The Leica M Monochrom introduced in 2012 was the solution provided by Leica for anyone who wanted to shoot true black and white photos with a digital camera. Being a Digital Rangefinder, the optical viewfinder doesn't show the image through the lens, instead a small central window is used to focus the camera.
The Leica M Monochrom features a full frame black and white 18 megapixel CCD sensor, and costs around £5500-£6000 body only. Alternatively a colour Leica M-E (with 18 megapixel colour sensor) costs £4000 body only, and images can be converted to black and white, or the Leica M (Typ 240) is around £5100 body only, and features a 24 megapixel colour sensor, with live view and full HD video recording.
Being the only true black and white digital camera since the Kodak DCS Pro SLR/n m monochrome (2004), the only other options available today are the Phase One IQ260 Achromatic a 60 megapixel medium format digital back, and the Phase One Achromatic+, a 39 megapixel version, which is slightly more expensive than the Leica M Monochrom at $45,000.