Here I'll briefly review and recommend the Pentax W90 and Canon G12 for scientific work in the field and lab. Nobody’s paying me for this.
I've shot tens of thousands of photos with the predecessors of both cameras -- the Canon Pro1 and Pentax Optio.
The Pentax W90 (detailed review). Improved over the Optio, this camera is waterproof and ruggedized, with rubber armor all around. You can use it while digging into a streambank, with sand on your hands. And dip it into the creek to clean it. Controls are very intuitive and not at all fussy, something I demand for a basic field camera. There are other "weatherized" cameras, but Pentax pioneered this with the Optio and takes it seriously. I don't hesitate to put this camera under water. Image quality is very good in all the conditions in which I've used it.
Its macro capabilities are easy to use and perfect for scientific work -- it has a "1cm" macro setting you enable with two button presses for very detailed close ups and three small LEDs around the lens to illuminate these.
Canon G12 with flip out LCD
The Canon G12 (detailed review). There's something unsexy about a camera that whirs and pokes out a lens when you turn it on, but I've come to understand why this is a necessary evil. The Canon G series is widely used as a backup by photojournalists for a reason -- you can put it in a big pocket, but it performs like a digital SLR. And it puts controls you use most often in retro-35mm knobs on top. Practical, intuitive, fast, and cool.
You can't use this camera with sand on your hands, but otherwise it’s perfectly suited for serious science in the field and lab. With the lens retracted it's about the size of my big fist, and I can wrap that hand around it and shove it into its case without worrying about smudging the lens. Great for the field.
And has the Canon flip-out screen. You can hold it above your head or put it on the floor and rotate the LCD to view and frame your photos. I use this feature every time I use this camera and can't imagine being without it. Other companies are imitating it now, but Canon has it down.
Filters are essential for serious science photography. The G12 has a bayonet ring around the lens for accessories like a polarizing filter, essential for river scenes and aerial photography.
Canon sells filter adapters, but Lensmate has a new system that enables easy use of filters. With these adapters you have a camera that fits a cargo pocket along with sophisticated filter capability.
Lensmate also sells an adapter for use with telephoto and wide angle lenses.
The G12 shoots video that rivals that from our pro video cams. I’m now shooting most of our instructional video with it, see the example below. (Though the G12 has a very nice on-camera microphone, the sound in this video was dubbed later.)
A couple of weeks ago my new G12 was crushed by the rear door of a truck as we loaded an Em2 model. After minor surgery on our electronics bench it's bent, but works just fine! A very rugged camera!
My G12 was crushed by the huge rear door of an eighteen-wheeler. The frame was bent, but a little surgery freed up the jammed LCD and the camera works fine!
Taken with the G12 held overhead using the tilting LCD screen.
Both cameras have excellent macro capabilities.
The G12 does a wonderful job in low and mixed lighting. Here Lily and Meriam show off Lily's knitting handiwork in a combination of window sun and fluorescent light.