The Alpha 580 – a three-way view
Once I had a quarterplate hand-and-stand camera, vintage 1920s. Attached to the front standard was a small reflex viewfinder, giving a miniature composition you could use at waist or chest level. On the same standard was a folding wire frame, with a companion eye-sighting window flipping up from the side of the body. This gave a direct view from eye level. But for the most accurate framing and focusing, a groundglass screen at back could be used with the shutter open and a viewing hood folded out.
Those three ways of viewing have never been available in a modern SLR. Until now! The Alpha 580 (for which you can also read 560 throughout this review, give or take the sensor) is the first modern SLR to offer three entirely different viewfinder systems, all with their own unique focus and exposure methods. There have been cameras made by Alpa and Praktina which had optical finders tucked in alongside their pentaprism, and Rollei invented a finder which could switch from eye-level to waist level at the flick of a lever. But the Alpha 580 offers three through-the-lens systems and it’s unlikely any DSLR will do so again.
This is a 10-page article – please use the navigation bar at the bottom to move on to the next page, or click the ‘Continue Reading’ link to view as a single long article (this function is not very reliable though and may produce an ‘undefined’ error)
The three finder methods
To clarify, the 580 has the two principal modes of the A3xx and Axx series predecessors – conventional mirror-prism eye level finder, and the so-called Quick Live View on the tilting rear screen. This live view is not fed from the shooting sensor, instead a small CCTV camera sited in the prism housing presents a webcam quality view of the focusing screen itself.
Ken Rockwell found this labelling on Sony cameras annoying, but then, almost anything annoys Ken… funny thing is they have missed out a big extra label for REAL live view with contrast-detection AF
Like the little reflex viewer on the 1920s camera, this allows easy waist or chest level composition, with limited accuracy. The focus screen itself only shows 95% of the final image, and the Quick LV camera crops this further to show just 90%. Depth of field can not be seen any better than by eye (e.g., badly) and although the 580 has a stop-down preview button this function is disabled in Quick LV. But Quick LV keeps the fast, accurate 15-sensor phase detect AF module in operation allowing 5 frames a second shooting.
Since the QV camera system is not the actual sensor, it not only shows various finder markings as seen by the eye, it also does not reflect colour or exposure settings precisely. It can simulate them using manual exposure or +/- control, and use auto gain to operate in low light. It also takes over exposure metering when used, replacing a standard 40-sector honeycomb TTL metering module with 1200 colour sensitive zones. In the latest models including the 580 it allows Face Detection and Smile Shutter. So it’s not all that bad, but the image is only VGA and can not be enlarged to check focus.
Focus Check LV in action, including showing the effect of +1 over-ride and of tungsten WB in this shot
From the A450 (brief blip on the radar with a fixed rear screen), A500 and A550 onwards Focus Check Live View has been added to Alpha cameras at this level. This is true sensor-fed LV showing 100% of the picture with accurate preview of contrast, exposure and colour. It can preview depth of field perfectly and magnify the image 7.5X or 15X (7X/14X for the 560). Until these latest models appeared, AF was not possible in this mode, it was strictly as labelled – ‘Focus Check’ using manual focus.
With the 580/560, contrast detect autofocus has been enabled along with 1080p HD video. I believe this could be have been implemented in the 500/550 generation, as I fed the Focus Check LV via HDMI cable to a television and the output quality was both excellent in quality and not limited to any shorter duration than typical HD clips (in 2009). Sony chose not to, as they did not yet have the lenses needed for contrast detect autofocus on the mainstream Alpha mount system