The A99 features the same semi-transparent mirror technology as the previous APS-C SLT cameras. That huge, thin mirror constantly redirects around 30% of the light to a dedicated phase-detection sensor in the roof of the mirror box.
A faint reflection of the AF-sensor's optics can be seen in the mirror in this image.
The other aspect of the SLT design is an electronic viewfinder. The A99 uses the same high-resolution OLED as we've previously seen in the A77 and A65. It's impressively detailed and generally very nice to work with.
The A99 has a locking mode dial on its left shoulder, which includes three customizable settings positions. Unusually for a recent Sony, there's only one 'Auto' position.
You can select whether this engages Intelligent Auto or the Superior Auto mode, that will use the camera's auto HDR or Multi-Shot Noise Reduction modes if it thinks them necessary,
In addition to its huge rear LCD and high-res electronic viewfinder, the A99 also finds room for a traditional top-plate LCD. There are plenty of photographers who are used to shooting with one, so we think it's a nice inclusion.
The A99 becomes one of the first Sony Alphas to features a hot shoe compatible with the ISO 518 standard. Just forward of the flash contacts, you can see a series or communication pins under the front lip of the shoe. This allows use with dedicated flashguns or other accessories. An adapter for using Minolta-mount flashguns in included in the box as well.
The A99's joystick can be used to select the focus point while shooting, and allows quick navigation of the camera's menu and its Fn menu. It's well placed for easy access with your thumb and will be immediately familiar to users of high-end Sonys.
Below the lens release button on the front left of the camera (as viewed from behind), is the new silent control dial. This dial rotates smoothly and steplessly, and is activated by pressing the central button.
The function performed by the dial can be defined in the menus or by holding the central button down. It can be set separately for stills and movie shooting.
The A99 features dual card slots. The upper position is compatible with both SD and Memory Stick, the lower one only with SD.
The writing behavior can be adjusted. The options are:
1) Manually switch between cards
2) Write everything to both cards
3) Duplicate only stills
Duplicate only movies
Stills to one card, movies to the other
JPEGs to one, Raws to the other
The A99 uses the same NP-FM500 battery that we've seen in high-end Sonys going back many years. It's a large capacity, 11.8Wh unit, from which the A99 will extract 500 shots (410 using the EVF), according to CIPA standard testing.