Sony Alpha DSLR-A900 Review

Timings & File Sizes

In use it's easy to forget just how much data the Alpha 900 is capturing and processing (up to 41 megabytes per shot), because it feels incredibly fast and responsive and rarely - if ever - gets in the way of your photography. The continuous shooting mode achieves a solid 5 frames per second in both JPEG and RAW, though you'll need to use a fast CompactFlash card if you really want to push the Alpha 900 (with slower CF cards or MS Duos the write speed is almost painfully slow when shooting extended burst sequences). Overall a very impressive performance.

Note that in all cases below the Dynamic Range (DRO) feature was set to Standard; using any of the advanced DRO settings increases the time taken to process each file (this has an impact on file write and record review times).

Timing Notes: All times calculated as an average of three operations. Unless otherwise stated all timings were made on a 6048 x 4032 JPEG Fine (approx. 6MB per image).

The media used for these tests were:

• 4 GB SanDisk Extreme Ducati Edition (UDMA) CF card
• 2 GB Lexar Pro 133x CF card
• 4GB Sony Memory Stick Duo

Media comparison

Continuous Drive mode

To test continuous drive mode the camera had the following settings: Manual Focus, ISO 200, Shutter Priority (1/2000 sec). Measurements were taken from audio recordings of the tests. Media used were the same as above.

The tests carried out below measured the following results for JPEG and RAW:

• Frame rate - Initial frame rate, this was always 5.0 fps (+/- 0.01 fps)
• Number of frames - Number of frames in a burst (until buffer full)
• Buffer full rate - Frame rate if shutter release held down after burst (buffer full)
• Write complete - How long after the last shot before the card access light goes out

Burst of JPEG Large/Fine images

Burst of JPEG Large/X.Fine images

Burst of RAW+JPEG (Large/Fine) images

Burst of RAW images

As I said at the top of the page, considering the huge files involved this is an impressive performance, especially using the UDMA SanDisk Ducati card. I wouldn't recommend using Memory Stick or slower CF cards if you want to shoot extended sequences.

File Flush Timing

Timings shown below are the time taken for the camera to process and "flush" the image out to the storage card. Timing was taken from the instant the shutter release was pressed to the time the storage card activity lamp beside the compartment door went out. Media used were the same as above.

As you can see there's quite a large performance differential between the SanDisk Ducati Edition and the Lexar Pro 133x and Memory Stick Duo (which comes in a distant third). That the Alpha 900 can process and write over 40MB of data to a fast CF card in around two seconds is nothing short of amazing.

USB transfer speed

To test the DSLR-A900's USB transfer speed we transferred approximately 500 MB of images (mixed RAW and JPEG) from a SanDisk Extreme IV Ducati Edition 4GB CF card.

Once again Sony proves that it is possible to produce a camera that offers high speed USB transfer (in Mass Storage mode it easily matches our dedicated card reader). Impressive stuff.