Sony Alpha 99 at a glance:

  • 24.3-million-pixel, full-frame, Exmor CMOS sensor
  • Fixed translucent mirror design (SLT)
  • ISO 100-25,600 (extended to ISO 50)
  • 2.359-million-dot XGA OLED EVF
  • 3in, 1.228-million-dot dual articulated LCD screen
  • Dual AF system with 19-point phase detection and 102-focal-point sensor
  • 10fps high-speed burst shooting
  • Weather-sealed magnesium-alloy body
  • Street price £2,299 body only

Sony Alpha 99 review – Introduction

A lot has changed during the four years between the launch of Sony’s original flagship full-frame DSLR, the Alpha 900, and the arrival of its replacement, the Alpha 99. While both use the same lens mount and a full-frame sensor with an approximate 24-million-pixel resolution, there are few other similarities. The launch of the Alpha 99 means that Sony’s current Alpha range is made up entirely of SLT (single lens translucent) models rather than DSLRs. So, from the entry-level Alpha 37 through to the Sony Alpha 99, all the cameras use a fixed translucent mirror rather than the moving mirror set-up of a traditional DSLR.

When SLT technology was introduced two years ago in the Alpha 33 and Alpha 55, we went into detail about the impact this set-up has on the handling and image quality of the cameras (AP 9 October 2010), and the same information applies to the Sony Alpha 99. A fixed translucent mirror set-up works by allowing approximately 70% of the light through to the imaging sensor, and redirects the remaining 30% to an AF sensor.

Benefits of the SLT system over the direct competition include full-time live view and phase-detection AF, and fast frame rates because the mirror is fixed and does not need to move between frames. However, there is a concern about the impact that a 1/3EV reduction of light reaching the sensor has on image quality, particularly in low-light performance. Also, as only 30% of light would be directed to the viewfinder, an optical type would be too dark so an electronic viewfinder (EVF) is used instead.

Recently, Sony has been one of the leading innovators in new camera technology, and this in turn provides unique selling points for its cameras. These will be crucial as the company tries to include the Alpha 99 into a professional market long dominated by competitor brands. The Sony Alpha 99 is up against the likes of the Canon EOS 5D Mark III and Nikon D800, so it will have to offer something that its rivals don’t.

To this end, the company has been working hard, particularly on the Alpha 99’s autofocus, and on paper everything looks very good. However, the true test is when the camera is in the hand. I am therefore keen to see how the Alpha 99 performs in the sorts of situations a professional would use it, and whether Sony’s SLT technology is appropriate for this market.

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