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
| Action | Time, secs (4 GB SanDisk CF) |
Time, secs (2 GB Lexar CF) |
Time, secs (4 GB Sony MS) |
|---|---|---|---|
| Power Off to On *1 | 0.4 | 0.4 | 0.4 |
| Power Off to Shot *2 | ~ 0.2 | ~ 0.2 | ~ 0.2 |
| Sleep to On | <0.1 | <0.1 | <0.1 |
| Power On to Off *3 | 1.1 | 1.1 | 1.1 |
| Record Review RAW *4 | 2.2 | 2.2 | 2.2 |
| Record Review JPEG Fine *4 | 1.0 | 1.8 | 1.8 |
| Play RAW | <0.5 | <0.5 | <0.5 |
| Play JPEG | <0.5 | <0.5 | <0.5 |
| Play Image to Image RAW | ~ 0.1 | ~ 0.1 | ~ 0.1 |
| Play Image to Image JPEG | ~ 0.1 | ~ 0.1 | ~ 0.1 |
| *1 | Time taken from the power switch being turned to the ON position and the control panel display appearing on the main LCD. |
| *2 | Although the A900 takes just under half a second to completely power up it is able to take a picture almost as soon as it's turned on (this test is performed by holding down the shutter release and turning the camera on). |
| *3 | Time taken for the camera to completely power down, it first carries out a 'sensor shake' clean and then continues to access the storage card for just over a second. |
| *4 | Time taken from the shutter release being pressed to the review image being displayed on the LCD monitor. Note that using DRO-Advanced increases these times by around 80% |
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
| Timing | 4 GB SanDisk Ducati Edition CF |
2 GB Lexar Pro 133x CF |
4GB Sony Memory Stick Duo |
|---|---|---|---|
| Frame rate | 5.0 fps | 5.0 fps | 5.0 fps |
| Number of frames | 175 | 170 | 81 |
| Buffer full rate | - | n/a (uneven) | n/a (uneven) |
| Write complete | n/a (immediate) | 46 sec | 94 sec |
Burst of JPEG Large/X.Fine images
| Timing | 4 GB SanDisk Ducati Edition CF |
2 GB Lexar Pro 133x CF |
4GB Sony Memory Stick Duo |
|---|---|---|---|
| Frame rate | 5.0 fps | 5.0 fps | 5.0 fps |
| Number of frames | 125 | 43 | 40 |
| Buffer full rate | n/a (uneven) | n/a (uneven) | - |
| Write complete | n/a (immediate) | 50 sec | 80 sec |
Burst of RAW+JPEG (Large/Fine) images
| Timing | 4 GB SanDisk Ducati Edition CF |
2 GB Lexar Pro 133x CF |
4GB Sony Memory Stick Duo |
|---|---|---|---|
| Frame rate | 5.0 fps | 5.0 fps | 5.0 fps |
| Number of frames | 11 | 11 | 11 |
| Buffer full rate | - | - | - |
| Write complete | 11 sec | 52 sec | 72 sec |
Burst of RAW images
| Timing | 4 GB SanDisk Ducati Edition CF |
2 GB Lexar Pro 133x CF |
4GB Sony Memory Stick Duo |
|---|---|---|---|
| Frame rate | 5.0 fps | 5.0 fps | 5.0 fps |
| Number of frames | 14 | 13 | 13 |
| Buffer full rate | 1.1 fps | - | - |
| Write complete | 11 sec | 52 sec | 71 sec |
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.
| Image type | Time, secs (4 GB SanDisk) |
Time, secs (2 GB Lexar) |
Time, secs (4 GB Sony) |
Approx. size |
|---|---|---|---|---|
| 6048 x 4032 RAW + JPEG F | 2.0 | 6.3 | 8.0 | 41.8 MB |
| 6048 x 4032 RAW | 1.9 | 5.4 | 6.3 | 35.8 MB |
| 6048 x 4032 cRAW | 1.3 | 4.0 | 5.0 | 24 MB |
| 6048 x 4032 JPEG X.Fine | 1.3 | 2.8 | 3.3 | 13.7 MB |
| 6048 x 4032 JPEG Fine | 1.2 | 1.6 | 2.1 | 6.0 MB |
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.
| Method | Transfer rate |
|---|---|
| Sony DSLR-A900 (PTP device) | 13.9 MB/sec |
| SanDisk Extreme IV USB 2.0 card reader | 16 MB/sec |
| Sony DSLR-A900 (Mass storage device) | 17 MB/sec |
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.
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