Timings & File Sizes

The PowerShot S400 feels quick in use and never introduces significant delays to the user. Power On time is impressive consider the extending lens system, although there is an additional 0.7 seconds before the camera recognizes the power button press. Other operational performance such as menu navigation, FUNC menu settings changes and image magnification feel virtually instant. One nag however could be the image to image delay browsing in playback mode. The additional delay in AF Lag introduced by using AiAF should be noted, the camera does feel faster with AiAF disabled (center area AF only).

Timing Notes: All times calculated as an average of three operations. Unless otherwise stated all timings were made on a 2272 x 1704 Super-Fine JPEG image (approx. 1,600 KB per image). The media used for these tests was a 512 MB Viking CF card. Timings below with AiAF switched off (faster) unless otherwise noted.

Action	Details	Time, seconds
Power: Off to Record *1	Lens extension	2.1
Power: Off to Play	Image displayed	2.4
Power: Record to Off	Lens extended	2.3
Power: Play to Off	Lens already retracted	0.8
Mode: Record to Play *2	Image displayed	2.5
Mode: Play to Record	Lens extended	1.9
Play: Magnify	To 10x magnification	1.0
Play: Thumbnail view		1.1

Action	Details	Time, seconds
Zoom from Wide to Tele	Full zoom from 35 mm to 105 mm (3 x)	1.8
Auto Focus LAG	Wide angle	0.7 - 1.0
Auto Focus LAG	Telephoto	1.0 - 1.2
Auto Focus LAG	Wide angle, AiAF On	0.9 - 1.1
Auto Focus LAG	Telephoto, AiAF On	1.1 - 1.4
Shutter Release LAG	Using Viewfinder	<0.1
Shutter Release LAG	Using LCD Monitor	0.1
Total LAG	Wide angle	0.8
Total LAG	Telephoto	1.5
Off to Shot Taken	Wide angle	3.5
Shot to Shot	Wide angle	1.5

Auto Focus LAG is (roughly) the amount of time it takes the camera to autofocus (a half-press and hold of the shutter release button), this timing is normally the most variable as its affected by the subject matter, current focus position, still or moving subject etc. This timing is an average.

Shutter Release LAG is the amount of time it takes to take the shot from the moment you fully depress the shutter release button, measured both as a time including auto focus and a time assuming you have already pre-focused by holding a half-press of the shutter release.

Continuous modes

Just like the S45 the S400 has two different continuous drive modes. The first (Continuous) shoots at approximately 1.5 fps and displays each frame on the LCD monitor as it is taken. The second (Continuous H) shoots at approximately 2.5 fps but blanks out the LCD monitor while shooting.

The table below shows 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. The media used for these tests was a 512 MB Viking CF card.

The S400 delivers good continuous shooting capability with an obviously fair sized buffer. Overall a very good performance for the class of camera.

File Write / Display and Sizes

Timings shown below are the time taken for the camera to process and "flush" the image out to the CF card, the timer was started as soon as the shutter release was pressed and stopped when activity indicator LED beside the viewfinder 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". The media used for these tests was a 512 MB Viking CF card.

Fairly fast write times considering the file size and the product category. The camera also has a good buffer system which allows you to get on with taking the next shot while it continues to process / write the last shot in the background.

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)

The S400 produce a virtually identical performance with or without its AF assist lamp, this could be due to the fact that at least on our camera the AF assist lamp did not hit the center of the target, rather it was aligned lower than the center area of the scene frame.

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:

The PowerShot S400 managed to last 30 minutes longer than the S330 using the same 2.5 Wh NP-1LH battery pack. This is a good performance for such a small, relatively low capacity battery. Clearly Canon's claims about power savings with their DiGiC processor are accurate.