Ricoh-Pentax announces the first affordable monochrome-only digital camera

Ricoh-Pentax has announced the rumoured Pentax K-3 III Monochrome, a new version of the existing Pentax K-3 III DSLR, this time with no colour filter array on its 26-megapixel APS-C sensor.

Pentax K-3 III Monochrome – top

Besides the central feature of the camera – its monochrome sensor – there are a lot of small tweaks and changes making the camera somewhat unique in today’s market, even for Pentax. All the graphics on the camera body, which would usually be coloured white, green or red, are now in three different shades of grey. Top-plate LCD screen backlight was changed from green to white, and even the menus are available as the monochromatic version. The camera is even capable of recording 4K video – monochromatic 4K video! How cool is that!?

Why monochrome?

A monochrome-only camera can be seen as a downgrade, an unnecessary limitation – colour photos can always be converted to monochrome, but the other way around simply doesn’t work; once the colour information is discarded, there is no way to reproduce the colours of a photo in any meaningful way.

So why would anyone want a camera limited like that? Because monochrome-only sensors have some unique properties, and, finally, using a monochrome-only camera presents a choice made by the photographer, as an artist.

Digital sensors, either CMOS or CCD, are, except in some special cases, inherently monochromatic devices, they can measure the amount of light falling on photo-sensitive elements, sensels (pixels are elements of an image, sensels are actual, physical elements producing pixels), and nothing more. To get the colour information, virtually all modern sensors used in non-specialized, consumer cameras are using colour filter arrays. Not to wade too deep into digital colour theory and practice, colour filter arrays are a mosaiced layer over the sensels, allowing only red, green or blue colour to reach the sensel behind them. That means sensels don’t have full-colour information, but only about their specific colour, and to achieve a full-colour photo, demosaicing algorithm needs to be applied to interpolate full-colour info for each pixel. Colour filter arrays in modern cameras are using Bayer colour patterns, the process of interpolating colour information from single colour pixels is called de-Bayering.

De-Bayering is a lossy process, some info needs to be interpolated, assumed depending on colour info from the surrounding pixels. That also means colour photos can be less sharp than theoretically possible, because of the interpolation process. Also, there is a colour noise introduced by the process, known as chroma noise.

Monochrome sensor, obviously, doesn’t need a colour filter array, there is no interpolation step involved, and the resulting image is created from the full data available, with full theoretical sharpness (no interpolation, remember), and no chroma noise. Luminance noise is still present, but in practice, luminance noise is perceived as organic, it is significantly less obtrusive than chroma noise, leading to more pleasant photos, even when noisy. Increased sensitivity is also a benefit since there are no interpolation losses.

Basically, from a technical standpoint, a monochromatic sensor trades off colour information for increased sharpness, less and more pleasant noise, and increased sensitivity.

Why the effort?

While there are other monochrome-only digital cameras on the market, up until Pentax K-3 III Monochrome, those options were very high-end – Leica M-series rangefinders (M9, M10 and M11 Monochrom), Leica Q2 Monochrom fixed-lens camera, and PhaseOne Achromatic digital medium format backs. Industrial and surveillance sensors are also often monochromatic, but just like Leicas and PhaseOne backs, the target market for those cameras is limited, and more in the domain of theoretical discussion, than real-world photographic practice.

Although far from cheap, with an MSRP of 2200 US$, its price is within reach of amateur and enthusiast photographers, even with a potential lens included in the price. With more sales, the second-hand market will also be an option.

The point of this effort is in having an artistic option. It’s been decades since the last time Pentax was an option for a working professional photographer. Obviously, by not even trying to compete with mirrorless cameras from all other manufacturers, Pentax is now in a unique position – Pentax is the last, and the only, manufacturer actively building and improving DSLR cameras. Sticking to DSLR cameras, its user base is very limited, and expanding it, and selling more cameras and lenses means introducing new and different ideas aggressively. Monochrome DSLR is a perfect idea for that – it might make old users more willing to buy a new camera body since it is not just an incremental upgrade, and because of the relatively acceptable price, new users would not be totally out of the question.

Final word

Taking into account all the pros and cons, this camera makes all the sense for Pentax to make. It might pull new buyers, it might soften existing Pentax owners to upgrade, significantly easier than just another iteration of any existing Pentax camera.

It is also a relatively low-effort and high-impact move, reusing the well-known platform once more. If there will be more people actively asking the company for a monochrome edition of the higher-end, full-frame Pentax K-1 camera, or even a dedicated monochrome edition of the Ricoh GR III compact camera, it could be reasonable to expect Pentax to yield to requests – just like they did for this camera, it was specifically asked for from the community.

Finally, a welcome breath of fresh air from Pentax.


Most significant specifications. For a full specification list, see here on DPReview.

Pentax K-3 III Monochrome
IntroducedApril 2023
Sensor sizeAPS-C, 1.5×
Effective pixels26 megapixels
Weight820 g
Dimensions135 × 104 × 74 mm (W × D × H)