Pentax *ist-DPentax's first d-SLR is a winner, with good color, low noise, and excellent "hand feel," all in a compact body.<<Optics :(Previous) | (Next): Shutter Lag & Cycle Time Tests>> Page 6:Exposure & FlashReview First Posted: 03/30/2004 |
Exposure
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What Pentax calls "Green Program" mode is more like a traditional full Auto mode on other digicams, as the camera automatically controls the entire exposure. Hyper Program AE mode leaves the camera in charge of aperture and shutter speed, but you can turn the Av and Tv command dials to select from a range of equivalent exposure settings. Turning the Tv (front) dial biases the exposure toward shutter speed, while the Av (rear) dial biases the exposure toward more or less depth of field. (You can disable this feature through the Custom settings menu.) The *ist D offers more control over the Program AE mode than most digicams, as you can set up the metering system to bias the exposure toward a faster shutter speed (Hi Speed Program Line) or more depth of field (Depth Program Line). You can adjust the program line through the Custom Function menu, which offers an unusual "MTF" program setting to bias the exposure towards the aperture at which the lens will be at its sharpest, as well as a Normal setting. (This "MTF" mode is unique, as far as I know. It's no secret that most lenses are at their sharpest at medium aperture settings, getting softer and showing more distortion at both very large and very small apertures. What the "MTF" mode tries to do is to set the lens aperture somewhere near its "sweet spot," and then adjust the shutter speed to produce the correct exposure. Pretty slick!)
Shutter and Aperture Priority exposure modes provide control over one exposure variable while the camera controls the other, and Manual mode provides total user exposure control. If the camera disagrees with your chosen settings, the aperture and shutter speed values blink in the status display and viewfinder. An interesting feature in both Manual and Hyper Program modes is the Green button on top of the camera, which returns you to the default metered exposure settings. By default, pressing the button adjusts both aperture and shutter speed to the default exposure, though a Custom menu option sets the button to adjust either aperture or shutter speed only. In Bulb mode, the exposure time is limited only by how long the Shutter button (or cable release) is held down and the amount of battery time available (a good case for the AC adapter). (Of course, there'll be a practical limit to how long you can expose for, as sensor noise will swamp the image of your subject after a while.) There's also a depth-of-field preview feature, accessed by turning the Power switch to the aperture icon. This stops down the lens to the set aperture, giving you an idea of what the depth of field will be, and also turns on the backlight for the top-mounted LCD info display.
ISO can be set to a range of values from 200 to 3,200 by turning the Mode dial to the ISO selection and rotating the Tv dial to select the value. A Custom menu option offers "Wide" and "Normal" ISO ranges, with the Normal setting ranging only from 200 to 1,600, and the Wide setting expanding the available range to 3,200. Like any digital camera, the *ist D's image noise will increase as you boost the ISO setting, but I found that the *ist D generally did very well in the noise department. Its noise levels are generally a bit below those of its competitors, up to ISO levels of 800 or so. (A little lower than the Canon EOS-10D and Digital Rebel, a good bit lower than the Nikon D100.) Beyond that, it does a bit worse than the competition, but not by much.
The *ist D has another handy feature that relates to ISO setting. Called "Sensitivity Correction," it lets the camera automatically adjust the ISO value (either up or down) if your chosen shutter speed or lens aperture in Hyper Program or Shutter or Aperture Priority mode would result in an incorrect exposure with the current ISO setting. You can turn this function on or off via a Custom Function menu entry, but it strikes me as being very useful for times when you care more about just getting the shot than what the particular ISO speed you happen to be shooting at. It's a little like telling the camera: "OK, try to shoot at ISO 400, but if you really have to, go ahead and boost (or cut) the ISO beyond that point to get the shot for me." There will certainly be times when you won't want the camera to do this, but for those times, it's easy enough to just disable this option in the Custom Function menu.
White balance can be set to Auto, Daylight, Shade, Cloudy, Fluorescent (with options for white, neutral, and daylight fluorescent lighting), Tungsten, Flash, or Manual modes. In Manual mode, you can set the color balance by holding a white card in front of the lens and pressing the Shutter button while holding down the Manual White Balance button on the front of the camera.
Three metering options are available on the *ist D: 16-segment Multi, Center-Weighted, and Spot. The 16-segment Multi setting divides the image area into 16 zones and determines the level of brightness in each zone and the contrast levels between zones before determining the best overall exposure. Center-Weighted metering measures light from the entire frame but places the greatest emphasis on a circular area in the center. Spot metering is pretty self-explanatory, taking a reading from the dead center of the image (most useful when using the AE Lock function). Exposure compensation is adjustable from -3 to +3 exposure equivalents (EV) in one-half step increments, and is controllable in all exposure modes. (Through the Custom menu, you can set the step size to one-third step increments.) The AE Lock button on the rear panel locks the exposure reading until the button is pressed a second time, or the Shutter button is fully pressed. Through the Custom menu, you can set the AE Lock feature to link the AE area to the selected AF area, useful for photographing off-center subjects.
An Auto Bracketing feature takes three shots of the same subject with varying exposure values determined by either the photographer in Manual mode or by the camera in all other modes. Exposure settings for bracketing can vary from -1.5 to +1.5 EV (values are added to the already chosen exposure compensation value), with step sizes of one-third or one-half EV unit, and the bracketing biased toward either underexposure, overexposure, or centered around the main exposure value. The *ist D also features a Self-Timer mode, which counts down from either two or 12 seconds once the Shutter button is pressed before actually making the exposure.
Through the camera's settings menu, you can adjust the image Sharpness, Contrast, and Saturation levels, in three steps. A Color Space option under the Custom menu offers sRGB and Adobe RGB color options as well.
Consecutive Shooting Mode
The *ist D offers a Consecutive Shooting mode that captures a rapid series of images, at intervals of 0.41 seconds in my testing. I noticed that the camera could capture a maximum of five images, regardless of resolution setting, before slowing down to transfer files from the buffer memory to the CompactFlash card.
Multiple Exposure Mode
The Auto Bracketing button on the *ist D also accesses the Multiple Exposure mode, which lets you overlap multiple images to create a single image. You can capture as many as nine exposures for a single image, and the current combined image is displayed on the LCD monitor for a few seconds after each image is captured.
Flash
Built into the *ist D is a pop-up flash unit, which operates in Auto, On, Off, or Red-Eye Reduction modes. A small button on the side of the flash unit releases the flash, while the Flash Mode button on the top panel cycles through the available modes. The built-in flash has a guide number of 15.6 (at ISO 200/m), and 11 at ISO 100/m. This rating matched my own test results pretty well, giving a range of about 9 feet with the 18-35mm f/4.0-5.6 lens I did most of my shooting with. The *ist D also features a top mounted hot shoe with X-contact for Pentax dedicated flash units, and a sync socket on the side for connecting an additional external flash.
The *ist D supports the Pentax AF360FGZ dedicated external flash unit, which provides a range of enhanced features. With the internal flash alone, the maximum flash-sync speed is 1/150 second. With the AF360FGZ attached though, a high-speed flash sync mode permits proper flash synchronization at any shutter speed the camera is capable of. The *ist D can also control the AF360FGZ as a wireless remote strobe, while still retaining full TTL flash metering. In this mode, the *ist D's internal flash can either be used solely as a controller of the remote flash, or can be configured to contribute to the flash exposure as well. When an external flash is connected, you can set the built-in flash to fire as the master, or as the controller for the other flash unit.
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