Because of the similarities between these two cameras and the fact that I reviewed them simultaneous, I decided to publish one review for both cameras rather than than two separate reviews with only minor changes in the text.
Sony A850 and A900 Key Differences
The differences between the A850 and A900 are so minor that it seems hard to justify the purchase of an A900 over the A850, given the $700 price discrepancy. The A850′s frame rate covers 3 fps, compared to 5 fps on the A900. Additionally, the A850 viewfinder coverage is 98% of the frame, compared to 100% coverage from the A900. Finally, the A900 includes a wireless remote, which is an excellent option; however, those who opt for the A850 can take some of that $700 they save to purchase the same remote for $30.
Auto-focus
The A850 and A900 have a great auto-focus system inside. You get 9 AF points, which can be selected by the user. The center AF point is center dual cross type for extra sensitivity. There are also 10 assist AF points.
The focus speed is quick and accurate on both cameras – even in low light. If you’ve read Photography Bay for a while, then you know that I like to use a single focus point, selecting individual points as necessary depending on the composition. Adjusting focus points is straightforward and easy with the joystick. As noted earlier though, if you like to change focus areas (e.g., Wide AF area, Spot AF area, etc.), then you’ll have to jump back to the quick menu.
My main gripe with the AF system is frame coverage. Nothing in this class of cameras stacks up to the frame coverage on the Nikon D700. While I’ll equate the speed of the AF system of the Sony cameras to the D700, the frame coverage and focus point options just don’t stack up for the A850 and A900. As a result, I end up with a lot of “focus and recompose” shooting.
Image Quality
With 24.6-megapixel, the A850 and A900 deliver in the resolution department. Files from the Alpha cameras are 6048 x 4032 pixels in size. With resolution like that, you can take advantage of the cropping space.The color reproduction is solid straight out of the camera. I really like the results from the A850 and A900 – in good light.
In lower light, if you bump the ISO speed, then you can get in trouble pretty quick. The 5D Mark II and D700 easily have a stop or two advantage over the A900 and A850. Shooting over ISO 1600 would be ill-advised for the Sony DSLRs.
Previously, I published an ISO comparison for the A850 and A900, along with the 5D Mark II and 7D. Below is a short sample taken from a 100% crop of the test scene.