Tools - Digital Cameras
Digital cameras are great for doing high-speed photography, because you can instantly see what you photographed. And you don't have to waste film on all those shots that didn't capture quite the instant you wanted. We recommend using digital SLRs for greatest creative control. There are many available at reasonable prices. When we first wrote this section not too many years ago, you had to pay about $5000 for a good digital SLR. We put good in italics, because what was good 5 years ago is low end today. Nowadays, you can get much-improved cameras for $500.
We provide information in this section on:
- Features to look for in a digital camera
- Advantages and disadvantages of digital cameras
- Thermal CCD noise and how to deal with it
- Gallery of example photographs taken with digital cameras
- How we used to have to take high-speed photos with a digital camera (see Oly.D-600L)
- Manual focus control: Room lights are usually turned out before taking a high-speed flash photograph. In a dark room, a camera in autofocus mode will hunt continuously for something on which to focus. With manual control, the camera can be focused before the lights are turned out.
- Manual aperture control: For high-speed flash photography, the flash unit is used off camera. This requires that the camera aperture be set manually for the expected flash exposure on the subject.
- Manual shutter control: The shutter is held open in a dark room in readiness for the flash discharge. This usually requires a bulb setting, or, alternatively ...
- Shutter durations of at least 1 second: For most high-speed photographic situations, it's possible to initiate the high-speed event in a time period of about a second. For example, for a balloon burst, the shutter button can be depressed and the balloon popped before the shutter closes a second later. This works because human reaction time is typically under a second. Shorter shutter durations can be used successfully, but 1 second provides a margin for error.
- Ability to disable the built-in flash: Many digital cameras have built-in flash units. It must be possible to disable this flash. The high-speed event is captured with an external flash.
- Override control: Some digital cameras won't allow you to take a picture if the subject is too dark and you're not using the built-in flash. The camera should provide a way to override this annoying feature. If not, there is a way to get around it. A pen light can be shined into the camera's photocell as the shutter is opened.
- AC power adapter or rechargeable batteries: Some digital cameras go through batteries quickly. An AC power adapter is a convenient accessory. While having a power cord connected to your camera is inconvenient for candid photography, it's no problem when the camera is mounted on a tripod for high-speed photography. Rechargeable batteries are good if they don't have to be recharged often. The rechargeable lithium batteries that Sony cameras use hold a charge for a long time. Rechargeable AA NiMH batteries used in many digital cameras need more frequent recharging.
The advantage of immediate playback of recorded images is one that makes the digital camera attractive for capturing momentary events. With immediate playback, one doesn't have to develop and print film before deciding on how to improve a photographic setup. With these cameras, it's also possible to output images to a video display.
A disadvantage of digital cameras used to be that the image resolution didn't match that of conventional film. However, resolution isn't really an issue anymore unless you're using an older digital camera.
One problem that the chips in digital cameras have is that they generate random electrical signals that degrade image quality at long exposure times. This problem may become particularly noticeable for exposures of several seconds. However, chips are improving, and noise is becoming less and less of a problem. Some cameras have built-in processes for minimizing noise. If, however, you're using an older camera that has noise problems, keep the exposures less than a second. If you need to remove thermal noise from an image, it can be removed in the image-editing process without significant degradation of the important information in the image. Examples are provided on the next page.