Sony DSLR-A580 Exposure
Sony Alpha A580 Exposure Options
The Sony A580 offers all the same exposure options you'd expect in a mid-range SLR camera, plus a few Sony-specific options. Available exposure modes include Program AE, Aperture Priority, Shutter Priority, and Manual modes, with shutter speeds from 1/4,000 to 30 seconds, as well as a Bulb setting available in Manual mode only, for longer exposures. The x-sync speed for flash photography is 1/160 second. A fully automatic mode places the camera in control of almost all functions, to try to deliver optimum results under a wide range of conditions. Basic options such as exposure compensation aren't available to the photographer in this mode, but the A580 will still allow you to select from a subset of drive modes and flash modes, lock exposure with the AEL button, focus manually or automatically, and enable or disable the face detection and smile shutter functions. The Sony A580 also offers a number of Scene modes, including Portrait, Sports Action, Macro, Landscape, Sunset, Night View, Hand-held Twilight, and Night Portrait, all accessed from a shared Scene (SCN) position on the Mode dial. There's also a separate Flash Off mode which merits its own position on the dial, as does a Sweep Panorama mode that captures and stitches a multi-image panorama with a single press of the shutter button. A Multi Frame NR function likewise captures multiple images with a single shutter press, but then merges these into a single exposure with reduced noise. See the Modes and Menus page for more details.
When framing using the Live View or Focus Check LV modes, the Sony A580 offers an optional live histogram function in all operating modes. Located near the bottom right corner of the LCD panel, it's rather small, and offers only a luminance readout rather than a full RGBY histogram, but it's still very useful for ensuring your exposures are correct. Another feature that's rather more common, but still very welcome, is the exposure display, visible both on the LCD for Live View shooting, and in the optical viewfinder's info display, when the camera is in Manual exposure mode. This shows the amount the camera thinks an image will be over- or underexposed within a range of +/-2.0EV, based on the settings you have selected, to help you find the best exposure for the subject. (Beyond the 2.0EV range, arrows on either end of the scale blink to emphasise that the metering system's limit has been reached.) Together, the live histogram and exposure display make it relatively easy to get suitable exposures even when shooting manually.
Sony A580 Face Detection
The Sony A580 includes Face Detection capability, capable of locating up to eight faces in the scene simultaneously. This information is taken into account when determining several exposure variables -- focus, exposure, flash and white balance. The A580 doesn't go as far as some cameras that try to recognize specific individuals, nor is it able to differentiate between adult and child faces. It does, however, includes a related feature that is now pretty common in point-and-shoot cameras, but relatively unknown in large-sensor cameras. Dubbed "Smile Shutter", this allows the A580 to automatically trigger the shutter, capturing photographs by itself when a smiling face is detected within the image frame. The A580's implementation is perhaps best suited to portraits of individuals, since the shutter is tripped when only one face within a group is smiling. There's a three-step control over the degree to which a subject must smile before the shutter is tripped. and when Smile Shutter is enabled, the A580 also provides a graph at the left of the screen that indicates how close a particular expression has come to passing the required threshold for the shutter to be tripped. In our testing we found the feature a little hit-and-miss, however, consistently spiking to the top of the scale and tripping the shutter for some individuals with barely the slightest smile, even when set to require a big smile. We also noticed that it locked up altogether a couple of times, and stopped detecting smiles until we removed the battery from the camera and reseated it.
Sony A580 ISO Range
ISO sensitivity ranges from 100 to 12,800, a wider range than that offered by many recent SLRs. The ISO sensitivity is adjusted in Program, Priority, and Manual modes by pressing the dedicated ISO button on the A580's top panel, or through the ISO option in the Function menu, and adjustments can be made in one-stop increments.
In Program and Priority modes, but not in Manual mode, an Auto ISO mode is available, and in Auto, Scene, Flash Off, and Sweep Panorama modes, it's the only option. The function is limited to a maximum of ISO 1,600 in all modes.
In addition, the Sony A580 offers a Multi-Frame NR function, which combines multiple shots into a single output image, in a similar manner to the Hand-held Twilight mode. The difference between the two functions is that Multi-Frame NR allows direct control over ISO sensitivity. Multi-Frame NR is available only in the Program, Priority, and Manual modes, and is accessed from the ISO sensitivity dialog. When using Multi-Frame NR, the maximum ISO sensitivity limit is expanded to ISO 25,600 equivalent.
Sony A580 Noise Reduction
The Sony A580 gives you only two choices for High ISO noise reduction, neither of which allows the function to be completely disabled. The default is to leave High ISO NR entirely in the camera's control, but if the maximum image detail is desired (or you prefer to do your noise filtering in post processing), a "Weak" option is also available in Program, Priority, and Manual modes.
A separate Long Shutter noise reduction On / Off setting is available in Program, Priority, and Manual modes, for dark frame subtraction when shooting exposures of one second or longer. If enabled, this approximately doubles the exposure time for each shot, allowing the second dark frame exposure to be captured with the shutter closed.
Sony A580 White Balance Options
White balance modes on the Sony A580 include Auto, Daylight, Shade, Cloudy, Incandescent, Fluorescent, and Flash. A direct Kelvin temperature setting is also available, ranging from 2,500K to 9,900K, as is a Custom white balance setting, for setting white balance from a white or grey card. The A580's popup flash strobe can be used when determining a custom white balance, and unusually, the camera also provides a Kelvin readout of the measured color temperature -- a great feature which lets you subsequently dial the temperature in directly if you're shooting in familiar conditions. The effect of changes in white balance settings is shown in real-time on the LCD monitor.
In all of the preset white balance modes, you can fine-tune the color by pressing the left / right arrow keys on the four-way controller while in the White Balance menu. Blue / red adjustment is possible within a range of -3 to +3 arbitrary units for all but the fluorescent mode, which offers only a -1 to +2 unit range. In Kelvin white balance mode, there's also a color filter function which offers a magenta - green filter within a fairly wide range of -9 to +9 arbitrary units.
Custom white balance is set by selecting Custom Setup from the white balance menu, and pointing the camera at a neutral white or grey card under the lighting you'll be shooting in, filling a frame in the center of the display with the reference target, then pressing the Shutter button.
In addition, the Sony A580 can bracket white balance using the White Balance Bracketing (BRK WB) option in the Drive Mode menu. For each shutter release, the A580 records three separate image files, varying only the white balance between each image. Two step sizes are available -- 10 mireds when using the BRK WB Lo setting, and 20 mired steps with the BRK WB Hi setting.
Sony A580 Metering Options
The Sony Alpha A580 offers three metering modes, selected via the Metering Mode option in the Function menu: Multi-pattern, Center-Weighted, and Spot. All three modes operate on data from the camera's CMOS image sensor. When using the optical viewfinder, the default Multi-segment metering mode divides the image into 40 segments, and compares these to determine exposure. For Live View or Focus Check LV exposures, a much finer-grained 1,200 segment metering zones are evaluated in Multi-segment mode. Center-Weighted gives precedence to the center of the image while reading the whole frame. Spot metering is useful for high-contrast subjects, as it bases the exposure reading on the very center of the image, letting you set the exposure based on a small portion of your subject. When the camera is operating in Auto or Scene modes, the metering mode is fixed to Multi-pattern, and cannot be changed.
By default, you can lock an exposure reading separately from autofocus lock by pressing and holding the AEL button. Alternatively, the AEL button behaviour can be changed so that pressing and releasing the button will set and release the autoexposure lock on subsequent presses.
Sony A580 Exposure Compensation & Bracketing
The Sony A580's Exposure Compensation adjustment increases or reduces the overall exposure from -2 to +2 exposure values (EV) in one-third stop increments, and like White Balance, the effect of Exposure Compensation is simulated on the preview if framing your scene using Live View or Focus Check LV. In addition, the A580 offers -2 to +2 EV of flash exposure compensation, in 1/3 EV increments, set through the Function menu. A Continuous Bracketing feature captures multiple shots with different exposures. See the Drive Mode section on Continuous Bracketing below for more details.
Sony A580 DRO / HDR
The Sony A580 offers two different functions aimed at handling high-contrast scenes, each functioning in a rather different manner. The Dynamic Range Optimization (DRO) function adjusts the tone curve of captured images, bringing out shadow detail without adversely affecting highlights. As well as an Auto DRO mode, there are also five different levels of DRO available. Alternatively, Sony has included a high dynamic range (HDR) mode, which captures three separate images with varied exposures, and then combines the images in-camera, creating a single image with significantly increased dynamic range. The A580 can either automatically select the exposure variation, or a value can be selected manually in 1EV steps within a range of 1EV to 6EV.
The DRO and HDR modes can't be used together, and each brings its own set of advantages and disadvantages. Since DRO only works from a single shot, it must operate entirely within the dynamic range available from the image sensor, where the HDR mode is able to capture a significantly greater dynamic range than is possible in one shot. Since DRO is effectively amplifying the signal in shadow areas of the image, it also brings increased noise (or increased noise reduction) in the shadows. HDR mode, meanwhile, is suitable only for relatively static subjects, given that it requires multiple exposures. Thanks to microalignment capability, Sony's HDR mode is at least able to deal with the slight changes in framing caused by shooting handheld, but subject motion or camera shake will likely cause unacceptable artifacts in HDR images.
Both DRO and HDR can be disabled altogether if desired, although the default on the A580 is for DRO Auto mode to be left enabled.
Sony A580 Hand-held Twilight
Another function which the Sony A580 has inherited from the company's point-and-shoot camera line is its Hand-held Twilight mode, which is accessed from the Scene (SCN) position on the Mode dial. Hand-held Twilight mode shoots a burst of six images with a single press of the shutter button, using as high sensitivity as is necessary to offer hand-holdable shutter speeds. The A580 then combines all six source images into one image with reduced noise in static areas, as compared to a single shot taken with the same exposure settings. Cleverly, Hand-held Twilight mode is able to deal with moving subjects, by making the assumption that the first frame includes your intended subject. Areas of subsequent images which match up with the first image are factored into the final result, but areas that don't match -- either due to subject or camera motion -- aren't used in creating the final image. This does, however, mean that the moving subject doesn't benefit from the same degree of noise reduction as the rest of the image.
The Sony A580's implementation of Hand-held Twilight does have one important difference from the similar mode found on its point-and-shoot siblings. Where the existing cameras have been able to use an electronic shutter to capture the source images, the A580 must instead rely on its physical shutter. The A580's mirror slap isn't the quietest we've heard, and with six frames captured in a rapid burst, its Hand-held Twilight mode can have bystanders turning around in expectation of seeing a paparazzo in their midst. ;-)
Sony A580 Multi-Frame NR
Another function that's closely related to Hand-held Twilight is Sony's Multi-Frame NR mode. Also available in Sony's SLT-series cameras, Multi-Frame NR has several important differences from Hand-held Twilight. Most significantly, it functions in the A580's Program, Aperture- or Shutter-Priority, and Manual modes. In all but Manual mode, it offers the ability to let the camera choose the sensitivity automatically, but unlike Hand-held Twilight it also allows manual selection of ISO sensitivity (and indeed, for Manual exposure shooting, that's the only option given.) One further difference of note is that in Multi-frame NR mode, the maximum ISO sensitivity limit of the Sony A580 is raised from its standard ISO 12,800 equivalent, to an impressively high 25,600 equivalent.
Sony A580 Sweep Panorama
The final mode inherited from Sony's Cyber-shot point-and-shoot lineup is the A580's Sweep Panorama function, with which it can automatically capture a burst of images, and stitch them into a single panoramic image in-camera. Both 2D and 3D modes are offered, with the latter cleverly comparing the relative positions of subjects as they pass the left and right sides of the lens, and using this information to create a 3D image consisting of separate 2D views, stored in a Multi Picture Object file.
Again, since there's no electronic shutter to rely on, the mirror slap noise means you won't be catching anybody by surprise, That said, the feature functions pretty well if you've a reasonably steady hand, and your subject matter isn't too close to the camera. If your subject matter is too close to the camera, or your panning isn't smooth and straight, the seams between separate images can become fairly noticeable. Focus and exposure are locked from the first frame of the panorama, so you'll want to pick your starting point carefully. From there, you can pan left, right, up, or down, simply sweeping the camera across your subject matter after pressing the shutter button.
Two panorama sizes are available -- standard, or wide. Standard horizontal panoramas are limited to 15 megapixels, and vertical panoramas to 8.4 megapixels. In Wide mode, horizontal panoramas are 23 megapixels, and vertical panoramas are 12 megapixels. For 3D mode, only horizontal panoramas are possible, with the standard size providing 5.3 megapixel resolution, and the wide size offering 7.7 megapixels. There's also a 1,920 x 1,080 pixel mode designed to match the resolution of a Full HD display, available only for 3D panoramas.
A darkened mask over the left third of the LCD display shows an area of the frame that won't be included in the final output image, and an on-screen message warns you if the Alpha A580 wasn't able to track your panning, prompting you to recapture the panorama. (Depending on how much was captured, the A580 sometimes retains a partial panorama with the uncaptured portion of the image left as a flat grey.)
Sony A580 Drive Modes
The Sony A580 offers a variety of shooting modes, accessed via a dedicated Drive Mode button on the camera's top deck, or through the Drive Mode option under the Function menu. Available in all shooting modes except Sweep Panorama, and Hand-held Twilight, drive options vary depending on the shooting mode, but include Single Shot Advance, two Continuous Advance modes, Speed Priority Continuous, two Self Timer modes, Continuous Bracket, White Balance Bracket, and Remote Commander. Single-shot, as you'd expect, captures a single image with each press of the shutter button. When using the optical viewfinder, Continuous Advance captures images at either five frames per second in Hi mode, or three frames per second in Lo mode, while the shutter button is held down. With Focus Check Live View, only the five frames per second rate is available, while the standard Live View mode offers only a three frames per second rate. As many as 22 Raw, 20 Raw+JPEG, or 44 Large / Fine JPEG shots can be captured in a burst, adjusting focus and exposure between shots as necessary.
In Speed Priority Continuous mode, the Sony A580 boosts its frame rate even further, to a generous seven frames per second, but with an important proviso. Both autofocus and autoexposure are fixed from the first shot in the burst -- so this mode is only useful for subjects under relatively even illumination, and whose distance from the photographer remains within the available depth of field, unless you've the skill required to pull focus manually.
The Self-timer modes offers a choice of either two or ten second timers. Continuous Bracket mode lets you take a sequence of three shots with either 0.3 EV or 0.7 EV exposure variation steps, with the sequence order being to shoot the metered exposure first, followed by the underexposed and overexposed frames. White Balance Bracket captures three images with varied white balance settings, as describe in the white balance section of this page. Finally, Remote Commander mode configures the A580 to capture images as directed by the optional RMT-DSLR1 wireless remote control, which communicates with the camera via an infrared receiver hidden behind a shiny plastic trim piece in the top of the hand grip's front surface.
Sony A580 Creative Styles
Finally, the Creative Style option on the Function menu allows photographers to set the A580's color mode. Six preset options are available -- Standard, Vivid, Portrait, Landscape, Sunset, and B/W. For all six choices, Contrast and Sharpness levels may be adjusted in seven steps. In addition, all but the black and white mode offer seven-step control over saturation. A separate Color Space option under Screen 3 of the Record menu lets you choose between sRGB and AdobeRGB color spaces, with sRGB being best for viewing images on a computer, and Adobe RGB the best choice for printing images.
The images above were taken from our standardized test shots. For a collection of more pictorial photos, see our Sony Alpha DSLR-A580 Photo Gallery .
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