This is the second post in the hardware vs software series. The first one is on graduated neutral density filters.
Nearly all digital cameras have a Black&White mode which renders images as shades of grey, similarly to black-and-white films. Since digital camera sensors – with one exception – filter light by primary colors, this setting does not apply to RAW files. It almost always renders in JPEG image format. In the majority of cases, this means there will be at most 256 shades of grey. The few cameras that also support TIFF can output more shades, up to 4096 currently.
Pretty much all image processing software, including Adobe’s Lightroom and Photoshop CS6, can transform a color image into a black and white one. The obvious question is: Is there a difference between converting to B&W in-camera versus in-software?
Yes, there is a huge difference: You cannot change your mind if you set your camera to B&W.
Another difference is that there are multiple ways of converting to B&W. The usual way is to use luminance but some people favor certain colors during the conversion. In the film days, it was possible to use a colored filter with B&W film to affect the resulting look. Some cameras let you control this in-camera but you have a limited number of options, between 0 and 12 is typical.
Then again, with complete confidence that this is what you want, there is not need waste your time on a computer.