Black & White Digital Photography

No such thing as a black and white digital camera.
All the sensors are designed to give you full colour.
I'm actually glossing over some of the finer technical points of exactly how the sensor in the camera works but basically just take it as read that the camera is colour only.

It is exceptionally easy to convert a colour picture to black and white in your computer though.
All you need is some clever software like Photoshop if you have loads of money to burn.
Or you can use something that's 99% as good and is completely free :

http://www.gimp.org/windows/

This really is a very good image processing package that does everything you will ever need it to do.
And it's free.
Plus the user manual is very easy for a beginner to understand.

Sorry, but I have to disagree with Heliotrope.

Many digital cameras have built in settings to change to black & white or even sepia. i.e. the Panasonic TZ1 is one of these.

So how does that make the camera a black and white one ?

It may have a black and white mode but that is accomplished by discarding the colour data from the sensor exactly the same way as you'd do it in Photoshop.

No such thing as a black and white digital camera.

As a professional photographer and former photo products retail sales rep, I'd agree that there's no such thing as a B&W digital camera. however, this is a matter of semantics. Yes, the camera can produce B&W images. How it does this is irrelevant to the spirit of the question.

There are some digital cameras that have software interfaces that allow you to use B&W mode. Some have better interfaces than others.

As a general rule, I prefer Canon, Nikon and Olympus's interfaces for this function over others.

Also, please know that with some inexpensive (or free) imaging software, you can convert downloaded image files to B&W with decent quality and no need for expertise.

My understanding of this comes from my understanding of science, and of software (i.e. this is nothing more than somewhat educated conjecture).

For a black and white photo, you are dealing with light and darkness that may not exactly map to colors. I am sure that the number of shades of gray matter. I would also imagine that you might also be concerned about how the brightness of each color mapped to the shade that was chosen.

I do know that good software (for example The Gimp) can let you choose to brighten some colors over others.

Ragman... perhaps you could put my ideas into photographic terms (or tell me I am way off base).

I would guess that some cameras support a greater range of brightness. I would also imagine that there might be some difference in how different cameras record the brightness of different colors.

Yes...correct...Tonality issues as far as B&W matters and program's interpretation of values and thresholds, varies.

Now, that being said, that issue also relates to histograms (math ... logarithms ... curves ... etc) and density...light and dark areas ..making for drama and not producing a flat looking image. Because many times if you strip (desaturate) all the color info from a color image, you will end up with a low contrast, dull resultant image.

How a digicam's software interpolates and dithers the pixels (color data bits) info and converts that into brightness and contrast will vary from program to program.

All of which can be repaired or adjusted in an after-market imaging software application on your computer. Some of these proggies are free and quite easy to obtain and master.