Quality control for action photography

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.

1. File format choice

Most photographs are taken using the JPEG format, which automatically compresses the data to reduce the amount of storage space required. JPEG has long been seen as the ‘universal’ file format because it can be viewed on any screen, output to any printer or device and stored quickly and easily.

Shots that will be posted on sharing websites, sent to publishers or submitted for competitions should normally be sent in JPEG format. Camera users can normally select 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. However, each time a JPEG image is saved, it is compressed, which means the more often a JPEG file is saved, the more data is lost. Most photographers find it’s useful to have an uncompressed file containing all the image data recorded when the shot was captured as well. Files saved in TIFF format can be uncompressed or losslessly compressed, both options retaining most (if not all) of the original data.

But TIFF files can be very large and take a long time to process. So few cameras provide the TIFF format as a capture option.

The effects of JPEG compression show up in challenging shooting situations. This photograph of a leopard killing a porcupine required an ISO setting of 25600 plus an exposure of 1/15 second at f/5.6 (the maximum aperture of the lens).

A raw file captured simultaneously with the JPEG enabled more detail to be extracted in the form of improved colour reproduction and a wider dynamic range in the image.

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.

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. Unfortunately, most cameras save the data in a proprietary format determined by the camera manufacturer, which requires compatible conversion software. This can be inconvenient for photographers who want result in a rush.

When speed is an important criterion, many professional sports 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. Slight loss of image data is largely irrelevant in all these situations and most clients will prefer working with JPEGs directly from the camera, which can be transmitted by Wi-Fi to a smart device for sending on to a central office.

If you plan to edit your images after the event, however, it is generally best to shoot raw files each time you go on an action shoot. All raw-capable cameras provide the option to capture raw and JPEG files simultaneously via a RAW+JPEG setting. Some let you choose the size and quality of the JPEG shots, a handy feature where storage space is limited.

Raw files are much larger than JPEGs and, even though the latest cameras can often record bursts of raw files almost as fast as JPEGs, the buffer memory space available for storing them temporarily can’t hold nearly 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 becomes free and the camera is able to capture more shots.

2. Drive mode choice

It’s easy to be seduced by claims of fast continuous shooting rates but, as mentioned in Chapter 1, continuous shooting has positive and negative aspects. Unless you want to capture a sequence of shots covering a specific action (a golf swing, jumping a hurdle or an arabesque in ballet), you’re more likely to obtain sharper shots with the single-frame mode.

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 actions, as illustrated above.

Unless the camera supports speeds faster than 10 frames/second (fps), there’s often insufficient time for the camera to ‘find’ the shot and you’ll only get near misses. Avoid the burst mode if the action peaks in a split second, such as at the top of a jump or dive, the finish of a race or a dancer’s full extension.

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.

Keep bursts short to ensure the images move quickly to the memory card freeing the camera to shoot again. Transfers can take up to 30 seconds with some high-resolution cameras. 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. Some burst modes can’t be used in conjunction with flash and zoom and some require shutter speeds of 1/30 second or faster.

3. Stills or video?

With many new cameras recording 4K video clips, photographers have gained a new method for photographing action. Offering a maximum frame resolution of 4096 x 2160 pixels, a 4K video clip is equivalent to just over 8.2 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.

The main advantage of shooting action 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’. In addition, 4K video requires the use of fast, high-capacity memory cards so the risk of running out of memory is substantially less.

Stabilisation is vital when you’re shooting fast action with long telephoto lenses hand-held. This shot required a 300mm focal length. It doesn’t matter whether it’s built into the camera or the lens; both work equally well.

This sequence of movie frames shows how frame rates of 24 frames/second (or faster) can record the subtleties of an action sequence.

4. Stabilisation

When shooting with telephoto lenses, 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 manoeuvrability.

Without effective stabilisation, this hand-held shot of a brown hyena hunting at dusk would have been impossible. 300mm focal length on a M4/3 sensor (=600mm in 35mm format) with 1/60 second exposure at f/6.7, ISO 1600.

For shooting with the camera hand-held, stabilisation is valuable with long lenses, particularly in dim lighting. It doesn’t matter whether the technology is in the camera body or in the lens; both are almost equally effective.

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. Stabilised lenses are usually larger, heavier and more expensive than lenses without built-in stabilisation because they contain more components.

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.

5. Metering

It’s important to get the correct exposure levels when taking action shots and that usually depends on selecting the optimal metering pattern. The camera’s exposure meter will then evaluate the brightness level(s) and adjust aperture and/or shutter speed settings, 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.

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.

Partial metering on the subject’s face provided a well-balanced exposure in this shot taken with an 800mm lens on a ‘full frame’ DSLR camera.

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. 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.

6. Face detection/recognition technologies

Most imaging devices today include some kind of face detection technology, usually as part of their autofocusing systems. Many cameras can be programmed to recognise individual faces in images.

These technologies can be used to direct focus to human faces and even particular individuals. Professional sports photographers often use them to quickly lock focus on selected individuals and increase their chances for getting sharply-focused photographs for clients.

Excerpt from  Action Photography