I bring my small camera along when my Canon 5DMkII would just be overkill. On cruises it's what I carry during a day devoted to shopping or an evening out in restaurants where I don't want to be encumbered with a lot of gear. I use it extensively in the confined space of a tour bus or small boat where there isn't the "swinging room" to pull out a larger camera. I also carry it discretely in places where an expensive DSLR might draw unwanted (and criminal) attention.
The Canon S90 (now replaced by the similar S95) has been with me for a number of years, and at 4" X 2" X 1", it goes a long way to addressing the small camera/big quality balance. It is a 10PM camera that is small and light enough to drop into a pocket yet has big camera features. It's 28-105 (35mm equivalent) lens is a fast f/2.0 at the wide end and a respectable f/4.9 at the telephoto end. In addition, the lens is also image stabilized which gives me even more of an edge at reducing camera shake.
The camera has several other features that I always look for - the ability to shoot RAW images and a usable histogram to review exposure information. RAW images tend to give a little more exposure latitude and allow for final processing under my control rather than relying on the camera to do the work. The histogram gives me a better indication of whether an image is properly exposed rather than relying on the inaccurate thumbnail that appears on the camera's LCD screen. For me, without these two features, a camera really is little more than a toy.
There is a full range of manual and semi-automatic controls, allowing for Aperture or Shutter priority, full manual, Program, Auto, and Custom as well as movie mode and eighteen - count them - eighteen special scene modes (including the ever popular aquarium mode). Also, when shooting JPGs, there are 10 white balance setting available to you.
The movie mode is only 640X480 @ 30fps (the current S95 has 780p HD movie mode) but it still turns in very acceptable movies that don't take up much room on the camera's memory card.
Probably the feature that is most useful on the S90 is the control ring around the front lens mount. This ring provides for easily accessed, customized control that just isn't found on many cameras. I can decide if the ring will remain with its default use, (which changes based on exposure mode) or for zoom control, white balance adjustment, exposure compensation or ISO selection. For those of us who grew up with analogue cameras, this is a great way to easily access one more set of controls that might otherwise be buried in a menu somewhere.
Are there any downsides to this camera? Sure, there isn't an optical viewfinder,and I don't believe that the most stable way to take a photograph is to hold your camera at arm's length from your face! The zoom range is also limited if you are doing anything more than general family, or holiday snaps. At 28mm it is wide enough for most needs but at the telephoto end, 105mm (equivalent) is only 2X magnification - hardly enough to bring in that whale if you are encountering wildlife in Alaska. For this, you are going to need something like the Canon SX30 with a telephoto reach of 840mm! While this camera costs not much more than the S95 does today, it is much larger.
The S90 has long been replaced by the S95 with only a few significant changes including the inclusion of 780P video and in-camera HDR capability. It too, is soon to be replaced by the S100 rumoured to have an increased 12MP sensor. With the S95 reaching end of life as of the summer of 2011, you might just find a great deal on a wonderfully small camera capable of delivering excellent results. If you are willing to deal with Fleabay, you ca find very nice S90's around the $200 mark.
Have your own favourite "digital derringer"? Share your camera of choice with us!