Sony Alpha A850 Review
by Bob Atkins, January 2010 (updated February 2011)
The Sony Alpha A850 is essentially the same camera as the Alpha A900, with a few less features and a significantly lower price tag ($2000 vs. $2700 as of March 2010). It has identical specifications to the A900 (including the same 24.6MP sensor) except for two things. First, the viewfinder has 98% coverage (the A900 has 100% coverage). Second, the maximum continuous shooting rate is 3 frames per second (fps) (the A900 is 5 fps). Otherwise, the cameras appear to be identical. Note that neither the A850 nor the A900 has the Live View and Video modes, which seem to be becoming standard on most new DSLRs these days.
At $2000, the A850 is the lowest cost full frame DSLR currently available. The nearest competitors are Sony’s own 24.6MP Sony Alpha A900 (review), at a list price of $2700, the 12MP Nikon D700 (review), which at the moment is selling for around $2400, and the 21.1MP Canon EOS 5D Mark II (review), also at $2700.
Compared with the Nikon D700, the Sony A850 has double the pixel count, which for some may be an important factor. The pixel count of the EOS 5D MkII is, for all practical purposes, the same as that of the A850. However, for the extra $700 you do get full HD video capability and higher ISO settings (ISO 25600 vs. ISO 6400) with the Canon EOS 5D MkII. Tests of the Alpha A900 showed that its noise performance at higher ISO settings wasn’t quite up to that of the Nikon D700 and EOS 5D MkII, and since the A850 uses the same sensor as the A900, it’s not unexpected that it will show similar performance.
One feature that the Sony Alpha A850 has, which Nikon and Canon DSLRs don’t have is built-in image stabilization (IS) via a sensor shift system. Sony claims that their built-in IS is good for up to 4 stops of additional stability, meaning that you should be able to handhold the camera with a 50mm lens at shutter speeds as low as around 1/6s. Canon and Nikon can do similarly using their image stabilized lenses, but of course not all Nikon and Canon lenses are available in stabilized versions.
Camera Controls
Bob Atkins
The control layout of the Sony A850 is relatively conventional. On the top deck there is a mode control dial on the left with positions for manual, shutter priority, aperture priority, program and full auto modes. There are also three user programmable custom modes (1, 2 and 3). There are no “scene” modes. On the right of the top deck are buttons for white balance, ISO setting, exposure compensation and drive mode. There is a diopter correction adjustment on the right side of the viewfinder.
On the top deck of the camera there’s a small LCD, which normally shows battery status, estimated shots remaining, aperture, shutter speed and whether exposure compensation is in use. It can also be used when changing WB, Drive mode and ISO setting. The WB settings are spelled out (albeit using some rather odd looking characters!) rather the the tiny icons found on some other DSLRs, which makes them easier to see. Similarly the drive mode settings on the top LCD are rather cryptic abbreviations. However, both WB and Drive modes are also displayed on the rear LCD when changing settings and are somewhat easier to read there since they are spelled out in detail. There is a button to illuminate the top LCD display immediately to the right of the LCD.
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On the back of the camera the on/off switch is at the top right, just to the left of the viewfinder. To the left of the LCD are buttons (top to bottom) for displaying the menus, changing the display data and format, erasing images and playback. At the lower right is the switch, which tuns the “steady shot” (sensor based image stabilization) on and off, plus “C” and “Fn” buttons. The “C” button allows setting of the “creative style” by default but can be reprogrammed to activate almost any of the control menus such as flash compensation, AF lock, WB, ISO setting etc. The “Fn” button brings up the quick navigation screen which allows any of the displayed camera parameters to be changed.
At the upper right is a 4-way controller with a center “set” button which can be used to navigate through menus and make selections. Above that is a rotary switch to select metering mode with a center button which engages exposure lock. Next to the AE (auto exposure) lock is a button, which allows quick switching between auto focus (AF) and manual focus (MF). In AF mode it enables MF and in MF mode it enables AF.
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There’s also a second control dial at the upper right of the back which acts like the rear QCD (Quick Control Dial) on EOS DSLRs. Basically it’s a control dial, which can be operated using your thumb while the main control dial is operated using your forefinger. Both can be used to set shutter speed and aperture and the rear dial can be customized for other functions, for example setting exposure compensation.
Focus mode can be set via a multi position switch on the front of the camera at the right of the lens mount. Settings are MF (manual focus), C (continuous tracking AF), A (auto mode selection) and S (single “one shot” AF). On the left of the lens mount is the DOF (depth of field) preview button.
Buffer and Timing
Using a SanDisk 16GB Extreme Pro CF card, which is rated at 90MB/s and is UDMA 6 compatible, Shooting in manual focus mode, ISO 400 with a shutter speed of around 1/500s at f/2.8 and with D-RangeOptimizer off and high ISO NR set to normal I obtained the data listed below. Note that the Alpha A850 is UDMA mode 5 compliant, so should be able to operate at maximum speed with a UDMA mode 6 card (which is even faster than mode 5). UDMA 5 supports data transfer speeds up to 100MB/s while UDMA 6 can theoretically support data transfer at up to 133 MB/s
In RAW mode the buffer held 18 frames shot at a rate of 3.0 frames per second (fps). When the buffer filled the frame rate dropped to 1.35 fps.
In RAW+JPEG mode the buffer held 14 frames shot at a rate of 3.0 fps. When the buffer filled, the frame rate dropped to 1.19 fps.
In JPEG (extra fine) mode I gave up on trying to fill the buffer after 110 shots! The frame rate was the same as shooting in the other modes, i.e. 3.0 frames/sec.
The buffer sizes measured are significantly better than those quoted by Sony in the Alpha A850 manual, which quotes 16 images in RAW mode, 12 images in RAW+JPEG mode and only 34 images in JPEG (extra fine) mode. However, Sony doesn’t say which CF card was used to obtain their test numbers and what the speed of that card was. The SanDisk card used in these tests is one of the fastest CF cards currently available.
With a Sandisk Extreme III card (rated at 30MB/s), the buffer held 15 RAW files (At 3 fps) after which the frame rate dropped to 0.82 fps). In RAW+JPEG mode 12 frames filled the buffer after which the frame rate dropped to 0.66 fps. In JPEG (extra fine) mode the buffer held 68 frames at 3 fps before slowing down and shooting bursts of 6 or 7 frames at 3 fps with 1.6 second pauses between the bursts.
It’s clear that the Sony Alpha A850 can take advantage of faster CF cards, which provide a larger buffer and faster frame rate after the buffer fills. If you never shoot bursts long enough to fill the buffer, the maximum frame rate of 3 fps does not require use of the fastest cards.
ISO and Image Noise
Bob Atkins
The Sony Alpha A850 has an ISO range of 200-3200, which can be expanded to include ISO 100 and 6400. The lowest “native” ISO is 200. As you would expect, noise is pretty much a non-issue at the lower ISO settings. At ISO 400 it’s visible, but still not really of any concern. ISO 800 and 1600 show more, but still generally acceptable noise. At ISO 3200 and 6400 noise will likely be an issue in larger prints.
Though it’s hard to do direct comparisons due to differences in image processing and noise reduction algorithms, I’d say the Alpha A850 probably lags about a stop behind the EOS 5D MkII in terms of image noise at higher ISO settings and at least that far behind the Nikon D700 (which is a little better than the 5D MkII).
Of course you have to put this in perspective. If you don’t shoot for large prints at higher ISO settings then the noise level of the A850 won’t be an issue. A850 noise is no worse than that of a camera like the EOS 50D and being full frame, prints will look better.
Autofocus
Bob Atkins
The Sony Alpha A850 uses the same AF system as the a900. There are 9 primary AF zones with 10 supplemental zones. The supplemental zones are used to improve the AF system performance in wide area AF mode. The center AF zone is a dual axis cross sensor.
Once calibrated the AF proved to be fast and accurate. I say “once calibrated” because my initial tests with the Sony Zeiss 16-35/2.8 (see below) indicated that AF was slightly missing best focus. The Sony A850 has microfocus adjustment, which allows the focus to be adjusted by +/- 20 units (I’m not sure what the units correspond to in actual physical terms). Experimenting by comparing image sharpness as microfocus adjustment was changed, I found that a setting of -10 was required for best focus with this lens. After that, focus was accurate and reliable. The A850 allows one microfocus setting for each Sony lens, and it can recognize which lens is attached to the camera and apply the correction, which has been set. Since I only had one lens for this review I can’t say if the required adjustment is due to the lens or the body, but the microfocus adjustment function was certainly very useful in this case.
Viewfinder and metering
One of the few differences between the Sony Alpha A850 and A900 is that the A850 viewfinder “only” has 98% coverage, while the A900 has 100% coverage. To some this may be a big deal, but not to me. 100% is nice, but 98% is just fine too. Viewfinder magnification is 0.74x, pretty typical for a camera in this class.
Metering can be switched between Spot, Center Weighted and Multi-segment via a switch located on the rear of the camera. In multi-segment mode the camera looks at 40 hexagonal segments and uses internal algorithms to derive what it determines to be the best exposure. Center weighted mode gives greater weight to the metering segments around the center of the image and Spot mode uses only the center segment. Sony does not specify the angular coverage in spot metering mode.
SteadyShot
Image stabilization is achieved with the Sony Alpha A850 via Sony’s “SteadyShot” system. In contrast to Canon and Nikon systems, which use optically stabilized lenses, the SteadyShot system uses a moving sensor to compensate for camera movement. At the time of writing only Sony offers a full frame cameras with sensor based stabilization, although Pentax and Olympus use it on their crop sensor cameras.
Measuring the effectiveness of stabilization is difficult, since blurring due to camera movement is something of a statistical process. The slower the shutter speed the greater the chance of image blurring, though it’s still possible to get blurred images at fast shutter speeds and sharp images at low shutter speeds. There’s really no standardized test for stabilization effectiveness.
The only lens available was the Sony Zeiss 16-35/2.8, so all tests were done with this lens set to 35mm. Conventional wisdom suggests that you need a speed of 1/focal-length for a high probability of sharp images, so my first test was done at 1/40s and with SteadyShot turned off. I took 10-20 images at each shutter speed. I’d define sharp as no real obvious blurring looking at the image at 100%. Acceptable is slight blurring which probably wouldn’t be noticeable in small prints. Blurred is obvious smearing of detail.
At 1/40s with Steadyshot off, I averaged about 50% sharp images, 30% acceptable images and 20% blurred images. This is pretty consistent with what I’d expect based on previous tests. Some people may have steadier hands than I do and some may be shakier of course.
At 1/10s with SteadyShot on (2 stops slower) I averaged about 60% sharp images, 20% acceptable images and 20% blurred images. This suggests that I’m getting at least 2 stops of stabilization, maybe a little more. With steadyshot off, at 1/10s I got 80% blurred images and 20% acceptable.
At 1/5s with SteadyShot on, 70% of the images were blurred and 30% were acceptable. With SteadyShot off, 100% of the images were blurred.
So overall I’d say that, with a 35mm focal length lens, I was seeing slightly over two stops of additional stability from the SteadyShot system. This is probably slightly less then I’d expect to see from the best Canon and Nikon stabilized lenses. However, remember that the Sony system stabilizes the image with any lens mounted on the camera, not just stabilized lenses. For example that means you get a stabilized image with Sony 28mm and 50mm prime lenses, something that neither Canon nor Nikon can currently match.
Sony HVL-F58AM Flash
Bob Atkins
Like most (in fact all) full frame DSLRs, the Sony Alpha A850 doesn’t have a built in flash, so an external unit must be used. Sony’s top of the line flash is the Sony HVL-F58AM Flash, (compare prices), which has a guide number of 58 at 105mm and ISO 100.
The HVL-F58AM features the Sony Quick Shift Bounce system, which allows
the flash head to pivot 90 degrees left and right on a horizontal axis in addition to the conventional up and down vertical adjustment (see image on right). With this system, the camera and flash unit can keep the same orientation regardless of portrait or landscape shooting. The flash head also tilts from 10° down to 150° back.
The HVL-F58AM flash can control the ratio of lighting from several off-camera flash units. Up to three groups of flashes can be set up via a wireless connection. Flash output ratios can be adjusted and you can fire a modeling flash to preview flash effects before taking the picture. With multiple units, the modeling flash fires according to the flash ratios you set.
The HVL-F58AM has an advanced white balance compensation system that gathers color temperature information, complimenting the white balance information reading of the camera. This achieves more accurate results when the main unit is in auto white balance mode.
When used on a crop sensor camera, the HVL-F58AM can adjust its zoom setting to provide optimum illumination across the frame.
Sony’s ADI (Advanced Distance Integration) metering enables the HVL-F58AM to work more effectively with lenses equipped with distance encoders—combining TTL (through-the-lens) flash metering with guide number control calculated automatically according to the distance to the subject, the ambient light and the pre-flash reflectivity of the subject.
The HVL-F58AM also has a slide-out bounce sheet built into the flash head, and can be used for portraits using bounce flash to add a catch-light to the subjects eyes.
Sony SAL-1635Z 16-35mm f/2.8 ZA SSM Carl Zeiss Vario-Sonnar T*
Bob Atkins
The Sony 16-35mm f/2.8 ZA SSM Vario-Sonnar T Carl Zeiss, (compare prices) is one of the premium lenses in Sony’s lineup. It’s a fairly large and heavy lens (83×114mm, 860g) since it uses large diameter optics (77mm filter size) and extensive use of metal parts. Optically the design uses 17 elements in 13 groups with one ED, one Super ED and three aspherical lenses. Both zooming and focus are internal, so the lens does not extend when zoomed or focused. A 9 blade circular iris is used for smooth blurring on out of focus areas. Maximum magnification is a class leading 0.24×. Auto focus is fast and silent due to the “Super Sonic wave Motor” (SSM), which uses a similar technology to that in Canon’s USM and Nikon’s Silent Wave Motor. Full time manual focus is available, though there is an AF/MF switch if fully manual focus is desired.
Bob Atkins
As expected from a lens in this class (and price range), performance is very good and center sharpness is excellent, even wide open. Overall, the lens is weakest at the widest 16mm settings where the corners can be a little soft, some distortion is visible and there is reasonably intense chromatic aberration at the edges of the image. Corner image quality improves as the lens is stopped down to around f/11. Vignetting is also seen when wide open at all focal lengths. At 16mm the corners are about 2 stops down on the center, at longer focal lengths the effect is smaller.
Overall best performance is probably in the middle focal length range (around 24mm), but it’s no slouch at any focal length or aperture. However, the Zeiss name does not convey absolute perfection as some may wish or assume. It’s a very good lens, but it has issues, as any reasonable photographer would expect in a fast wideangle zoom.
Alternatives
At a list price of $1999, the Sony Alpha A850 (review) is the lowest price full frame DSLR available at the time or writing (early 2010). The Canon EOS 5D MkII, Nikon D700 and Sony’s own Alpha A900 are the closest competition, but they are all around $700 more expensive. The A850 (along with the A900) also has the highest pixel count at 24MP. That’s a little more than the 21MP EOS 5D MkII and double the 12MP of the Nikon D700. Clearly the Sony is leader of the pack in terms of pixels per dollar!
The Sony Alpha A900, (compare prices) (review) adds a 100% viewfinder (the a850 id 98%) and a continuous shooting rate of 5 fps (the A850 is 3 fps), but otherwise is just about identical to the a850 in terms of features and specifications.
The Nikon D700, (compare prices) (review) features outstanding performance at high ISO settings, which it gets by reducing the pixel count to 12MP and because it’s using larger pixels, ISO settings up to 25600 are available. The D700 has a frame rate of 5 fps, which can be boosted to 8 fps when using the MB-D10 multi-battery power grip.
The Canon EOS 5D Mark II, (compare prices) (review) Canon EOS 5D MkII has almost the same pixel count as the A850 (21MP vs 24MP) but adds a number of features including 1080 HD video capability, 5 fps continuous shooting and ISO settings up to 25600.
Conclusion
Overall, the Sony Alpha A850 is a very capable camera capable of yielding very high quality images, especially at lower ISO settings. The frame rate may be a little low at 3 fps and the buffer size may be smaller than some of the competition, but many photographers don’t need either high frame rates or large image buffers. The A850 lacks the video capability. Live View and extended ISO range of the EOS 5D MkII and the outstanding high ISO performance and high ISO settings of the Nikon D700, but again these are features not everyone wants or needs (or can afford).
The body based image stabilization of the a850 is a real advantage for anyone who likes to shoot wide to normal prime lenses in low light. Neither Nikon nor Canon offer any image stabilized wide or normal primes. With at least two stops of stabilization, the a850 negates most of the low noise advantage of the competition in these circumstances (as long as the subject isn’t moving).
Where to Buy
Photo.net’s partners have the Sony Alpha A850, (compare prices) (review)available for purchase. Their prices are fair and you help to support photo.net.
More Information
Image Samples
Bob Atkins
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Sony Zeiss 16-35/2.8 at 35mm. 1/40s @ f/2.8, ISO 500. Metering and white balance set to automatic. Geometric distortion (barrel/pincushion) is minimal at the 35mm setting |
Bob Atkins
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Sony Zeiss 16-35/2.8 at 16mm, 1/30s @ f/2.8, ISO 800. Indoor shot at 16mm. You can see very slight barrel distortion. The “keystoning” (converging verticals) are not lens distortion but are the result of the camera being tilted slightly upward. |
Bob Atkins
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Sony Zeiss 16-35/2.8 at 30mm. 1/4s @ f/9, ISO 6400. This was shot handheld at 1/4s with “SteadyShot” turned on. The image is quite sharp, even at 100% viewing, so SteadyShot is certainly helping. The multi-segment metering and auto white balance did a good job with this interior shot in difficult lighting |
Bob Atkins
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Sony Zeiss 16-35/2.8 at 35mm 1/250s @ f/9, ISO 200. Outdoor shot in bright sunlight. Automatic metering and white balance. |
Bob Atkins
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Sony Zeiss 16-35/2.8 at 35mm. 1/40s @ f/2.8, ISO 200. Automatic metering did a good job with this “atmospheric” shot, taking its main metering information from the light. |
Text and photos © 2011 Bob Atkins.
Article revised February 2011.
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, March 08, 2010; 08:27 P.M. 
