sports, allow you to set the camera quickly to get the most from the subject at hand, automatically setting the camera to its optimal settings (including shutter, aperture and metering) for the selected scene. These can be used in conjunction with the colour settings as well, if required.
In each case, the camera applies special processes to captured images and optimizes those attributes you’ve selected to enhance the image in the way that you’d like. In practice, unless you know from experience what these settings offer, you will need to do some experimenting since, for example, a vivid setting on one shot of flowers may look oddly artificial on a portrait picture.
DSLRs, such as this Sony A450, have powerful image performance enhancing settings built into them. These allow you to predefine the colour parameters and image processing attributes, as well as the camera’s physical settings (shutter speeds and/or apertures, for example), all in advance of taking a shot.
Exposure
The metering modes, exposure compensation and bracketing are some of the more powerful controls at your fingertips on a DSLR. Using them to fine-tune your images helps you to create shots that look exactly as you want them.
Metering modes
A DSLR can measure the light for a given scene in a variety of ways. It has a matrix of light sensors, or meters, that covers the area you see through the viewfinder to give a general light reading. Even though it has a large number of zones to measure light from, it can also do it using smaller, specific areas of the frame.
There are three main modes of metering: matrix (multi-zone or honeycomb), centre-weighted and spot metering. The first uses all the metering zones the camera has at its disposal (the number varies from model to model, and manufacturer to manufacturer) and measures an average of all the zones to give the ‘as metered’ exposure value.
The second, centre-weighted metering is, as the name suggests, where the light in only the central portion of the frame is measured. The third mode, spot metering, is where a small, central spot of the subject or scene is metered; in some cameras, you can adjust the size of the ‘spot’ yourself from, say, a 4 per cent (in area) ‘spot’ to an 8 per cent ‘spot’ in the centre of the frame.
The advantages of one method of metering over another depend on the subject being photographed but, broadly speaking, matrix metering works perfectly well for most shooting situations. Centre-weighted metering is ideal for complex lighting, or where there are areas of deep shade or light and you want to bias exposure to one or the other. Spot metering allows you to meter precisely from a small area, which makes it ideal for portraits or macro work, where it’s important to get the metering spot on, so to speak.
Professional tips
• Use the centre-weighted, or spot, mode when shooting portraits with strong backlighting.
• Auto bracketing is useful when you are having to work under pressure.
• With spot metering you can check the light in specific areas of your shot to ascertain the best exposure.
• Although digital cameras have a wide exposure latitude, there is nothing like getting the right exposure to begin with.
Exposure compensation
Exposure compensation is a method of fine-tuning the exposure of a scene by compensating for overly bright or dark areas. This is done by, typically, up to three stops of exposure, depending on the type of DSLR you have. Set using a specific control on the camera, exposure compensation can be applied to one image at a time, or until you reset the compensation feature back to its ‘as-metered’ exposure level, where there is no compensation.
This sequence of photographs shows how you can automatically bracket around the metered exposure for a shot to provide more choice later on, allowing you to see what has actually worked best for the image. The exposures shown (clockwise from above left) are: one stop underexposure, one stop overexposure and as metered.
Auto-bracketing
Automatic exposure bracketing can be thought of as an insurance policy for your snaps. It is similar to exposure compensation in that it changes the exposure to a predefined level and for the same reasons, but when an image is shot, the camera will automatically shoot one image (or more, depending on the camera) at the set amount of overexposure and one at the same set amount of underexposure. You’ll get three (or more depending on the camera) images, one of the correct ‘as-metered’ exposure, then one underexposed by, say, half a stop and one overexposed by the same amount, depending on what you’ve set the camera to do. Then you can decide later (on the camera screen or on the computer, for example) which is the best for the subject.
Using auto-focus (AF)
One of the key factors affecting the success of any shot is how sharply focused it is, even though you may sometimes want creative blur or an unfocused look. Whatever the shot, DSLRs have special focusing modes