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Latency is the time required to write the image you've just taken to your storage media. When you take a picture with a film camera, the shutter releases, and the image is immediately registered on the film at the speed of light, so to speak. When you take a picture with a digital camera, the image has to be captured and then recorded onto your memory card. The image capture and storage process can take a second or two — or even longer. How long the process takes and whether your camera will continue taking additional photos while writing to the card are important questions.
 | Some digital cameras use buffers (built-in memory) to temporarily let you keep shooting while the buffer contents write to removable memory. If you keep shooting, eventually the buffer fills, and you have to stop until it's made enough room for you to resume shooting. Other cameras might not be able to use their buffers for their highest resolution files but will let you keep shooting if you chose a lower-resolution setting. It's a tough choice, but sometimes the ability to keep shooting overrides the desire for the highest possible resolution. |
Things that affect latency (that you can control) are:
- Media: Some forms of media accept data faster than others. CompactFlash cards tend to write information faster than microdrives (tiny hard disk drives). Some CompactFlash cards write data faster than others. Look for ones rated for faster write times (frequently marked 4X, 8X, or 12X).
- Resolution: The more data the camera has to write to the card, the greater the latency period. A non-compressed format such as TIFF can take the longest to write. If you can get by with a lower-resolution setting, you can speed up things considerably. After you give up quality, you can't get it back however. On the other hand, missing a shot because you're waiting for your last few images to write to your memory card is one of the more frustrating experiences for a photographer. Film photographers miss shots while changing rolls of film, but digital photographers miss them because of latency.
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