Timing & Performance

The overall impression when using the DSC-F828 is that it is a very fast prosumer digital camera, thanks to a non-extending lens system the camera is ready to shoot in around 1.5 seconds, the mechanically linked zoom means that you can pick your zoom as quickly as you can turn the dial. The majority of operations are either very quick or virtually instant, especially switching the camera off and switching between record and play modes. Auto focus in good light was very fast and even in low light was respectable for a prosumer digital camera. As with the F717 the F828's storage interface is very fast delivering write speeds over 2 MB/sec (considerably better than most competitive prosumer digital cameras).

Two negative points are firstly the frustrating action of the shutter release button with or without auto review, if you press it slightly too quickly the camera simply ignores it, not good. Secondly the fact that RAW images are not buffered and you must wait over 10 seconds before you can take another shot in RAW mode. Other than that a very solid performance.

Timing Notes

All times calculated as an average of three operations (all cards formatted before testing). Unless otherwise stated all timings were made on a 8 MP / Fine JPEG image (approx. 3,500 KB).

Media used for these tests:

• 512 MB Lexar Pro 24x Type I Compact Flash card
• 1 GB SanDisk Ultra II Type I Compact Flash card
• 1 GB Sony Memory Stick Pro

Action	Details	Time, secs (Lexar)	Time, secs (SanDisk)	Time, secs (MS Pro)
Power: Off to Record	AF brackets appear	1.3	1.3	1.5
Power: Off to Play	Initial image displayed	2.6	2.4	2.5
Power: Record to Off	Feels instant	<0.1	<0.1	<0.1
Power: Play to Off	Feels instant	<0.1	<0.1	<0.1
Auto Review	Image displayed	1.1	1.1	1.0
Mode: Record to IR	Image displayed	0.6	0.5	0.5
Mode: Record to Play	Initial image displayed	0.1	0.1	0.1
Mode: Play to Record		0.1	0.1	0.1
Play: Magnify	To initial 2.0x view	0.4	0.4	0.4
Play: Thumbnail view	3 x 3 thumbnails	0.9	0.9	0.6

Lag Timing Definitions

Half-press Lag (0->S1) Many digital camera users prime the AF and AE systems on their camera by half-pressing the shutter release. This is the amount of time between a half-press of the shutter release and the camera indicating an auto focus & auto exposure lock on the LCD monitor / viewfinder (ready to shoot).	(Prime AF/AE)
Half to Full-press Lag (S1->S2) The amount of time it takes from a full depression of the shutter release button (assuming you have already primed the camera with a half-press) to the image being taken.	(Take shot, AF/AE primed)
Full-press Lag (0->S2) The amount of time it takes from a full depression of the shutter release button (without performing a half-press of the shutter release beforehand) to the image being taken. This is more representative of the use of the camera in a spur of the moment 'point and shoot' situation.	(Take shot, AF/AE not primed)

Continuous mode

The tables below show the results of our continuous shooting test, indicating the actual frame rate along with maximum number of frames and how long you would have to wait after taking the maximum number of frames before you could take another shot. Note that continuous shooting modes are not available for RAW or TIFF image formats. Media used for these tests was a 1 GB SanDisk Ultra II card.

The F828's two full frame continuous shooting modes, Speed Burst and Framing Burst are essentially the same other than Speed Burst doesn't provide a review of images shot, Framing Burst briefly displays each image after it is taken (hence it's slightly slower).

Speed Burst continuous mode

Framing Burst continuous mode

As you can see the F828 is limited by its buffer to seven frames no matter what the output image size. Considering the amount of data being moved around the 2.6 frames per second delivered in Speed Burst mode is actually fairly respectable.

File Write Time and Sizes

Timings shown below are the time taken for the camera to process and "flush" the image out to the storage card, the timer was started as soon as the shutter release was pressed and stopped when activity indicator LED beside the storage compartment stopped blinking. This means the timings also include the cameras processing time and as such are more representative of the actual time to "complete the task".

Media used for these tests:

• 512 MB Lexar Pro 24x Type I Compact Flash card
• 1 GB SanDisk Ultra II Type I Compact Flash card
• 1 GB Sony Memory Stick Pro

The F828's storage interface throughput is impressive, both for Compact Flash and Memory Stick. It consistently delivered a write throughput greater than 2 MB/sec, and peaked with RAW images on Memory Stick Pro at around 3 MB/sec. There was no appreciable gain using Memory Stick Pro for JPEG images. The biggest disappointment is that RAW and TIFF images are not buffered and processed 'in the background' and thus you must wait over 10 seconds between each RAW shot.

Approximate write throughput (RAW)

• 512 MB Lexar Pro 24x: 2.1 MB/sec
• 1 GB SanDisk Ultra II: 2.3 MB/sec
• 1 GB Memory Stick Pro: 3.2 MB/sec

Low Light Auto Focus

This test is designed to measure the minimum amount of light under which the camera can still focus. The focus target is our lens distortion test chart (shown here on the right), camera is positioned exactly 2 m (6.6 ft) away.

Light levels are gradually dropped until the camera can no longer focus. This is carried out at both wide angle and telephoto zoom positions (as more light reaches the focusing systems with a larger aperture).

This test target is the optimum type of subject for most "contrast detect" AF systems (as it has a vertical line at its center), you should consider the results below the best you could expect to achieve.

Light intensity (Lux) = 2.5 x 2^EV (@ ISO 100), 10.76391 Lux = 1 foot-candle (fc)

As you can see from the results above the F828 can happily focus in complete darkness thanks to its Hologram (laser pattern) AF assist system. Without AF assist the F828 still performed well managing to auto focus at both wide angle and telephoto in very low light. This is no doubt thanks to the large maximum aperture of the lens.

Battery life

We ran the camera through our new battery life test. This test is designed to be fair and comparative to each camera and battery type:

• Take 4 shots without flash
• Wait 2 minutes (50% of the time powering the camera off)
• Take 1 shot with flash
• Wait 1 minute
• Repeat

Batteries are fully discharged and recharged before the test and all cameras were reset to their factory default settings. Here are the results:

With its powerful 8.6 Wh Lithium-Ion battery the DSC-F828 lasted a hugely impressive five and a half hours in our battery test. That's an hour and a half longer than the camera it replaces (the DSC-F717) which uses the exact same battery pack. Kudos Sony.