Sony A900 Performance

The A900's timing performance is about average for a semi-pro SLR.

Startup and shut-down times are quite fast, difficult to measure. Buffer clearing time depends on the image size and quality, burst length and the speed of memory card used.

Mode switching is reasonably fast, except for Record to Play, which is notably slower than average. (Slow enough to be an annoyance; this bothered us a fair bit as we shot with our test sample.)

In terms of the A900's ability to determine that it's properly focused when shooting the same target multiple times, its speed is about average for a semi-pro SLR. The A900 required about 0.183 second for full AF. Continuous autofocus mode lag time was about the same at 0.181 second, and manual focus was slightly faster at about 0.153 second. When prefocused, shutter lag dropped to 0.072 second. This is slightly faster than Sony's consumer SLRs, but slightly slower than some competing prosumer models.

Single-shot cycle time performance is also about average for a semi-pro SLR, at about 0.4 second between shots in large/extra fine JPEG quality or RAW mode. Buffer depth is quite good (particularly for a camera with such exceptional resolution) at over 20 frames for JPEGs and 15 frames for RAW. Continuous mode is also about average among high-end prosumer SLR models at 5 frames per second in all modes, with good buffer depth at 11 frames for large/extra fine JPEGs and 13 for RAW files. (Remember, though, that these are very large, 25-megapixel files, and our test target when doing timing is designed to be difficult to compress to deliver results from a worst-case scenario.)

Switching to APS-C crop mode did not improve cycle-time or burst rate, which implies the sensor interface is the bottleneck, but it did improve burst length and/or buffer clearing time.

Download speeds were extremely quick, fast enough that you probably won't feel the need for a separate card reader, even with the A900's huge files. (Note that this test was performed with a SanDisk Extreme III CF card: Slower cards would likely show slower transfer times.)

Battery

Good battery life for a full-frame DSLR.

The Sony A900 uses a custom rechargeable lithium-ion battery pack for power, and comes with both a single battery and charger. The rated 880 shots per charge is above average for an SLR, but don't forget, the A900 does not have a built-in flash which is normally fired for 50% of the shots during CIPA standard testing. We recommend getting a second battery and/or the optional battery grip for extended outings.

The table above shows the number of shots the camera is capable of on fully-charged battery, based on CIPA battery-life and/or manufacturer standard test conditions.

(Interested readers can find an English translation of the CIPA DC-002 standards document here. (180K PDF document))

Storage

The Sony A900 stores its photos on CompactFlash or Memory Stick Duo memory cards, and no card is included with the camera. The chart below shows approximately how many images can be stored on a 2GB card at each size/quality setting.

We strongly recommend buying a fast, high-capacity CompactFlash or Memory Stick Pro Duo card. The A900's files are huge, so you should probably consider at least a 4GB card, if not an 8GB one, to give yourself extra space for extended outings, especially if you plan on doing a lot of RAW shooting. (Check the shopping link above, cards are cheap these days, so there's no reason to skimp -- But do consider faster cards for this camera, to reduce buffer clearing times.)