Canon PowerShot Pro1New level of sophistication takes over the top spot in the PowerShot line.<<Optics :(Previous) | (Next): Shutter Lag & Cycle Time Tests>> Page 6:Exposure & FlashReview First Posted: 05/14/2004 |
Exposure
| Free Photo Lessons | |
|
Shutter Priority mode puts you in control of the shutter speed setting (with a range from 1/4,000 to 15 seconds), while the camera chooses a corresponding lens aperture. As with the Program AE mode, you maintain control over all other exposure options. Aperture Priority works along similar lines, except that you control the aperture (f/2.4-3.5 to f/8) and the camera chooses the best shutter speed. Both the shutter speed and aperture values are displayed on the LCD monitor. If the camera doesn't agree with the exposure settings you've selected, the numerals indicating the automatically-determined exposure variable (aperture, when in shutter-priority mode, or shutter speed, when in aperture-priority mode) on the LCD will turn red when you half press the Shutter button, letting you know that either the aperture or shutter speed needs to be corrected. In both Aperture and Shutter Priority modes, you can quickly adjust the designated exposure variable by simply turning the control dial.
In Manual mode, the control dial adjusts both settings, you just press down to alternate between aperture and shutter speed. A nice touch in manual mode is that the camera acts as a light meter, indicating via numerals in the upper left-hand corner of the screen how much over- or under-exposure (in EV units) it thinks will result from your chosen aperture and shutter speed. If the exposure error exceeds 2 EV, the number remains at plus or minus 2, and turns red.
Several preset exposure modes are also available for shooting under special conditions. Portrait mode uses a large lens aperture setting to reduce the depth of field, resulting in blurred backgrounds and strong focal emphasis on the primary subject. Landscape mode uses a small aperture to keep both the foreground and background in sharp focus. A slow shutter speed is also common in Landscape mode, so it's recommended that you use a tripod. Night Scene mode uses a slow shutter speed to capture the color and detail of an evening setting, along with a flash exposure to illuminate the primary subject in the foreground. When slow shutter speed and flash are used together, the overall scene is more evenly exposed. This mode can also be combined with the Red-Eye Reduction flash for portraits, or you can cancel the flash altogether. A tripod is also recommended when working in Night Scene mode, and portrait subjects should be warned to remain still after the flash, until the shutter is closed.
A quick-review mode allows you to confirm the recorded image immediately after exposure. To access the Review mode, you can simply continue to hold down the Shutter button after the exposure. The just-captured image will remain displayed on the LCD until you release the Shutter button. (I really like the convenience of this feature, as it's easy to access when you want it, without tying you down with long review times when you don't need them.) Or, you can turn on the Review function through the Record menu, which displays the image for anywhere from two to 10 seconds, in one-second increments. You can immediately erase the image by pressing the trash can button, which pulls up a small erase menu on the bottom of the monitor. Press the Set button to complete the erasure (this is faster than the G-series, which used to require a press on the right arrow button before pressing Set).
Just as on the G3 and G5, the Pro1 offers the ability to decide after you've shot a photo whether you want to save it to JPEG or RAW file format. If the camera is set to record normally in JPEG format, you can elect to save the just-captured image to a RAW file by pressing the FUNC button at any time during the image-review period. (Whether you're reviewing the image by continuing to hold down the Shutter button, or via a preset review period programmed through the setup menu.) This seems like a handy option, as you could elect to save any images with problematic exposure as RAW files to maximize the data you'll have to work with on the computer after the fact.
Exposure compensation can be adjusted from –2 to +2 exposure values (EV) in one-third-step increments. The camera's metering system offers three operating modes: Evaluative, Center-Weighted Averaging, and Spot Metering. Evaluative metering looks at a number of points throughout the frame, and evaluates the brightness range and distribution between them to come up with the best exposure setting. Center-weighted averaging is based on an averaged reading of the overall scene, plus a reading from the center of the viewfinder or LCD monitor. Spot metering reads only the center of the image, the area that falls within the crosshairs of the viewfinder or within the small square that pops up on the LCD monitor when you press the Spot Meter button. Spot metering is useful when you're shooting under backlit conditions. In these situations, you can use the spot meter to obtain a reading of the area you want properly exposed, then lock the exposure with the AE Lock function, (activated by pressing the "*" button on the back panel in record mode), and recompose your shot for the final exposure. (Note: depressing any other button on the camera will disengage the Spot Metering function.)
Through the Record menu (Spot AE Point submenu), you can also link the Spot Metering area to the FlexiZone AF point described earlier. When the Spot AE Point option of "AF Point" is selected, and the spot metering option is activated, the AF box acquires a set of inner brackets indicating that spot metering is active, and that the AF box is where the metering is being done. If the Spot AE Point is set to "Center," the white brackets will appear in the center of the LCD screen, indicating that this is where the Spot AE metering is being done, regardless of the position of the AF point. This is great for portraits, where both metering and focusing on the face will usually get better results.
The Pro1 offers nine White Balance modes, including Auto, Daylight, Cloudy, Tungsten, Fluorescent, Fluorescent H (for daylight-balanced fluorescents), Flash, and two separate Custom modes, accessed by pressing the WB button on the four-way navigator. The Custom mode lets you manually set the white balance by holding a white card in front of the camera and pressing the "*" button to set the value. Having two Custom settings makes it easy to move back and forth between scenes with radically different lighting. (An example might be a shooting assignment that had you moving between indoor and outdoor spaces at night, with different types of artificial lighting used in the two settings. You could set one Custom white balance for the indoor shots, and the second for the outdoor ones.)
ISO film speed equivalents are set in a submenu of the FUNC button, with choices of Auto, 50, 100, 200, or 400 ISO values. The higher the ISO setting, the more you can extend the camera's exposure range in low-light situations, but keep in mind that image noise increases in more or less direct proportion to the ISO value. Other manual exposure adjustments in the Record menu include Sharpness, Contrast, and Saturation controls.
When comparing the Pro1 to digital SLRs like the Rebel, 10D and higher, it's important to note that though you'll get higher overall resolution in number of pixels captured with the Pro1's 8 megapixel sensor, you get far greater exposure latitude in terms of ISO, with less noise, on the physically larger 6.3 megapixel sensors. The Pro1's ISO range is 50 to 400, whereas the Rebel's is 100 to 1600 and the 10D's is 100 to 3200. These latter two have larger sensor areas, which means bigger pixels. Bigger pixels (7.4 microns on the Rebel, compared to 2.7 microns on the Pro1) can gather more photons. More photons gathered means less signal amplification is necessary, and thus less noise in the resulting image (noise can be thought of as error introduced by signal amplification). More photons also means that the signal (charge in the CCD pixels produced by light from the subject) will be that much greater than noise (charge in the CCD pixels resulting from leakage currents within the sensor itself).
Many may be concerned that the Pro1's higher-resolution sensor means that it has smaller pixels and thus more noise than the G5 sensor, but Canon assures us that the pixel size actually has not changed between the two cameras. To increase the resolution to 8 megapixel, they merely increased the chip size, changing it from a 5 x 7mm chip (.55 inch) to something closer in size to a 8 x 10mm (.66 inch) chip. My own noise measurements seem to bear this out.
Flash
The
Pro1's built-in flash is of the pop-up variety, and operates in any one of nine
available modes. You can leave it turned off, have it fire all the time, or
only fire automatically, as the camera sees fit. In any of its active modes,
you can turn on red-eye reduction (which illuminates the bright AF assist light
on the front of the camera before the flash fires, to make your subjects' pupils
contract), or enable Slow Sync mode, which combines the flash with a slower
shutter speed to allow more light from the scene to enter the lens. The combination
of off plus two active modes (forced or auto) with four variations each (normal,
red-eye w/o slow sync, red-eye w/slow sync, and slow sync w/o red-eye) adds
up to nine modes total. The main flash modes of off, forced on, and auto are
selected via the Flash/Zoom button on the Pro1's top front panel. Slow Sync
and Red-Eye Reduction modes are controlled via the Record menu. Through the
same menu, you can also specify whether the flash syncs with the first or second
curtain. (That is, on shots with slower exposure times, the flash can fire either
as the shutter opens, or as it's closing.)
The flash exposure can be adjusted from -2 to +2 EV in one-third-step increments by using the FUNC button on the camera's back panel together with the Four-Way Arrow pad to access the Flash Exposure Compensation adjustment menu. You can also lock the Flash Exposure Setting (FE Lock) for a specific area of your subject, just as you would with a normal exposure. Simply center the portion of the subject you want to have metered and press the "*" button to lock the flash exposure. The flash will fire single pulse to lock the exposure reading, then you can recompose your image and make the exposure with the FE Lock in place. (Note that pressing any other button after the "*" button will cancel the flash exposure lock.) Canon rates the Pro1's flash effectiveness from 1.6 to 16 feet (50 centimeters to 5 meters), a figure that agreed quite well with my own test results. (This is a more powerful flash than found on most consumer-level digicams.)
In addition to its built-in flash, the Pro1 features a hot shoe for mounting more powerful external flash units. Canon recommends using its own Speedlight 220EX, 380EX, 420EX, 550EX, MT-24EX Macro Twin Light, or MR-14EX Macro Ring models, but other manufacturers' models should work as well, albeit with less-complete integration with the camera's own controls. The Pro1's flash sync speed is a maximum of 1/250.
Canon's handling of the sync-speed limitation on the Pro1 bothers me a little though, as it did on the G3 and G5 before it. If you're in Auto or Program AE exposure mode, all is well, the camera simply won't select a shutter speed greater than 1/250 when the flash is enabled. In Tv (shutter speed priority) or Manual mode though, you can select shutter speeds as fast as you want (all the way up to 1/4,000), but if you have the flash turned on (forced flash is the only mode available, the Auto option is only offered in Programmed exposure mode), the actual shutter speed will be restricted to 1/250! I disagree with this design choice. When a camera is in a mode that gives the user control over some parameter or other (such as shutter speed), the camera shouldn't arbitrarily override the user's settings. While the Pro1 does show you that the shutter speed has changed to 1/250 when you half-press the Shutter button, it's easy to miss seeing the changed shutter speed unless you're on the lookout for it. I guess it's good that the camera tries its best to deliver you a well-exposed shot, but I'd really like to see some way of optionally preventing an override like this. Once the shutter button is released, it resumes displaying the shutter speed you've set, further confusing matters.
Carried over from the G-series is automatic Speedlight EX recognition in Aperture-Priority mode. When the camera senses that a Canon EX-model external flash is mounted and in ready mode, it automatically sets the shutter speed to 1/60 second, overriding the normal tendency of Aperture-Priority metering to set the shutter speed based on available lighting. This is very handy, as you can attach an EX-model flash unit, set the camera to Aperture-Priority metering, and then just turn the flash on or off as you wish, without worrying about what the shutter speed is doing. Note though, that the Pro1 must be in full manual mode to use with non-Canon flash units. (Since the Aperture Priority mode will normally select a very slow shutter speed when an "unrecognized" flash unit is attached and the scene is dimly lit.)
Auto Exposure Bracketing
The Auto Exposure Bracketing (AEB) mode is another function controlled by the FUNC button's sub-menus. It automatically captures a series of three images, each at a different exposure setting. You can manually set the exposure step size in one-third-step increments, covering a range from -2 to +2 EV, by depressing the FUNC button, scrolling to the AEB option with the Four-Way Arrow pad, and then using the Main dial or left and right arrows to choose the amount of variation between exposures. Depress the Set button to make your selection, then fully depress the Shutter button to start the series. The camera makes all three exposures with just one press of the Shutter button. In AEB mode, the exposures are chosen to bracket whatever exposure setting you've dialed in using the Exposure Compensation adjustment. Thus, the bracketing always occurs around whatever exposure you've chosen based on your evaluation of the scene and the camera's metering.
Note that Auto Exposure Bracketing cannot be used with flash photography. If the flash fires, only one image will be recorded.
Continuous Shooting
Controlled by the Continuous / Self-Timer / Wireless Remote button on top of the camera, the Pro1's Continuous Shooting mode captures multiple consecutive images at up to 2.5 frames per second (fps) in High Speed mode (only 1 frame per second in Standard Continuous mode). This frame-capture rate may vary slightly, depending on image quality, and functions in use. (In my own testing, the Pro1 consistently delivered 2.59-2.61 frames/second, in a variety of JPEG size/quality modes, but only for the first four frames in a burst. After that, it dropped to about 1.5 frames/second for anywhere from two to 19 frames, depending on the image quality setting.) The Pro1 will continue to capture images as long as the Shutter button is depressed, or until the camera's internal memory fills up. When recording RAW files, the camera can record four shots in high speed continuous mode, at a rate of about 0.73 frames/second.
Both continuous modes capture data directly to the buffer memory, but the "standard" continuous mode does some amount of the signal processing on the fly. The result is that cycle times in normal mode are slower, but the camera can generally record much longer bursts before having to pause to empty its buffer, particularly when working with smaller image sizes and lower quality settings. High Speed continuous mode captures more quickly, but doesn't do the processing on the fly, with the result that fewer shots can fit in the buffer memory before having to empty it.
As alluded to above, the Pro1's buffer memory seems to operate in a two-stage fashion, buffering up to four large/fine JPEG images quite quickly in continuous mode, then dropping to slightly lower shooting speeds for the next two, before finally being forced to wait for the data to transfer to the memory card for each shot taken. In single shot mode, with a reasonably fast memory card (I happened to test with a 24x Lexar unit), you can grab a large/fine JPEG shot about every 1.61 seconds, for up to 17 shots or so. Beyond that point, the camera slows pretty immediately to a pace of 3.9 seconds or so between shots, depending on card speed. This is overall pretty good performance for an 8-megapixel camera. (Some reviewers have apparently measured the continuous-mode cycle time for JPEG files across all six shots that the camera can capture before slowing to card-speed levels, with the result that they report much slower times than the camera is actually capable of in four-shot bursts.)
Movie Mode
The Pro1 also offers a Movie mode, which is accessed by turning the Mode dial on top of the camera to the miniature movie camera symbol (a camera will appear in the upper left corner of the LCD display). The AVI / Motion JPEG files are recorded at either 320 x 240 or 160 x 120 pixels, at approximately 15 frames per second. Recordings can last as long as three minutes at either resolution setting, depending on the amount of memory available on the CompactFlash card. To begin recording, you simply press the Shutter button once. A red dot icon appears in the upper right-hand corner of the LCD screen, indicating that recording is in progress, and a counter in the lower right-hand corner begins counting up to show the length of the current clip in seconds. To stop recording, simply press the Shutter button again. (Note that the recording options are largely preset in Movie mode: Macro mode, Resolution, Exposure Compensation, White Balance, Manual Focus, Picture Effects, self-timer, wireless delay, and AF assist beam are the only adjustable functions.)
When finished, you can view the recording by toggling the power switch to the playback position. Pressing the Set button brings up a little VCR-style playback control panel, with buttons for play, fast forward and fast reverse, go to end and go to beginning. A scissors icon lets you trim the movie to select just the part you're most interested in, and save it to the memory card as a separate file. When the movie is playing back, the control panel disappears, but you can stop playback by hitting the Set button again.
Quicktime(tm) is required to view the AVI/Motion JPEG files recorded by the Pro1 in Movie mode. Quicktime is included with current versions of the Mac OS (any version later than 8.5), and a QuickTime player for the Windows platform is included on the Solutions Disk bundled with the camera.
Stitch-Assist Mode
The Stitch-Assist mode records a series of overlapping images that can be stitched together to create horizontal or vertical panoramas or stacked, 2 x 2-frame rectangular composites. A framing guideline for each format appears in the LCD monitor to help line up successive shots. After each shot, a portion of the image remains on-screen, as an aid to lining up the next image in the series. For the horizontal and vertical panoramas, you can take up to 26 images in a series, enabling you to record a full 360-degree circle of the surrounding scenery. For horizontal or vertical panoramas, you can set the camera to record the series of images either right to left or left to right, top to bottom, or bottom to top. The 2 x 2 mode uses a series of only four images, starting from the top left corner and moving in a clockwise direction, to create a complete composite. Once the images are downloaded, you can use Canon's PhotoStitch program to seamlessly combine them in your computer. This is of the more complete stitch solutions we've seen.
Self-Timer Mode
The Self-Timer button on top of the camera also controls the Continuous Shooting and Remote operating modes. When set to the Self-Timer / Wireless mode, the camera displays the standard self-timer icon (a clock face with one hand) in the LCD display, and the self-timer icon with a remote symbol in the LED panel on top of the camera. When in Self-Timer mode, depressing the Shutter button activates either a 2- or 12-second countdown, as selected via the Record menu. During the countdown time, the red Self Timer light on the camera's front panel blinks, gaining speed in the last two seconds. If the camera's Beep function is turned on in the Setup menu, the camera will also beep during the countdown. While in Self-Timer mode, you can also trigger a zero-, two-, or 10-second countdown by pressing the Shutter button on the remote control, regardless of the self-timer delay chosen in the Record menu. This delay is set in the Record menu under Wireless delay.
Interval Shooting
The Pro1 also features a built-in intervalometer, that lets you program the camera for extended time-lapse exposure sequences. You can choose intervals between successive photos ranging from one to 60 minutes, and anywhere from two to 100 photos in the series. This opens lots of opportunities for interesting time-lapse shots, but be sure to use the optional AC adapter for any long sequences to avoid any interruption of power.
Remote Sensor/Transmitter
The Pro1's Wireless Remote Control allows you to trigger the camera from as far away as 16.4 feet (5 meters) from the front sensor, and as far as 3.3 feet (1 meters) from the right side sensor. The range of the remote control will depend somewhat on ambient lighting and the angle you're at relative to the front of the camera. Range in bright sunlight will be much less than in a darkened room, and you'll get more range when you're directly in front of the camera than when you're to one side. The Pro1 lets you set the shutter delay when using the remote to zero, two, or ten seconds. (The no-delay option is particularly welcome, as most digicams with IR remotes have a minimum delay of two or three seconds.) Besides simply triggering the shutter, you can also use the IR remote to adjust the optical zoom lens with its two Zoom buttons, and activate the LCD monitor with its Display button. With the LCD monitor rotated so that it faces you, you can use the Zoom buttons on the remote control to compose the image and the Display button to scroll through the LCD information screens to check exposure settings. In Replay mode, the remote control can be used to scroll through stored images, scroll around areas within a magnified image, view an index of up to nine captures, and replay movies, very handy for presentations using the built-in video output.
Reader Comments! --> Visit our discussion forum for the Canon PowerShot Pro1!
Follow Imaging Resource: