Despite all the inbuilt technologies in today’s cameras, some key choices should be made before going on a photo shoot…
How well-prepared is your camera before you start to take pictures? Some important choices should be made to ensure you obtain the results you want.
Factors like the file format you use can play a key role, as can the drive mode setting, the metering mode, whether to shoot stills or movies (or both) and whether to take advantage of stabilisation (camera and/or lens) and built-in aids like face and eye detection or dynamic range adjustments
The effects of JPEG compression show up in challenging shooting situations. This photograph of a small-spotted genet was taken at night in the Witsand area in South Africa with a M4/3 camera using an ISO setting of 25,600 plus an exposure of 1/13 second at f/5.6 (the maximum aperture of the lens at the 140mm focal length).
The raw file captured simultaneously with the JPEG enabled more detail to be extracted and delivered better colour reproduction and a wider dynamic range in the image.
1. File Format
JPEG is considered the ‘universal’ file format because it can be viewed on any screen, output to any printer or device and stored quickly and easily because it automatically compresses the data to reduce the amount of storage space required. Shooting JPEGs is best when you just want to post images on sharing websites, or view them on TV sets and monitor screens.
Because it can be displayed on any device, JPEG is the format of choice for images that are required quickly, such as those sent to publishers or submitted for competitions. It is supported by all image editors and commercial printing equipment. Most cameras provide several settings covering the image size (in pixels) and quality (level of compression) for JPEGs recorded in the camera. The same is true when you save JPEGs via an image editor.
Unfortunately, each time a JPEG image is saved, it will be compressed, which means the more often a JPEG file is saved, the more data is lost. After several re-savings, the quality of the image will have deteriorated noticeably. So most photographers find it’s useful to have an uncompressed file containing all the image data recorded when the shot was captured as well, if only for archiving.
Two options are available: TIFF and the camera’s native raw format. The former is editable, while raw files need to be converted into editable formats. Raw files (often shown as ‘RAW’, although the term is not an acronym) record raw data captured by the camera. This information passes straight to the memory card without the camera’s microprocessor adjusting it.
Most cameras save the data in a proprietary format determined by the camera manufacturer, which requires compatible conversion software (some of questionable functionality). This can be inconvenient for photographers who want results in a rush
While most enthusiasts’ cameras support both JPEG and raw capture, few provide TIFF as a native capture option, because they are usually huge and take a long time to process. Raw files can be converted into 16-bit TIFFs to obtain the maximum amount of image data for editing.
Files saved in TIFF format can be uncompressed or losslessly compressed, both options retaining all (or most) of the original data. Edited TIFF files are easily converted into 8-bit JPEG format where they will retain the advantages of having been edited in the higher bit depth format (as shown in the illustration below) but be easy to view, share and print.
Professional photographers and serious enthusiasts usually capture still images as raw files, which are either uncompressed or compressed losslessly to retain all the image data. This allows the photographer to adjust sharpness, contrast, brightness range, colour balance, saturation and other parameters without compromising picture quality.
The workspace for a popular conversion software, Adobe Camera Raw, shows the adjustments that can be made while processing raw files. Raw files can also be saved in TIFF format with a 16-bit depth, which retains all the image data and provides additional scope for tweaking the file.
When speed is an important criterion, many photographers elect to shoot only JPEGs. If you’re working to a deadline, shooting to output for online viewing or printing in a newspaper, shooting JPEGs makes more sense. A slight loss of image data is largely irrelevant in all these situations and JPEGs can be sent via Wi-Fi directly from the camera to a smart device for transmitting to a central office or posting in a blog.
Where speed is irrelevant, raw files are preferable as they provide the maximum amount of image data to work with when editing shots. All raw-capable cameras let you capture raw and JPEG files simultaneously via a RAW+JPEG setting and some provide adjustments to the size and quality of the JPEG shots, a handy feature where storage space is limited.
Shooting raw files involves a few caveats. Raw files are larger than JPEGs and, even though the latest cameras can record bursts of raw files almost as fast as JPEGs, the buffer memory for storing them temporarily can’t hold as many files. Entry-level cameras usually run out of space after fewer than 10 raw files are recorded, and users must often wait for 30 seconds or more until the memory is cleared and the camera is able to capture more shots.
Professional sports photographers often record images in JPEG format, particularly when they know they will have to use the continuous shooting mode and when the images are destined for newspapers or websites.
2. Drive mode choice
While it’s easy to be seduced by claims of fast continuous shooting rates, continuous shooting has positive and negative aspects. Unless you want to capture a sequence of shots covering a specific action, most cameras will deliver a higher percentage of sharp shots with the single-frame mode, particularly when subjects are moving.
When the direction of movement is predictable and you can shoot from a fixed position, frame rates slower than five frames/second can provide good coverage of action.
Avoid the burst mode if the action peaks in a split second, such as at the top of a jump or dive or the finish of a race. Unless the camera supports speeds faster than 10 frames/second (fps), there’s seldom enough time for the camera to ‘find’ the subject and you’ll only get near misses.
Even when cameras support continuous shooting faster than 10 frames/second, it can be difficult to track subjects like birds in flight and you need fast and accurate tracking AF to obtain sharp images for the entire sequence.
Try to keep bursts short to ensure the images move quickly to the memory card, freeing the camera to shoot again. In many cases, the action can be encompassed within three to five frames, letting you pause a second then shoot another burst.
Check your camera’s instruction manual to find its limitations. Many cameras lock the focus on the first shot in a burst. Where continuous AF is supported, capture rates are often slower, sometimes substantially so. Many burst modes can’t be used in conjunction with flash and zoom and some require shutter speeds of 1/30 second or faster.
3. Metering
Selecting the optimal metering pattern for the subject enables the camera to evaluate the brightness level(s) and adjust aperture and/or shutter speed settings correctly, depending on the exposure mode you have selected.
Most cameras provide three metering options: multi-pattern evaluative (or matrix), centre-weighted average, and spot. Multi-pattern metering divides the subject area into multiple segments and individually evaluates the light level within each, usually biasing the overall exposure to counteract differences in brightness within each segment and between adjacent segments. Some cameras also include distance information from the autofocus system and/or colour data. Multi-pattern systems are good all-rounders that work with most types of scenes, including backlit subjects.
Centre-weighted average metering produced a well-balanced exposure in this shot, which was taken with a 105mm lens on a ‘full frame’ DSLR camera.
Centre-weighted average metering integrates readings from all over the frame, placing more emphasis on the centre area. It’s effective for subjects with an average brightness range where the main area of interest is central and can often be a good choice for action shots.
Spot metering takes a single reading from a small area in the field of view. The size of the spot is normally expressed as a percentage of the field of view, with typical spot sizes ranging from 1% to about 4%. So-called partial metering systems have slightly larger metering areas but work on the same principle.
Spot metering on the rider’s face delivered a correct exposure for the main subjects in this scene, in which the wide brightness range exceeds the sensor’s recording capabilities. Note the blown-out highlights in the sky and the near-black shadows.
Spot metering is ideal for backlit subjects and any other subject where there’s a large difference in brightness between the subject and the background. If the camera has focus tracking, it’s also good for subjects that are in motion. Simply centre the spot on the area you want to measure and press the AE lock button, then press the shutter release half way down. This locks the exposure (and focus), allowing you to re-compose and take the shot by pressing the shutter all the way down.
4. Stills or video?
With many new cameras recording 4K video clips, photographers have gained a new method for capturing fleeting moments. The maximum frame resolution for 4K video is 4096 x 2160 pixels, although most cameras provide the ‘consumer’ 4K resolution of 3840 x 2160 pixels. Either way, a 4K video clip is equivalent to between 8.3 and 8.8 megapixels. Each frame is printable at A3 size (420 mm on the long axis), which meets most amateur photographers’ needs. Some cameras provide special 4K Photo modes for grabbing printable JPEG frames from movie clips.
4K movie recording is a great way to capture fleeting moments since you can pick out single 8-megapixel frames like the one shown here from a recorded movie clip.
The main advantage of shooting motion in 4K video is relatively high frame rates; typically 24 frames/second. This is much higher than most still cameras support and should provide enough sharp frames to cover several ‘decisive moments’. However, 4K video requires the use of fast, high-capacity memory cards, which are expensive but reduce the risk of running out of memory.
5. Stabilisation
Although seldom necessary with wide angle lenses, when shooting with telephoto lenses, stabilisation can make the difference between a usable image and a dud. The risk of shots becoming blurred due to camera shake increases in proportion to the zoom magnification. You can prevent most camera shake by mounting the camera on a tripod. However, this may not be convenient because it limits the photographer’s manoeuvrability.
Without effective stabilisation, this hand-held shot of one of the Zig Zag Railway engines at night would have been impossible as it required a 1/8 second shutter speed with ISO 1600.
Stabilisation can be important for hand-held shooting, particularly in low light. It doesn’t matter whether it’s in the camera body or in the lens; both will be useful. In-camera sensor-shift systems work with any lens you attach to the camera, even wide-angle lenses. The latest cameras with this technology offer shake compensation in excess of 3.5 f-stops.
Many cameras with sensor-shift stabilisation offer several stabilisation modes to counteract vertical, horizontal and back/forth shaking. Some of these modes are available on high-end stabilised lenses. Stabilised lenses are usually larger, heavier and more expensive than lenses without built-in stabilisation because they contain more components.
6. Face detection/recognition technologies
Most imaging devices today include face detection technology, usually as part of their autofocusing systems. Many cameras can also be programmed to recognise individual faces in images.
These technologies identify and focus on human faces and some can ‘recognise’ pets. Many let you program them to identify specified individuals. Professional sports photographers use them for getting sharply-focused photographs for clients. Family photographers will also find them useful for keeping focused on the ‘star’ in a scene.
Face recognition technology makes it easy to obtain sharp images of people against potentially distracting backgrounds.
Deciding which of these settings to use will depend on the kinds of pictures you plan to take and how they will be shared. If in doubt, opt for settings that give you the best chances of recording as much image data as possible and ensuring your pictures will be sharp.
The more data you capture, the easier the image will be to work with and the better your archived shots will be if you need to access them again. It’s easy to downscale images for different applications; upscaling low-resolution shots is usually problematic.
Article by Margaret Brown – see Margaret’s photography pocket guides
