Face detection is on-hand in the Panasonic HDC-SD40, setting focus and exposure by using a human face within the frame as a reference point. This works in tandem with the Intelligent Auto (iA) system Panasonic has offered in its camcorders for a few years now. Essentially autoexposure on steroids, iA detects conditions and enables various scene modes, such as low light mode in poor illumination, or Portrait mode when nearby faces have been detected.
If you do want to control things more yourself, there are plenty of options too. However, the SD40 doesn't have a touchscreen, unlike the SD80. All settings are configured using a D-pad, menu and enter buttons on the side of the LCD. This unfortunately means there is no second set of buttons on the LCD edge for operating record or zoom, making two-handed shooting from the waist less ergonomic.
The menu button calls up the full settings menu, but the enter button is used to activate the shooting parameters, which vary in extent depending on whether you're in manual or Intelligent Auto mode. With the latter enabled, your only useful options are backlight compensation, tele macro, and PRE-REC, which continuously buffers video and tacks a few seconds extra on the front of your shot from before you hit the record button. That way, if your reflexes are a little slow, you won't miss the action.
As with virtually all Panasonic camcorders, bar its pocket Internet models, there's a full range of options in manual mode. Manual focus is available, although it's extremely hard to operate with the D-pad. White balance options include two presets each for indoor and outdoor conditions, as well as auto and manual modes. There are soft skin and intelligent contrast settings, the latter maximising detail in areas of shadow and brightness. There's also a colour night view option, which drops the frame rate right down below 1/25th, sacrificing motion smoothness for visibility.