Phase One has designed the Achromatic+ as a pure B&W-only capture device and the digital equivalent of the scientific B&W films. Report by Paul Burrows.

Phase One’s Achromatic+ back is based on the colour P45+, but is dedicated to pure B&W capture.

Back in the early days of digital capture there were a couple of B&W-only D-SLRs – Kodak’s DCS 420m and 460m from the mid-1990s spring immediately to mind (there was also an IR version of the 420) – but then the idea of a dedicated digital camera for monochrome work seemed to fade away. True, it became easier to satisfactorily convert RGB colour images to B&W, particularly from RAW files, but there are many compromises associated with using a colour capture system from the sensor design and on ‘downstream’. And, of course, we always had B&W films with the enhanced resolution achievable when colour dyes weren’t involved (with the exception of Kodachrome) and the availability of extended spectral sensitivity for specialised applications.

Fitted with the Phase One TG1 filter, the Achromatic+ back captures just the visible spectrum, but the resulting B&W images exhibit an excellent dynamic range with exceptionally smooth tonal gradations.

The reality is that demand for a dedicated B&W digital capture system – particularly for scientific work and fine-art photography – has never really gone away, but it’s been so small that none of the camera companies have responded. And very few of these companies would be prepared to take the if-we-built-it-they-will-come approach, even if this is undoubtedly the case. Now Phase One has taken the plunge, adding more kudos to the brand that’s rapidly becoming the most active and progressive in the digital medium format business. The impetus for the P45 Achromatic+ came from one of Phase One’s US resellers with a lot of scientific photographers among its customer base. They were still shooting film, but specialised B&W emulsions are going out of production so they were desperate for a digital solution. However, even the highest resolution colour sensors weren’t satisfactory so Phase One agreed to make the Achromatic+ (the name translates as ‘without colour’) based on the P45+.

The Price Of Exclusivity

A camcorder-style battery pack clips to the side of the Achromatic+ capture back.

What’s immediately noticeable is that the Achromatic+ is more than twice the price of the colour P45+ even when you might think it might be a less complex device. The issue here is the sensor which has to be hand-picked and much more rigorously tested because pixel drop-outs are much more problematic when there isn’t a Bayer RGB colour filter to ‘cover’ for these defects. It costs a lot to divert a small number of sensors from the standard production line and then probably reject a higher proportion of them than would normally be the case. Thus the sensor in the Achromatic+ is a very rare – and expensive – beast indeed, but it’s also a remarkable performer.

Phase One’s P-series capture backs employ a very straightforward control arrangement based on four function keys positioned on either side of the monitor screen.

With the R,Gx2,B matrix filter layer gone along with the subsequent colour interpolation processing, the resolution is significantly boosted which is why all those pixels have to work. Also eliminated is the so-called low pass filter (LPF) which reduces the sensitivity to the infrared wavelengths (and UV light) in order to ensure more accurate colour reproduction. Leica got itself into a bit of strife here when it dropped the LPF from the M8 with the objective of improving image quality, but instead everybody complained about the colour reproduction so a costly lens filter fix was required.

Phase One is offering the Achromatic+ in two versions – one with a ‘plain’ sensor which only has a protective glass in front of it and nothing else and one with an IR/UV cut filter. The first version is designated ER (for ‘Extended Range’) and obviously it records not only the visible light spectrum, but the near UV and IR wavelengths as well. This provides the wide bandwidth ‘base’ required for applying selective filtration so, for example, only the infrared wavelengths are recorded which, in B&W, can look very dramatic indeed. For this reason, the ER Achromatic+ is really the one to have as Phase One also supplies an IR/UV-cut lens filter (designated TG1) so the visible spectrum can be recorded normally. The creative possibilities of infrared B&W photography are the icing on the cake of the ER version... and might just help make that $50k+ price tag a bit easier to justify.