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After two-plus years of claiming they're not going to incorporate video capture into their DSLR product line until they can overcome the limitations of DSLR capture—i.e, no autofocus and viewfinder blackout during video capture—Sony has introduced two compact DSLRs that address both issues.
The Sony Alpha a33 and Sony Alpha a55 are a pair of interchangeable-lens DSLRs that make good use of a couple of interesting camera technologies, including one not seen for a couple of decades, to solve a couple of modern-day DSLR video-capture roadblocks.
The Sony Alpha a33 and Alpha a55 both make full use of Sony Alpha a-Series optics, and the differences between them are the resolving power of their respective APS-C format Exmor HD CMOS imaging sensors and the quality of their video capture—a 16.2Mp sensor and 1080p video in the Alpha a55, and a 14.2Mp sensor and 720p in the Alpha a33.
The first part of Sony's solution to the present day "DSLR-video dilemma" has to do with the mirror assembly, which in the case of the Sony Alpha a33 and Sony Alpha a55 are fixed, translucent mirrors that allow light to pass through them, rather than the mirrors lifting up and out of the way each time a picture is taken. By incorporating what Sony is calling Translucent Mirror Technology into the new cameras, Sony's engineers were able pull off a trifecta of technical goals—continuous autofocus while shooting video, uninterrupted image viewing through the viewfinder when shooting stills (JPEGs and/or RAW) and video and still capture burst rates of up to 7 frames per second in the Alpha a33 and up to 10 frames per second in the Alpha a55, making it the fastest frame-banger to date among current video-enabled DSLRs.
The concept of using a pellicle mirror as a method of increasing frames-per-second burst rates is not a new one. It was used originally in the Canon Pellix SLR in 1965 and last used in Canon's EOS RT film SLR back in 1989, which was capable of firing up to 10 frames per second, which was even more impressive back then, although it's mighty impressive today.
Sony's solution to the autofocus and blackout quandary has been addressed by replacing the pentaprism/pentamirror housings used on traditional DSLRs with a high-res (1,440,000-dot) Tru-Finder electronic viewfinder (EVF), which under bright viewing conditions replicates the viewing experience of an optical viewing system remarkably well. Once the sun goes down, though, the Tru-Finder EVF becomes as noisy as the rest of the lot, at least on the pre-production camera we tooled around with for a few days prior to the official announcement. Nonetheless, the EVFs on the new Sonys, which feature a 60 fps refresh rate, are a huge step forward in terms of clarity than comparable EVF offerings.
A plus side of the Tru-Finder EVF is that it makes it possible to view the same exposure and scene mode data you'd normally only be able to view on the camera's variable-angle tilt 3" Xtra Fine Live View (921,600-dot) LCD, which can be swiveled 270° horizontally and 180° vertically. It should also be noted that you can view 100% of the total image area on both the LCD and Tru-View eye-level finder.
One particularly handy visual aid you can bring up onto both the Xtra Line Live View LCD and Tru-Finder is a Digital Level Gauge, which while some may find distracting (and they can always turn it off if they do), this user found mighty handy especially when shooting in video mode.
Both the Tru-Finder EVF and Live View Xtra Fine LCD enable you to display histograms and gridlines as well as preview the look of all Scene modes and/or color settings, i.e. exposure compensation, white balance and creative styles in true WYSIWYG fashion when shooting stills or video. The Tru-Finder EVF also allows you to zoom in for critical eyeballing of your pictures, just as you would with the LCD, without having to fend off glare when shooting under bright lighting conditions.
The lack of image blackout made possible by the pellicle mirror system also aids in boosting what is already a very responsive 15-point TTL Phase Detection autofocus system, which performed equally well on our pre-production test camera indoors and out, and that's using the camera's Sony DT 18-55mm f/3.5-5.6 SAM kit lens. We would imagine the AF system will prove to be even more responsive when used with any of the faster Sony AF optics. And like all other Sony Alpha DSLRs, the new cameras work equally well with any older Minolta AF lens you might have knocking around.
In addition to "normal" still shooting, both cameras feature Sony-centric shooting modes that have been incorporated into many of Sony's digicams including Handheld Twilight mode, which enables you to shoot sans tripod in near darkness by capturing six rapidly-captured, ISO-boosted exposures, sampling them and editing the sharpest, best-exposed portions of each into a single, optimized (and surprisingly noise-free) image. Low-light shooters can also take advantage of the camera's Night Portrait and Night View modes, as well as the ability to boost the ISO ratings from a native ISO 100 up to an extended ISO equivalent of 25600.
Even in brighter lighting conditions, Multi Frame NR enables you to go beyond single-frame capture by allowing you to capture six rapid-capture frames and synthesize them into a single optimized image at any ISO rating in order to squeeze every last bit of detail from the shadows and highlight areas.
Additional tone-expanding shooting options include Auto HDR and D-Range Optimizer, and as with all Sony DSLRs, both cameras feature SteadyShot INSIDE image stabilization, which enables sharper imagery with all Sony and Minolta AF lenses.
Sweep Panorama mode is another Sony shooting mode that's been incorporated into the new cameras. This mode captures up to 65 individual images and combines them into a single ultra-wide (12416 x 1856) panoramic image for incredibly dramatic landscapes, architectural and interior imagery.
Switching from stills to video and back is also easy with the new Sonys and is accomplished by simply pressing the One-Touch Movie button, which is located on the top deck, just to the right of the EVF eyepiece. Both cameras also feature built-in stereo mics, which are located on the right and left side of the EVF housing. You have the additional option of using more advanced shoe-mounted mics, which are available from Sony as well as third-party manufacturers. There's also a built-in GPS device in the a55 that automatically tags your photos and videos with coordinates in the EXIF data
Both cameras record images in a choice of sRGB or Adobe RGB, and you can expect to shoot about 330 exposures per charge (of its 7.2V, 1020mAh InfoLITHIUM battery pack, part number NP-FW50), which can be recorded onto Memory Stick PRO, Memory Stick PRO-HG, SD, SDHC, or SDXC memory cards.