Olympus Camedia C-770 Zoom4.0 megapixels, a sharp 10x zoom lens, a unique flash head, and loads more features!<<Optics :(Previous) | (Next): Shutter Lag & Cycle Time Tests>> Page 6:Exposure & FlashReview First Posted: 07/06/2004 |
Exposure
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The C-770 Ultra Zoom offers an impressive amount of exposure control,
including Auto, Program, Aperture Priority, Shutter Priority, and Manual exposure
modes, as well as a small handful of scene modes that preset exposure and color
parameters for shooting in specific situations. The Full Auto and Scene modes
make the camera easy to use for novices, while the other options provide the
flexibility demanded by more advanced users. All capture modes are set by rotating
the Mode dial on top of the camera, which also accesses the My Mode, Movie,
and Playback modes. (My Mode lets you create a custom setup for the camera,
including settings for virtually every exposure and operating parameter. The
saved setup can then be selected simply by rotating the Mode Dial to the "My"
position. See below for more information.)
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In Auto mode, the camera has complete control over the exposure parameters. You can adjust options like lens zoom, drive mode, image size, etc., but can't make any exposure adjustments at all (not even exposure compensation or white balance, this is truly a "point-and-shoot" mode). Program mode leaves the camera in charge of the aperture and shutter speed, while you control the remaining exposure options such as ISO, metering, and white balance. In Program mode, you also have access to the exposure compensation adjustment, which lets you adjust the camera's automatically determined exposure setting by plus or minus two exposure equivalent (EV) units, in steps of 0.3 EV. Aperture Priority lets you set the aperture from f/2.8 to f/8 (the bottom end of which depends on the lens zoom position) leaving the camera to automatically determine the appropriate shutter speed, down to 1 second. In Shutter Priority, you can select shutter speeds from 1/1,000 to 1 second, with the camera selecting the corresponding aperture setting. The Manual exposure option lets you control both aperture and shutter speed yourself, and the bottom end of the shutter speed range is extended to 15 seconds. In common with other Olympus cameras, a handy feature of the Manual mode is that, as you scroll through the various exposure settings, the camera indicates whether it thinks your chosen setting will produce a correct exposure. It does this by showing the f/stop, shutter speed, and exposure differential (the difference between your settings and what the camera metering system thinks is correct) in green, up to a limit of +/- 3EV. For exposure differentials outside that range, the numbers turn red and remain fixed at the 3EV reading. (This is a very handy feature that I'd like to see more manufacturers implement in their cameras' manual exposure modes.)
The four scene modes include Portrait, Sports, Landscape, and Night Scene, which optimize the camera for specific shooting situations. In Portrait mode, the camera uses a larger lens aperture, reducing depth of field to throw distracting background elements out of focus. Sports mode biases the exposure system toward faster shutter speeds, to help freeze fast-moving subjects. Landscape mode keeps foreground and background in focus, adjusting the camera's color handling to emphasize blue and green hues in the image (producing more intense foliage and sky colors). Night Scene employs slower shutter speeds, allowing more ambient light into the image. Limited menu options are available in the scene modes, as their purpose is to simplify camera setup for novices. (A multitude of menu choices would only add complication to what are intended to be easy-to-use camera settings.)
The C-770 features a variable ISO setting, which lets you set the camera's light sensitivity to 64, 100, 200, or 400 ISO equivalents, or to an Auto mode in which the camera selects an ISO appropriate to the subject's brightness. The higher sensitivity settings, combined with the camera's maximum 15-second shutter speed and noise reduction option, provide excellent low-light shooting capabilities. The higher ISO settings are also helpful when you want faster shutter speeds under normal lighting, to help freeze fast action. Of course, as with all digicams, the higher ISO settings produce photos with more image noise, in much the same way that higher-ISO films show more film grain. To combat this problem, the C-770 offers a Noise Reduction mode through the Record menu, which greatly reduces the amount of image noise from long exposures, particularly at the higher ISO settings.
Two metering systems are available on the C-770: Spot and Digital ESP. Both are accessed through the Spot / Macro / DPOF button on the camera's back panel. Under the default Digital ESP setting, the camera takes an exposure reading from the center of the image as well as the surrounding area and chooses the best exposure based on brightness and contrast across the entire scene. Spot metering simply reads the exposure from the very center of the image, so you can pinpoint the specific area of the photograph you want properly exposed. (Spot metering is very handy when you have a subject that's backlit, or that has a very different brightness, either lighter or darker, than the background.)
An AE Lock button locks the current exposure settings whenever pressed, so you can independently lock exposure and focus. (AE Lock is useful when you want to base your exposure on an off-center subject. Point the camera at the subject, lock the exposure, then recompose your shot however you like. Your subject will be correctly exposed, regardless of what might be in the center of the frame when you finally snap the shutter.)
For precise manual control over exposure metering, an eight-point Multi-Metering mode is available when in Spot metering mode. Enabling the Multi-Metering option through the Record menu lets you take up to eight single readings throughout the frame, which are then averaged to get the best exposure. I particularly like way the C-770 displays exposure information in Multi-Metering mode. You select individual metering points by pressing the AEL button, and each time you do so, the relative exposure for that point is displayed on a little ruler-graph at the bottom of the LCD screen as soon as you select the first point. Once the exposure graph is displayed, a small green pointer above the line shows the relative brightness of the subject under the central metering spot in real time. Pressing the AEL button captures the current brightness value to incorporate in the exposure calculation, and adds a green marker arrow under the graph at that point. In this way, you can very easily see the range of exposure values represented in your subject, and choose how you want to weight them in the final exposure determination. (You can also bias the exposure toward a particular part of your subject by simply adding more exposure samples from that area.) This one of the most flexible and powerful exposure metering options I've seen on a digicam, incidentally first seen on the still coveted Olympus OM-4 film camera, and is another feature other manufacturers would do well to emulate. (The screen shot shown above right is actually taken from the previous C-740 model. The feature works identically on the C-770, but the aperture, shutter speed, and AEL indicator displays are arranged a little differently.)
A Record View function, enabled through the Record menu, displays the most recently captured image on the LCD screen while the image is recorded to the memory card. There's also a Quick View function that lets you check the previously captured image, by pressing the new Quick View button. Quick View basically drops you into Playback mode, with all playback functions (zoom, scroll, index display, delete, voice annotate, etc) available, but with the camera able to switch back to Record mode instantly, whenever you half-press the Shutter button.
In situations where exposure compensation is necessary, simply press either the right or left Arrow buttons (in all exposure modes except Auto and Manual) and the EV value displayed on the LCD will increase or decrease in one-third-step increments, up to a maximum of +/- 2 EV. Or, you can use the Auto Exposure Bracketing (AEB) function to automatically bracket an exposure as much as +/- 2 EV in either three or five step increments of 0.3, 0.6, or 1.0 EV units each. The auto bracketing will center its efforts around whatever exposure you've chosen as the starting point, including any exposure compensation adjustments you've made. AEB is really handy for those times when you want to make sure you get just the right exposure for a critical subject.
White balance options include Auto, Daylight, Overcast, Tungsten, Daylight Fluorescent, Warm White Fluorescent, Cool White Fluorescent, and Custom, to accommodate a variety of lighting situations. You can also adjust the white balance, adding either more red or blue. This ability to "tweak" the white balance is very helpful when dealing with difficult light sources.
The C-770 Ultra Zoom also offers a 12-second Self-Timer for self-portraits or those occasions when you don't want to risk camera shake on a long exposure by pressing the Shutter button to trip the shutter.
There are also options on the Record menu to set the in-camera image sharpening, contrast, and saturation, in arbitrary units from -5 to +5. The contrast option is one that I personally find appealing. I find that I often want to decrease a camera's default contrast somewhat, to help preserve highlight detail on contrasty subjects. In the same general realm, you can also record images in black-and-white or sepia tones, or capture text via the Whiteboard and Blackboard photo modes, as set via the camera's Function sub-menu..
Flash
The C-770 offers a built-in, pop-up flash, with six operating modes: Auto, Red-Eye Reduction, Fill-in Flash, Flash Off, Slow Sync, and Slow Sync with Red-Eye Reduction modes. Auto mode lets the camera decide when to fire the flash, while the Fill-in mode fires the flash with every shot. (Fill-in is useful for throwing light on backlit subjects, keeping their faces from being obscured in deep shadow.) The Red-Eye Reduction mode fires a brief burst of low-power flash pulses before firing the flash at full power, making the pupils of your subject's eyes contract, reducing the occurrence of the Red-Eye Effect. Slow Sync allows more ambient light into the background, producing more natural lighting behind a flash-illuminated subject. Through the Record menu, you can set the Slow Sync flash to fire at either the beginning or end of the exposure. A button on the rear panel pops the flash up from its compartment, while the Flash / Protect button on the back panel controls the flash operating mode. You can also adjust the overall flash intensity from +/-2 EV through the Record menu.
What can be viewed as either a blessing or a curse is the manual control for the popup flash. Often a flash that pops up whenever the camera happens to think it should can be annoying or surprising, especially if you disagree. With the C-770, the flash only fires if you've popped it up yourself. If the light level is too low for a good exposure without the flash, an onscreen warning tells you that you should press the manual pop-up release; if you don't the camera does its best to make the shot work anyway.
Unique Dual-Tube Flash Head
I mentioned the C-770's unique dual-tube flash head earlier, but it's worth a little further discussion here, given how unusual it is. Essentially all long-zoom digicams face dual problems in their flash systems. For one, the flash head on a long-zoom camera needs to spread its light across a wide enough angle to cover the field of view of the lens at its widest-angle position. This means though, that when the lens is zoomed to its full telephoto position, most of the light emitted by the flash is wasted, lighting up parts of the scene that are well outside the field of view. This "wasted" flash power would be a big enough limitation as it is, but long zoom lenses also generally suffer a fairly significant decrease in light-gathering efficiency as they approach the telephoto end of their focal length range. Taking the C-770's lens as a case in point, it has a maximum effective aperture of f/2.8 at its widest angle focal length, but only f/3.7 at the telephoto end of its range, almost a full f-stop (factor of two) reduction in its light-gathering ability. The net result is that flash systems on long zoom digicams tend to have rather limited working ranges when the camera's lens is set to the telephoto end of its range.
Professional-grade dedicated external flash units address this problem with flash heads that "zoom" right along with the camera lens, concentrating the light from the flash tube into a progressively narrower beam as the focal length of the camera's lens moves from wide angle to telephoto. This works fine if you have the size and bulk of a typical external flash unit to work with, but there isn't nearly enough room (or money in the manufacturing budget) to allow a solution of this sort in a prosumer digicam.
Olympus found a very clever way around this dilemma though, as seen in the C-770's internal flash design. While it wasn't practical to incorporate a zooming flash head, Olympus achieved much the same effect at dramatically lower cost and bulk with a dual-tube flash head that covers wide and telephoto focal lengths separately. The upper tube in the flash head is set in a shallow reflector, to provide even coverage at wide-angle focal lengths, while a second tube located below it sits in a much larger, deeper reflector, to focus its light into a much narrower beam. By concentrating the light in this way, the "telephoto" reflector significantly increases the useful range of the flash head, without requiring higher-power circuitry, with all the space, cost, and battery-life penalties that would imply.
In use, the camera automatically switches between the two flash tubes when the lens is zoomed through the midpoint of its focal length range: The top tube is used at short focal lengths, while the bottom one is used at longer ones. This all happens without any user input, the net effect simply being that of a camera with much-improved flash range at telephoto focal lengths.
In my own shooting with the camera, the dual-tube flash head seemed to work very well, with the C-770 much more able to capture distant subjects at night.
This strikes me as an elegant solution to the problem of telephoto flash performance, one that I expect to see other digicam manufacturers adopt for their long-zoom models as well. The incremental cost of the second flash tube should be fairly modest, and very little circuitry should be needed to switch between the two tubes, making the whole solution pretty cost-effective. Kudos to Olympus for this creative solution to a widespread problem!
Special Exposure Modes
Movie and Sound Recording Modes
The C-770's Movie mode is accessible via the Mode dial on top of the camera (marked with a small movie camera symbol). Once in Movie mode, you can record QuickTime or MPEG4 movies with or without sound. The length of movie clips depends on the resolution setting and the amount of memory card space available. A number indicating the available seconds of movie storage on the memory card appears on the LCD and EVF monitors. Optical zoom is disabled while recording movies with sound, but is enabled when recording with the sound turned off, and most other exposure options are available in movie mode as well. (Note though, that when zooming during movie recording, it can take quite a while for the autofocus system to adjust to changes in zoom position - As much as several seconds may elapse after a large zoom adjustment before the image becomes sharp again.) Three image resolutions are available in Movie mode, 640 x 480, 320 x 240 and 160 x 120 pixels. Olympus doesn't specify what the frame rate is in the C-770's movie mode, but recording time is limited only by the available space on the memory card. An added enhancement on the C-770 over it's lower-end sibling the C-765 is an option for recording its highest-resolution movies as MPEG4 files, rather than the default motion JPEG format. Note that movie files take up a lot of card space. The included 16 MB xD card holds only 17 seconds of movie with sound at the 640 x 480 resolution setting, 46 seconds at 320 x 240, and 186 seconds at 160 x 120. You'll definitely want a large memory card if you plan to do much movie recording.
In any record mode, you can record a short sound clip to accompany still images. The Sound option in the record menu activates the mode, and you can record a maximum of four seconds per image. Sound recording begins approximately half a second after the shutter is released. You can also record sound after the fact, through a menu option in Playback mode. Thanks to its built-in speaker, you can play back both sound clips and sound-accompanied movies on the C-770, a feature the lower-priced C-765 lacks.
Panorama Mode
Like most Olympus digicams, the C-770 offers a Panorama exposure mode when using an Olympus brand panorama-enabled xD-Picture Card. In this mode, the exposure and white balance for a series of shots are determined by the first exposure. The Panorama function provides light blue guide lines at the edges of the pictures to help you align successive shots, leaving enough overlap between them for the stitching software to be able to do its job. Up to 10 shots can be taken in a panoramic series. Once the sequence of images is downloaded to your computer, you can use the included Olympus software to assemble them into an extended panorama.
Note that the panorama function is only enabled by the built-in firmware found on Olympus brand memory cards, so this option isn't available when using third-party memory cards. (I have to say that I think this tying of the panorama function to Olympus-branded cards strikes me as one of the most ill-considered product decisions Olympus has made. I can't imagine that the number of memory cards Olympus sells through this mechanism balances the camera sales they lose by having a crippled panorama function. On the other hand, for occasional panorama shots, most users can probably get by with the memory card included in the box with the camera.)
"2-in-1" Mode
Accessed through the Record menu, "2 in 1" photography mode records two vertically-oriented, half-sized images in a single frame of memory. After capture, the images are saved side-by-side as one full resolution image, giving a split-screen effect. As with Panorama mode, a set of guidelines appear in the LCD display, to help you line up the shots.
Sequence Mode
The C-770 also offers three Sequence modes that mimic the motor drive on a film camera, recording images in rapid sequence when you hold down the Shutter button. As is usually the case, the number of frames you can capture quickly is limited by the camera's buffer memory capacity (typically three SHQ-quality images), and sequence mode isn't available at all for the TIFF (uncompressed) image format. What's a little surprising is that, once the buffer fills, you have to release and re-press the shutter button before the camera will capture any more frames. (In continuous capture mode, many cameras will simply keep snapping images whenever they're able, as long as you hold down the shutter button and there's space available on the card.) Hi-Speed sequence mode captures two frames, at a slightly faster frame interval. AF Sequence mode also captures a continuous series of images, but adjusts the focus between each shot, resulting in much slower shot to shot times.
My Mode
Accessed by turning the Mode dial to the "My" position, this mode lets you save customized settings and then access them simply by turning the Mode Dial. For example, if you consistently shoot in the same environment, you could save the exposure settings for those specific shooting conditions, so that they can be instantly recalled. (I can imagine this option being very handy for situations where you might have to switch quickly between two different environments. Think of a wedding reception, for instance: Standard "program" mode for outside shots on the lawn, etc, but a custom setup in My Mode to shoot the indoor scenes under incandescent lighting.) My Mode even lets you edit the Shortcut menu items, which appear when the Menu button is pressed, to reflect often changed settings. A total of four different sets of My Mode settings can be saved. The C-770's My Mode is very flexible, letting you preset the following camera parameters (see the subsequent section on camera modes and menus for explanations of any settings which might not be obvious from the list below):
- P/A/S/M exposure mode
- Lens default aperture
- Default shutter speed
- Exposure compensation
- LCD on
- Lens zoom setting
- Flash mode
- Macro/spot metering setting
- Self-timer on
- Drive setting (single, sequence, etc)
- AF/MF
- ISO
- Flash exposure compensation
- Slow Synchro mode
- Noise Reduction
- Multi-Metering on
- Digital zoom enabled/disabled
- Fulltime AF enabled/disabled
- AF mode
- Super Macro on/off
- Panorama enabled/disabled
- "2in1" enabled/disabled
- Function setting
- Information display
- Histogram on/off
- File size/quality
- White balance
- White balance adjustment
- Sharpness
- Contrast
- Saturation
- Sound memo on/off
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