Thursday, 4 September 2008

A900 Quick Comments

Image courtesy of Xitek

The leaks have begun just under a week before the official announcements on the 9th/10 September next week. A leaked ad from National Geographic and a Danish photography magazine have confirmed the name as Alpha 900. Other salient details include:

  • 24.6MP CMOS EXMOR sensor (as announced earlier in the year)
  • Dual BIONZ processor
  • Intelligent Preview
  • 100% Viewfinder 0.74x
  • 3 inch, VGA Hybrid LCD (Same as the A700 presumably)
  • 9-point Centre Dual-Cross AF (with f2.8 sensor and 10-point wide-area assist)
  • 5 fps
  • SteadyShot Inside

It's pretty much what was expected. I may make a few speculations and comments as on some of the details.

As the previously announced 24.6MP 36mm x 24mm sensor was specified with a 6.3fps (12 bit) maximum frame rate, the 5 fps seems reasonable. I hope, though don't expect, that a low-noise, "slow-scan" mode could be employed which lowered the frame-rate but reduced read-noise by operating the ADCs closer to their optimal corner frequency. Unless the dynamic range of the sensor can exceed 12 bits, I do not see a compelling reason to use more than a 12 bit RAW bit depth.

The data throughput of the A900 is twice that of the A700, ganging up two BIONZ processors is a simple way of handling this. It will be interesting what processing Sony decides to implement, especially after the "cooked RAW" issue.

Intelligent Preview could indicate an off-the-main-sensor live view, with Live View being reserved for the fast-AF style of live view as in the A350 and A300. Intelligent Preview could possibly be a way of differentiating (delineating) this type of pre-capture composing. It is presumably not suitable for quickly moving subjects and more suitable for posed, macro and landscape style photography.

The viewfinder coverage and magnification is quite good. In comparison, the Dynax 9 film camera had a 100% 0.73x viewfinder.

The rear LCD seems to share the same specifications as the one in the A700. I suspect that it may be hinged similarly to the A300/350 as a photo of a prototype spotted in Canada could have shown such a feature (unfortunately the photo was not clear enough to positively identify this).

The AF set-up is not entirely clear but it could be interpreted as meaning having 9 dual-cross sensors, of which the central one is f/2.8, and a further 10 (line) sensors to assist wide-field AF tracking. I speculate that the 9 dual cross (x and + type) sensors cover the central rectangle of the frame corresponding to an APS-C sensor. A further 10 sensors would lie outside this region to help with peripheral subjects. Having the 9 most sensitive AF sensors in covering the central region would be ideal for use with a 10/12MP "crop-mode", either with use with DT lenses or in order to boost frame-rates (though I doubt the latter as this would mainly be constrained by the mirror/shutter assembly, though some sort of electronic shuttering in Intelligent Preview mode could be possible). It is ambiguous at this stage whether the f/2.8 sensitivity is only for the single centre dual-cross sensor or extends to all 9 dual-cross central sensors. Edit 1: Possibly, in keeping with how the A700 AF system is described, only the centre AF sensor is dual cross, the other 8 main AF sensors could be line or single cross sensors. The 10 additional wide-field sensors may not be user selectable. Edit 2: Dual-cross probably doesn't mean + and x, but two crosses side by side as on the A700.

"SteadyShot Inside", as opposed to SuperSteadyShot, is an intriguing change of terminology. I suspect that it is merely a marketing rebranding of SuperSteadyShot to eliminate the "Super" as it may not fit in with the image of cameras at the high end of the market. Time will tell whether the effectiveness of the image stabilisation on the A900 is comparable to the systems employed on the APS-C sensor cameras.

Of course, we have no reliable indication as to the pricing position of the camera, especially in comparison to the Nikon D700. It is expected that Sony will announce several new lenses to complement the existing range, especially the ZA 24-70mm/2.8 SSM. A ZA 16-35mm/2.8 SSM is strongly rumoured to be among these. A replacement for the 70-200mm/2.8 G SSM is an outside possibility. Telephoto lenses may also be announced, especially as the 300mm/2.8 G SSM is the longest (non-mirror) prime lens in the Sony line-up.

It will be interesting how the A900 will be received, not by the minority of online forum posters, but by the general photographic community. The A900 could serve as a "halo" product, much as the existence of the ~US$8000 Canon 1DsIII has for Canon. Its importance could extend to much beyond its immediate sales but as a symbol of Sony's commitment to the Alpha system. I will eagerly awaiting the first user reports in the hands of real photographers. For most, the A900 is not appropriate for their style of shooting but for those who can make the most of the resolution (with nice glass), it looks at this point to be a very promising tool.

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