for most people working in an ED environment, wanting to use a camera for their own CME purposes, there are some general requirements which should be met:
small and light enough to take to work everyday
not too expensive that it becomes a big loss if stolen
we are NOT talking about status symbols here - ED professionals should not be needing these, if so, have a chat to your local ECATT regarding your insecurities in life.
if you must have a status symbol, buy a $40,000 Leica S2 and leave it locked up at home and just bring the bag to work.
relatively weather proof so that it can be wiped clean with antiseptic or water
no more than 10-12 megapixels (unless you will be aiming to produce a large format book)
THUS IGNORE HOW MANY PIXELS A CAMERA HAS, IN FACT MORE THAN 12MP MAY MEAN LESS IMAGE QUALITY!
a relatively wide aperture lens (eg. f/2.0 or f/2.8) - ie. NOT the kit lenses that come with the camera!
reasonable image noise performance at ISO 400 - most dSLRs can cope with this.
image stabiliser to minimise camera shake, particularly when using macro lenses
easy to use custom white balance for use in typical flourescent light environments
ability to use ISO 1600 or higher to allow shots of fluorescein-stained eyes illuminated by a slit lamp
focal length of lens allows images of A4 ECG or X-Ray to be taken at a reasonable distance eg. when ECG laid on bench and you are standing above it.
great quality jpegs straight from the camera without needing post-processing.
ability to set a lower resolution setting (eg. 1024×768 at mdeium compression) for immediate uploading to web-based usage without requiring time consuming post-processing to resize the image (in which case, it is nice if it will take a RAW shot and simultaneous separate low resolution jpeg.
silent mode to allow discrete photography during conferences as an aide memoire.
Panasonic GH-2 or G-3 is perhaps the most versatile compact camera available
Olympus E-PL3 is even more compact than the GH-2 or G-3 but doesnot have a built-in viewfinder although one can be added.
this exciting new digital camera system, primarily promoted by Panasonic is like a digital SLR in that it has a large sensor (same size as the Olympus Four Thirds cameras (eg. E-30) ) and thus higher image quality than compact cameras, and it can take interchangeable lenses (including Olympus Four Thirds via adapter and thus almost any other lens every made BUT only in manual focus), but it has several big advantages for doctors:
small, light and compact (although bigger than a Canon G10), and too big for a pocket
no mirror, so much quieter to use - better for conferences and meetings - although unless it has a electronic shutter it is not silent
adequate high ISO performance up to ISO 800-1600
compact Panasonic 20mm f/1.7 and Olympus 45mm f/1.8 lenses for indoor use
unfortunately at present, there is a lack of a nice 50mm f/2.0 macro lens which has compatibility for live AF (the Olympus macro lens will only allow manual focus with this camera), but I am sure such a lens will be on the drawing board and coming within the next 1-2 years.
Canon have a very nice range of digital SLRs, but generally are let down by their lens quality for cropped sensors.
unlike Olympus, they have not invested in a new range of pro quality high resolution lenses that are needed for a 10-15mp cropped camera or a 21mp full frame camera. Most of their pro (“L” class) lenses struggle to match 16mp on full frame cameras, particularly their zoom lenses.
furthermore, Canon has resisted putting an image stabiliser into the body of their cameras, and thus there is no image stabilised macro solution which is what we really need for clinically photography.
like Canon, Nikon still have not put an image stabiliser into their camera bodies.
unlike Canon, Nikon at least have an image stabilised macro lens, but unlike Canon and Olympus, they no longer make a ring flash which is a very useful flash in clinical photography when you don't want shadows (eg. photographing eyes or wounds close up).
the Nikon D700 combined with their top of the range ultra-wide angle zoom is perhaps the best ultrawide zoom combination on the market, but this strong point of Nikon is not really needed in the clinical photography world.
Nikon cameras to consider if you must go Nikon are:
Nikon D700 - full frame pro body - the way of the future for Nikon.
Nikon D300 - an excellent DX cropped format camera but consider buying full frame lenses for it rather than DX lenses.
Nikon D90 - a good entry level camera with very high image quality
consider getting the AF-S VR Micro-Nikkor 105mm f/2.8G ED-IF SWM:
unfortunately though, this lens is too long to be used comfortably for A4 ECG shots using a DX camera (D300 or D90), so it is best used with the full frame D700 if you wish to image ECG's and Xrays.
Relatively silent, pocket sized cameras
the current favorite is the Canon G9 or G10
the new Four Thirds Micro cameras with their sensor being 4x the size of a Canon G9, will offer much better image quality at ISO 400, and allow you to use interchangeable lenses, so keep an eye out for them.
eg. the Panasonic GH-2 - but too big for a pocket.