Understanding and Comparing Additional Features |
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What are the other features to look at when comparing digital photography equipment? |
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| Aspect Ratio |
Aspect ratio refers to the ratio between the width and the height of the image. Common aspect ratios are given below. |
- 35 mm Film: 1.50 (size 36 x 24 mm)
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- Computer Monitor: 1.33 (size = 1024 x 768 pixels)
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1.50 (size = 4 x 6 inches) |
| 1.25 (size = 8 x 10 inches) |
- Stationary: 1.29 (size = 8.5 x 11 inches)
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| Burst Mode |
Burst mode is a feature on digital cameras which allows you to capture a series of images in quick succession, which produces a "time-lapse video" effect. The two points of comparison for burst mode are the number of images which can be taken and the image quality. |
| The number of frames can vary from as little as four to as many as sixteen or more. This can vary depending on the amount of memory available. |
| The quality of images in burst mode is often of lower resolution than is normally available; however, this will vary between cameras. |
| Color Depth |
Color depth is calculated as two to the power of the number of bits used to record/display the image. |
- Black and white (1 bit per pixel): 21, or 2 colors
- Windows display (4 bits per pixel): 24, or 16 colors
- Gray scale (8 bits per pixel): 28, or 256 colors
- 256-color (8 bits per pixel): 28, or 256 colors
- High color (16 bits per pixel): 216, or 65 thousand (65,536) colors
- True color (24 bits per pixel): 224, or 16 million (16,777,216) colors
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| Delays |
Startup Delay: the delay between when the camera is turned on and when it is able to take a picture. |
| Refresh Delay: the delay between when you press the shutter button and when the camera captures the image. |
| Processing Delay: the delay while the captured image is processed and stored. |
| Macro |
Macrophotography generally refers to images which are captured at larger than life-size. Macro mode on a digital camera or camcorder is different in that it refers to the ability to get very close to the subject. |
| When capturing macro images, there are several points to keep in mind: |
- The camera should be parallel to the subject.
- The camera must have stable support (either a tripod or other stable surface).
- Using either the timer or the remote will minimize blurring caused by camera movement.
- The flash should not be used, as it will overexpose the image.
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| Metering System |
Digital cameras use light meters to automatically determine the correct exposure. There are three ways this is done: spot metering, center-weighted metering, and matrix metering. |
| Spot metering uses a spot in the center of the viewfinder to determine the exposure. This allows you to control the exposure to best capture a particular part of the subject. |
| Center-weighted metering uses the entire image area but calculates the exposure by giving more importance to the center of the image. Extremely dark or light areas in the subject can cause the exposure calculated by center-weighted metering to be inaccurate for the image. |
| Matrix metering also uses the entire image; however, it breaks the area down into smaller segments and uses the individual readings to calculate the best possible exposure. Matrix metering is the most accurate of the metering systems. |
| Mini Movie Mode (limited MPEG) |
Mini Movie Mode could be considered an extended Burst Mode. The difference between the two is that the mini movie mode allows you to capture a short period of motion video and audio (usually measured in seconds), as compared to the simple time-lapse video provided by Burst Mode. |
| Video Stabilizer |
Video stabilization refers to a method (either optical or digital) which reduces the shakiness often seen in hand-held shots. Originally, this was a feature primarily found in camcorders, but it has become more common to find the feature in digital cameras as well.There are two types of video stabilization: optical and digital. |
| Optical video stabilization uses floating optical elements to counteract the vibration caused by the user. Optical stabilization is the best method. |
| Digital stabilization uses software to counteract the shakiness of the image. While effective, it does not work as well as optical stabilization. |
| Motion Video Audio Recording |
Camcorders (whether digital or analog) are designed to capture both audio and video. There are two types of audio recording available: 2-channel and 4-channel. |
- 2-channel audio recording captures 48 kHz / 16-bit audio. This is the standard audio recording method.
- 4-channel audio recording captures 32 kHz / 12-bit audio, which allows you to dub an extra audio track onto the tape afterwards.
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| Motion Video Formats |
There are five common video formats associated with motion video: NTSC, AVI, MPEG, RealVideo and QuickTime. |
| NTSC: This is the standard composite video format used in the United States. |
| AVI: Microsoft® Audio/Video Interleaved digital file format |
- AVI, Type 1: interleaved audio and video stream
- AVI, Type 2: separate audio and video stream, older format
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| MPEG digital file format (see also Motion Picture Experts Group website) |
- MPEG 1: Coding of moving pictures and associated audio for digital storage media at up to about 1.5 Mbits. Basis for MP3 and Video CD format.
- MPEG 2: Coding of moving pictures and associated audio information. Basis for digital television converters and DVD format.
- MPEG 4: Coding for digital television, interactive graphics applications, and interactive multimedia (combining MPEG 1 and MPEG 2 capabilities).
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| RealVideo®: Streaming audio and video format which supports AVI, WAV, MIDI and MPEG. Requires RealPlayer® or RealOne® Player (Free). |
| QuickTime®: Streaming audio and video format developed by Apple®, which can store video, audio and still pictures. Supports most encoding formats, including MPEG-1, MPEG-2 and MPEG-4. Requires QuickTime viewer (Free). |
| Panorama Mode |
A panorama shot is an extremely wide-view image. Normally, panorama images are captured in one of two ways: |
| Manual Panorama: A manual panorama shot requires a stable shooting surface (such as a tripod) and continuous light levels while the pictures are taken. Starting at either the extreme left or extreme right, take a picture, move the camera 30% to 50% in the other direction, then take another picture. Once all pictures have been taken, they can be merged using image editing software. |
| Panorama Mode: Some digital cameras have an automatic panorama mode, which allows you to capture panorama images with less effort. The exact method may vary between cameras. |
| Remote Control |
A remote control allows you to capture images without having to stand behind the camera. This allows you to include yourself in the shot and to capture images from difficult vantage points. |
| Timer |
A timer allows you set the camera to capture an image or images after a set delay. This is primarily used for capturing images which include the photographer. |
| Zoom |
When comparing the zoom ratings between cameras, you should look at the number of zoom options (2x, 3x, etc) and whether the zoom function is optical or digital. The difference between the two can be best illustrated by comparing the images that would result from using a 6X zoom to focus in on a single flower. Where the 6X optical zoom lens produces a clear, crisp image of the single bloom, the 6X digital zoom simply magnifies the original image, producing a pixelated image. Unless you are comparing two cameras which only have digital zoom, the optical zoom rating should be the only type considered. |
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Optical zoom is a true, lens-based zoom and results in a larger image at the same resolution, with an increase in image information. An example of a simple optical zoom is the small handheld cameras which have a magnifier that slides in front of the main lens. |
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Digital zoom is done via internal software rather than being lens-based; it produces the same effect as is obtained by magnifying the image size through image editing software and is subject to pixelation, as illustrated at left. |
