Sony Alpha DSLR-A850 Performance, Timings, and Image Quality

PERFORMANCE
Given its 24 megapixel CMOS sensor and all the pixels this camera has to push, the Sony A850 delivers pretty good performance thanks, in part, to its dual Bionz processors. It's important to note, however, that compared to other less megapixel intensive DSLRs, the A850 is about average (or, in some cases, a little slower). If you have your heart set on a 24 megapixel, full-frame camera but want a more responsive camera, you may want to go for the Sony A900 instead.

Shooting Performance
The A850 is responsive in single shot mode with the lack of shutter lag one expects from a DSLR. Auto focus is a hair slower than we'd like, but it's not very noticeable unless you spend your life testing other cameras like we do.

Shutter Lag (press-to-capture, pre-focused)

AF Acquisition (press-to-capture, no pre-focus)

Continuous Shooting

*Note: Continuous shooting framerates are based on the camera's fastest full-resolution JPEG continuous shooting mode, using the fastest media type available (300x CF, SDHC, etc.). "Frames" notes the number of captures recorded per burst before the camera stops/slows to clear the buffer.

As noted earlier, the A850's continuous shooting speed is slower than the A900 (3fps vs. 5fps) so you may want to go with the A900 if you're shooting a lot of fast-moving action. In our lab tests, we managed to squeeze about 3.6 fps out of the camera but overall performance, including continuous shooting speed, is partly dependent on the type of media card used. Although the A850 has dual card slots, only one accommodates CompactFlash types I and II; the other holds a Memory Stick PRO Duo. For the best performance, you'll need a high speed CF card like the Lexar Professional UDMA 600x or the SanDisk Extreme IV.

Lens Performance
There are several options for outfitting the Sony A850 with a lens. Sony has been growing its own line of lenses with a nice range of zoom, prime and macro options. Granted, your dream lens-like the 300mm f/2.8 G-Series-may cost three times as much as the camera, but other lenses are less expensive. However, investing in a really good piece of glass is really important, even if you have to give up Starbucks or eating out for a while. While I have nothing against $300 lenses, you're just not going to get the best from any DSLR if you skimp on lenses.

Also keep in mind that if you use a Sony DT (digital lens designed for APS-C size sensors), it will crop the image of this full-frame camera to about 11 megapixels. You may also notice some vignetting as well. Most of my testing was done with Sony's gorgeous 24-70mm Carl Zeiss Vario-Sonnar f/2.8 lens. Yes, it cost almost as much as the camera body but is well worth it.

Sony has a lens guide on www.sonystyle.com that's useful when deciding on what lens(es) to buy.

Image Quality
With the right lens and the appropriate settings, the Sony A850 is capable of producing excellent images both on-screen and in print. Using the 24-70mm Carl Zeiss Vario-Sonnar f/2.8 lens, images were sharp and detail capture was quite good. With the huge files produced by the A850, it's also possible to crop images without losing anything in quality (depending on how tightly the image is cropped, of course).

Colors at the default setting were generally natural looking but well-saturated. With all the tweaking options available on the A850, it's easy to adjust saturation and other parameters to get images that not only suit the situation but that suit your taste and aesthetics.

Exposures were, for the most part, very accurate across a number of different lighting conditions. Using Sony's DRO (Dynamic Range Optimization) feature helped maintain details in shadows and highlights under high contrast conditions, although at lower levels, the changes were often difficult to discern. Overall, however, DRO is effective and does what it promises, albeit sometimes subtly. This feature can be turned off as well.

Auto white balance accuracy was a mixed bag. Images shot under incandescent light were very warm. Multiple WB options-with fine-tuning capabilities-are available, however, to more accurately capture images under different lighting conditions and it's best to use the manual WB controls for most shots.

Auto White Balance, 3200k incandescent light

The A850 offers native ISO from 200 to 3200, which can be expanded to ISO 100 and 6400. I was generally comfortable with the results up to about ISO 800 and would use ISO 1600 when necessary. Image quality (color rendition rather than image noise) degraded slightly at ISO 100.

ISO 100	ISO 100, 100% crop
ISO 200	ISO 200, 100% crop
ISO 400	ISO 400, 100% crop
ISO 800	ISO 800, 100% crop
ISO 1600	ISO 1600, 100% crop
ISO 3200	ISO 3200, 100% crop
ISO 6400	ISO 6400, 100% crop

Like the A900, however, the A850 can't quite live up to the low noise performance of its closest competitors such as the Canon 5D Mark II and the Nikon D700. For the most part, however, image noise wasn't bad, even up to ISO 1000. What surprised me most was the extreme image noise at ISO 6400.

Granted, I tend to keep in-camera Noise Reduction turned off in all DSLRs since I'd rather deal with image noise with software rather than let the camera compensate for higher ISOs. On one occasion, I set the ISO to 6400 for an indoor shoot and forgot to change it when I went outside to shoot a model. I ended up with images that looked good at small sizes but, when enlarged to 100% on the computer screen, revealed blotching on the model's skin that made the image unusable for anything other than the Web or small prints.

Since image noise is often more prominent on skin, noise was slightly less visible on other areas of the image (including the front of the model's dress). Best bet for shooting high ISOs on the A850? Turn off noise reduction, shoot RAW and deal with it in post-processing.

Additional Sample Images