Manual Control Options
The Canon SD850 IS has a so-called Manual mode, but there isn’t complete control over the shutter speed and aperture. There are some manual controls available; they are outlined in the paragraphs below.
Focus
Auto Focus (8.5)
The Canon SD850 IS’s through-the-lens auto focus system works exceptionally well. The camera has a default nine-point AiAF mode that displays green boxes on the LCD to show users where it is focusing. Users can also select a central single point to focus on within the Recording menu.
The addition of the new Digic III image processor brings with it trendy face detection technology. This is the point-and-shooter’s dream: to hold the camera up and take a picture knowing the faces in the picture will be fully in focus. The Canon SD850 IS can detect up to nine faces at a time. It judges the lighting on the faces and then adjusts the exposure accordingly, so faces should never be blown out or out of focus. Canon’s face detection system works exceptionally well, quickly recognizing faces and tracking them across the frame.
The SD850 normally focuses from 1.6 feet, but can get a bit closer at 0.79 inches in the Macro mode. The Macro mode can focus as far as 1.6 feet when the lens is zoomed out and 1.3 to1.6 feet when the lens is zoomed in. Macro mode is found by pushing the left side of the multi-selector. That’s where the Landscape Focus mode resides, too: it focuses from 3 meters.
The Canon SD850 IS’s auto focus system works quickly and effectively, and the addition of the face detection system will wow a few people, too.
Manual Focus (0.0)
This PowerShot digital camera is not equipped with manual focus.
ISO (8.0)
The new Digic III image processor doesn’t add any more sensitivity to the current ISO range. Canon cameras with the Digic II processor had the same 80-1600 range that is included on the SD850 IS. The camera also has Automatic and High ISO Auto modes.
A feature fairly new to the lineup is the auto ISO shift. This wasn’t included on the SD700 predecessor, but is found in the Recording menu of the SD850. This feature has a cool concept: when the picture is in danger of blurring because of exposure settings, the camera displays its camera shake icon to alert users to up the ISO to a point that will eliminate blur. Users can then do this by pushing the print button. The problem with this feature, however, is that it isn’t very intuitive. It can only be found in the menu, and must be turned on and off. In addition, there’s no explanation of it except for one obscure page of the owners’ manual. For those who can find it, it is pretty cool – although any jump in ISO will bring a jump in noise and drop in image quality.
See how the ISO affects dynamic range and noise in the testing/performance section of this review.
White Balance (7.75)
The Canon PowerShot SD850 IS’s white balance settings are located in the Function menu. This is wonderful because the background of this menu serves as a live preview, so users can see the Cloudy preset to find out if it looks better than the Day Light. The following settings are available: Auto, Day Light, Cloudy, Tungsten, Fluorescent, Fluorescent H, and Custom. The selection covers the basics but forgets a flash setting, although most cameras exclude it. The SD850 does have the most important white balance setting: custom. This can be set by framing something white in the small box superimposed on the center of the image and then pushing the menu button. There are on-screen directions for this. Users can also set the print button to measure the custom white 
balance; this is great for lighting situations that change quickly, such as when the sun is rising or lighting changes at a ballet recital.
Exposure (7.0)
The camera may have a “manual” mode, but it doesn’t allow full manual control over the exposure. The shutter speed can be set for long exposures, but the aperture is purely automated.
Like other digital cameras, the Canon PowerShot SD850 IS has a +/- 2 exposure compensation range adjustable in increments of a third. It is found in the Function menu. There is no live histogram, but there is one viewable in the Playback mode so users can check the exposure there.
Metering (7.5)
The Metering mode can be changed in the Function menu. Like most digital cameras, there are three choices: Evaluative, Center-Weighted Average, and Spot. The Evaluative is the camera’s default and most useful mode for most situations. It measures the exposure from many points throughout the frame. When the Face Detection mode is on, this mode measures all the points and then takes into account the brightness on the detected face to ensure proper exposure. When I tested this mode under standard fluorescent office lights, the preview seemed to breathe as lights flickered and the metering flashed. The Center-Weighted Average metering mode read the exposure only from the middle of the image, while Spot uses only one point in the middle. The SD850’s metering selection is typical, and the live previews in the menu are a nice treat.
Shutter Speed (4.0)
The Canon PowerShot SD850 IS has an automatic shutter speed range that covers 15-1/1600 second. In the Manual mode, there is a Long Shutter mode that allows users to manually select options 1 second or slower. This option is hard to find, though. It is available by pushing the menu button while viewing the exposure compensation range. At 1.3 seconds and slower, the camera’s noise reduction system automatically kicks in. The SD850’s mechanical and electronic shutter flips at a decent pace for a compact digital camera, although many cameras also include a faster 1/2000 second choice.
Aperture (0.0)
The 4x Canon zoom lens on the SD850 IS opens to a wide f/2.8 aperture when zoomed out. This is great, but it’s nothing we haven’t seen before. When zoomed to its 4x capacity, the aperture can only open as wide as f/5.5, which isn’t wide at all. Many cameras with similar lenses shrink to about f/4.5, so the SD850’s smaller aperture is disappointing. With not as much light coming in the lens when it is zoomed in, users will want to boost the ISO or turn on the flash – both options I’d rather avoid. The minimum aperture on the SD850 is f/8, which is typical.
