Sony A9 Technical Info

by Mike Tomkins | Posted: 04/25/2017


Although the Sony A9 looks quite similar to the A7-series at first glance, it sports a newly-designed body featuring magnesium alloy panels at front, top and rear, as well as a magnesium alloy internal frame supporting this external structure. The lens mount is also now said to be more rigid, with six screws instead of four to give it sufficient strength for use with heavy telephoto lenses.

The Sony A9 body is said to be comprehensively sealed for dust and moisture resistance, although the company doesn't specify how many seals are included in total.


Inside its weather-sealed body, the Sony A9 sports the world's first stacked 35mm full-frame CMOS image sensor. The Exmor RS-branded sensor combines a high-sensitivity backside-illuminated design with on-chip memory, allowing for a claimed 20x improvement in readout speed. It also features gapless microlenses.

The sensor has a 3:2 aspect ratio and an effective resolution of 24.2 megapixels from a 28.3-megapixel total resolution. Dimensions of the chip are 35.6 x 23.8mm.


Output from the new image processor is handled by the latest variant of Sony's BIONZ X image processor. Compared to previous versions, it's said to feature a newly-developed image processing algorithm which reduces noise levels across the sensitivity range.


Together, the new stacked sensor and refined processor allow truly spectacular performance, so long as you're willing to use an electronic shutter. (And according to Sony, doing so should prove less of a compromise with fast-moving subjects, as it has greatly reduced the amount of rolling shutter effect that would otherwise send you running for your mechanical shutter.)

At full resolution with an electronic shutter, the Sony A9 is capable of capturing as many as 20 frames per second, and that's complete with autofocus and autoexposure adjustment between frames. If that's overkill for your needs, reduced rates of 10 or 5 fps are also available. But if you opt to disable electronic shutter in favor of the mechanical one, performance is slashed to a maximum of five frames per second, with an even more modest 2.5 fps rate available in Continuous Lo mode.

Burst depth is claimed to be 362 JPEG frames regardless of compression level, or 241 compressed raw frames. Capture both raw and JPEG simultaneously, and this is reduced just slightly to 222 frames. Finally, you can also opt for uncompressed raw, in which case you should see a buffer depth of 128 raw or 118 raw+JPEG frames, but maximum burst speed is limited to 12 fps when shooting uncompressed raw. These numbers are similar to what the A9 managed in the lab.

If you're shooting an Alpha-mount lens on Sony's LA-EA3 adapter, performance is more limited than for E-mount optics, but still pretty swift at up to 10 frames per second. (See this Sony support page for the various continuous shooting and AF tracking capabilities, as performance heavily depends on the lens and adapter type.) And as if that wasn't already plenty, the Sony A9 is also capable of performing autofocus and autoexposure calculations a whopping 60 times per second!


It's not just performance that's generous, either; the Sony A9 also offers a very wide sensitivity range. By default, everything from ISO 100 to 51,200 equivalents with a mechanical shutter, or 100 to 25,600-equivalents with an electronic shutter. And if that's not enough, both ends of the range can be expanded if you're using the mechanical shutter to encompass everything from ISO 50 to 204,800 equivalents. The electronic shutter can also reach down to ISO 50 equivalent but remains capped at 25,600-equivalent at the upper end of the range.

For movie capture, sensitivity ranges from ISO 100 to 51,200-equivalents.


Like other A-series mirrorless bodies, the Sony A9 offers up the company's E-mount on which to mount lenses. Either full-frame FE or sub-frame E lenses are accepted, but if you use the latter then there's an unavoidable sensor crop which reduces the maximum resolution to just ten megapixels.

You can also use Sony's A-mount lenses courtesy of the LA-EA-series mount adaptors. And of course, a wide range of third-party lenses are available, or can be mounted on the Sony A9 courtesy of a variety of first and third-party adapters. (Note that many of these adapters will not allow for features like autofocus, autoexposure or stabilization, however.)


The Sony A9's autofocus system is impressively point-rich, with a total of 693 phase-detection autofocus points covering some 93% of the image area. The sheer number of points makes the A9's stunning 20 fps burst capture rate with AF adjustment between frames all the more impressive. And thanks to the availability of a touch-screen display with Touch Focus function, choosing from the huge selection of AF points should be as easy as the tap of a finger.

Of the 693 total points, 221 are also available with APS-C subframe lenses, and 299 are available with full-frame lenses and an APS-C crop active. There are also 25 contrast-detection AF points. The AF system has a working range of -3 to +20 EV at ISO 100 with an f/2.0 lens attached, and there's an AF assist illuminator with a range of 0.3 to 3 meters when shooting with the FE 28-70mm F3.5-5.6 OSS zoom lens mounted.

Face detection autofocus is also available, and is now said to offer 30% better eye detection thanks to more accurate face detection algorithms that can better deal with angled or partially-shaded faces.


The Sony A9 features a new in-body, sensor-shift type five-axis image stabilization system which Sony claims is capable of providing a five stop corrective strength. (That figure was determined using the Planar T* FE 50mm F1.4 ZA lens.)

Wondering what the five axes are? They're side-to-side roll around the central axis of the lens, as well as front-to-back tilt, left-to-right yaw and both vertical and horizontal translational motion.


As noted earlier, the Sony A9 includes dust and moisture-resistant seals in its design, but like almost any camera, dust can still make it into the body during lens changes or (depending on the lens design) while zooming or focusing.

To help handle that, Sony has applied an anti-static coating over the image sensor's cover glass to help prevent dust from adhering in the first place. Once dust particles do get stuck over the sensor, the A9 relies on its sensor shift mechanism to try and shake them free. Subjectively, we don't find sensor shift-based dust reduction systems to be as effective as those based around a piezoelectric element which can vibrate the sensor at much higher frequencies, but a sensor shift-based system is still preferable to none at all!


Sony is making a big deal about the viewfinder in its new Sony A9 camera, and for good reason: It's where one of the camera's most significant advantages over a DSLR can be found.

When shooting with a DSLR, there's a brief but noticeable interruption to the viewfinder image every time you trip the shutter, and at the precise moment of image capture, you can see nothing at all through it. If you want to be certain that you got the shot, you'll instead need to review it post-capture, perhaps missing the chance for another, even better image. But the Sony A9 avoids that concern, as it now has the performance to offer a totally blackout-free viewfinder image. You can see what you're framing, uninterrupted and close to real time at 60 frames per second during continuous burst capture when using the electronic shutter. A 120 frames per second refresh rate is available when not using the electronic shutter.

And the viewfinder is impressive for more than just its speed. It also has a very high 3,686,000-dot resolution from an Organic LED panel. That resolution equates to around 1,280 x 960 pixels in a 4:3-aspect, SXGA array (or Quad VGA), and it comes paired with a Zeiss T* coating to reduce reflections and improve contrast, as well as a fluorine coating on the outermost lens element to help prevent smudges, dust and dirt from adhering.

Magnification is 0.78x, as measured with a 50mm lens at infinity, and the viewpoint is 23mm from the eyepiece lens, or 18.5mm from the eyepiece frame. Sony rates its viewfinder at 100% coverage, and has provided five step brightness and color temperature controls to allow you to tune it to your tastes. (Brightness can also be adjusted automatically, should you prefer.)


When you're not using the viewfinder, you'll be interacting with the Sony A9 through its 2.95-inch, 1,440,000-dot rear-panel LCD monitor. It's mounted on a tilting articulation mechanism which allows it to be flipped upwards by some 107°, or downwards by around 41°.

And in a first for a Sony flagship camera, it comes accompanied by a touch-screen overlay which also allows the LCD to serve double-duty as an input device. It can't be used to control menus or interact with on-screen displays, though, only to select a subject on which to autofocus.


Not surprisingly for a camera aimed at pros, the Sony A9 doesn't include a built-in flash strobe. It does, however, provide the flash connectivity that Sony-friendly pros will be looking for: The company's proprietary Multi Interface Shoe (which can accept Sony Alpha strobes natively or be adapted to work with earlier Sony AAS / Minolta iISO strobes) and a standard PC sync terminal. Sony's P-TTL flash metering system is supported, with X-sync at 1/250 second. +/-3 EV of flash compensation is available in 1/3 or 1/2 EV steps. Wireless and high-speed sync modes are supported with compatible flash units.


The Sony A9 provides all of the exposure modes you'd expect to see in a pro-friendly camera, plus a few extras. There are, of course, Programmed Auto, Aperture-priority, Shutter-priority and Manual modes. There's also an Intelligent Auto mode, plus a Movie mode which itself allows Program, Aperture or Shutter-priority and Manual exposure, and a Slow & Quick Motion movie mode which provides the same four options.

Exposures are determined using the image sensor, and the scene is broken down into 1,200 zones by the evaluative metering system. Multi-segment, center-weighted, spot (with two size options), average and highlight metering options are available. There's also +/-5 EV of exposure compensation in 1/3 or 1/2 EV steps, although the physical exposure compensation dial can only function within a +/-3 EV range. The metering system has a working range of -3 to 20 EV at ISO 100 with an f/2.0 lens.

As mentioned previously, the Sony A9 has both a mechanical shutter, and an electronic shutter function with minimal rolling shutter effect. Shutter speeds with the physical shutter mechanism range from 1/8,000 to 30 seconds plus bulb, while the electronic shutter allows for vibration-free and silent shooting from 1/32,000 to 30 seconds plus bulb. The top 1/32,000 speed is only available in Shutter-priority or Manual exposure mode, though; other modes are limited to 1/16,000 second.


The Sony A9 doesn't just use its spectacular performance for still images. It's also capable of recording movies at up to Ultra High Definition 4K (3,840 x 2,160 pixel) resolution. Full-pixel readout is used across the entire sensor width, and there's no pixel binning, providing a 6K feed off the sensor at 24 frames per second, however there is about a 1.2x crop for 4K video at 30 frames per second. This is then downsampled at capture time to create a high-quality 4K output with a bit rate of up to 100 Mbps and a choice of XAVC S, AVCHD or MP4 compression types.

You can also record Full HD (1,920 x 1,080 pixel) footage at up to 120 frames per second, and HD (1,280 x 720 pixel) footage at a fixed 30 frames per second. And courtesy of the Slow & Quick Motion modes, you can record with frame rates from one to 120 frames per second in eight steps, allowing for anything from a 60x quick-motion effect to a 4x slow-motion effect while still providing a decent frame rate for your viewers.

All of this in itself isn't so different to what we've seen in other recent high-end Sony cameras, but the Sony A9 brings more to the table courtesy of its more powerful autofocus system, its touch-screen control for easy subject selection, and its in-camera five-axis image stabilization system. Sony says that the autofocus system has "nearly the same width" for movie capture as it does for stills, and notes that it can now caters to even slower focus transitions if desired. And rolling shutter is said to have been greatly reduced, too, something that should make the A9's videos much more suitable for quick-moving subjects.

Wireless communications

As is quickly becoming the norm even in interchangeable-lens cameras, the Sony A9 includes in-camera 2.4GHz 802.11b/g/n Wi-Fi wireless communications capability. This comes accompanied by both Bluetooth 4.1 and NFC radios, allowing not just for wireless transfer of images and remote control of the camera, but also for low-power geotagging based on information provided via Bluetooth from your smartphone, and easy pairing and sharing for Android users simply by bumping phone and camera together.

Wired connectivity

It's the wired connectivity which will really get the pros salivating, though. That's because Sony has included not only the usual array of Micro USB 2.0, Type-D HDMI, PC sync, microphone and headphone terminals, but also a 100Base-T Ethernet terminal for FTP file transfer. And even better, images can be encrypted and sent via FTPS connection, should you prefer.


The Sony A9 features dual card slots, each with its own specification. The lower slot of the two accepts only SD cards, and is compatible with the higher-capacity SDHC / SDXC types, as well as the higher-speed UHS-I and UHS-II types. The upper slot offers all of this except the UHS-II compatibility, instead providing only the rather slower UHS-I support, but if you're a Sony fan, you'll also be able to use your Memory Stick Duo cards in this slot.

Data can be copied between cards in-camera, and you have a choice of recording data to both slots simultaneously to provide a backup in case of card failure, or segregating file types so that stills are saved to one card and movies the other, or so that JPEGs are recorded to one card and raws to the other.

Two raw formats are on offer in addition to the default compressed JPEG file format. You can choose from either 14-bit uncompressed raws for maximum image quality, or compressed raws for a greater buffer depth. As mentioned previously, uncompressed raw can only be captured at up to 12 frames per second, and the effective bit depth drops to 12 bits in continuous mode regardless of frame rate or shutter type (confirmed with a production camera in the lab). There are three JPEG compression options: Extra Fine, Fine and Standard. You can, of course, also shoot both raw and JPEG formats at the same time, regardless of which raw file type you opt for, though like prior Sonys, JPEG quality is fixed to Fine when shooting raw+JPEG.


Sony has developed a new NP-FZ100 battery pack which makes its debut in the Sony A9. That's a bit of a double-edged sword if you're already a Sony shooter, as you won't be able to use your existing battery packs in this camera. What you will be able to do, though, is shoot a heck of a lot more content on each battery charge than in previous models, as the new battery provides 2.2 times as much capacity.

According to Sony, battery life should be on the order of 650 shots on a charge when using the LCD monitor, or 480 shots on a charge with the viewfinder, and that's to CIPA testing standards which mean there's a lot of switching the camera on and off, leaving it idle between shots, and so forth. In the real world, you'll very likely get many more shots on a charge, especially if you're rattling off lengthy bursts.

For movie capture, battery life is predicted to be on the order of 195 minutes with the LCD monitor, or 105 minutes with the viewfinder.

And if that's not enough, you'll be able to double all of these figures if you purchase the optionally-available VG-C3EM portrait / battery grip accessory, which can hold two batteries at once. Close to a thousand shots even when shooting through the viewfinder? Sign us up!

In-camera battery charging is supported and an AC-UUD12 AC/USB power adapter is included.


Editor's Picks