Phase One P45 Achromatic+

Product Name: Phase One P45 Achromatic+
Product Type: B&W digital capture system
Price: $49,950
Reviewed By: Paul Burrows
Magazine: Pro Photo: March 2011
Distributor: L&P Digital Photographic Supplies Pty Ltd
Who Sells What/Website: Phase One

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.

Seeing Red

The Phase One 645DF is based on the Mamiya 645 AFD series and shares the same AF and AE systems. Note the control arrangement around the handgrip which makes it very easy to use the AE lock or apply exposure compensation.

In infrared B&W photography, most of the visible spectrum is filtered out (except for some of the near-IR wavelengths) which means blues and greens record as black or very dark tones. This is particularly evident with blue skies, assisted by the high penetration of atmospheric haze. However, in bright sunny conditions foliage reflects a lot of IR light so leaves record as either a ghostly white or very light tones. Additionally, objects that have absorbed a lot of sunlight and are, consequently, hot, will also emit some IR radiation and be recorded as paler tones. Shooting at night after a very hot day can produce some very interesting effects.

The Achromatic+ sensor has only a thin protective glass on the ER (‘Extended Range’) version so the capture bandwidth extends into the UV and IR ranges.

The big challenge is working with an IR filter on the lens which almost completely blocks out the visible image, making framing and composition a challenge. An alternative is to use a dark ND filter which has no effect on near-IR transmission, but will allow for a little more to be seen in the viewfinder. However, as it’s also allowing more of the visible light spectrum to pass through, the IR effect will be reduced. Another option is to use a deep red filter, but obviously it’s possible to compose the image before fitting the filter. A challenge still remains, however, and that’s focusing accurately because the infrared wavelengths are refracted differently to the visible light wavelength (being longer, they refract or bend the least), requiring manual correction. In the old days of manual focus lenses, an infrared focusing index mark was provided, but with digital capture it’s possible to assess the sharpness on-the-spot and adjust the lens accordingly. Stopping down isn’t always a solution, as the diffraction effects can reduce sharpness, but it’s worth experimenting at f16 or f22.

The Phase One 645DF shown here with the 45mm f2.8 lens fitted. This compact wideangle (it’s equivalent to 29mm in 35mm format terms) proved to be extremely versatile in the field and was used exclusively for this test report.

It should be noted that apochromatic (Apo) lenses don’t have this problem as they’re corrected for near-IR wavelengths via their use of extra-low dispersion glass elements.

In The Field

To try out the Achromatic+ we headed west from a dull and overcast Sydney (the least conducive conditions for B&W IR photography), finally stopping just outside Bathurst where the plains were baking under a summer sun and impressive-looking storm clouds were developing, the fluffy white cumulus contrasting nicely with the dark blue sky.

The back was fitted to a Phase One 645DF camera body with Phase’s nicely compact 45mm f2.8 wide-angle lens. This focal length is equivalent to 29mm in the 35mm format and its optical construction includes low dispersion glass elements so we experienced few problems with focusing. In fact, determining the exposure was far more problematic because of the amount of IR radiation being reflected isn’t measured by the metering. Through trailand- error – obviously made very much easier by having a preview image to examine – we eventually settled on between –1.7 and –2.0 EV of compensation which produced good results with minimal correction required later in Capture One.

The 645DF is derived from the Mamiya 645 AFD so it has the same metering system which offers either average or spot measurements, but with an auto mode that automatically switches between the two when there’s a significant brightness difference between the centre of the frame and the surrounds. It’s nowhere near as sophisticated as what’s available on the latest small-format D-SLRs (or, indeed, the Pentax 645N), but there’s an AE lock and up to ±5.0 EV of compensation to help with fine-tuning. Likewise, the autofocusing employs only three zones, but the big optical viewfinder makes manual focusing a breeze and, of course, it’s the only option with B&W IR capture.

The Phase One camera handles comfortably and the Achromatic+ back employs a straightforward arrangement of four main control keys to access the key capture-related menus such as the ISO settings and white balance (although the latter shouldn’t really be an issue here). The 5.6cm LCD monitor screen is a bit on the small size these days (not to mention low-res at just 230,000 pixels), both issues that Phase One has addressed with its new IQ-series models, along with the rather rudimentary nature of a battery pack that’s clipped on to the outside of the back.

There’s 39 megapixels on tap and each one of them is solely devoted to recording a luminance level so the sensor delivers a real ‘raw’ resolution. We took the 60.5 megapixel P65+ along for the ride – then still flagship of the Phase One capture – converting these files to B&W in Capture One to make a direct comparison. While the P65+ still delivers more resolution, the Achromatic+ isn’t all that far behind so it’s probably safe to say it’s delivering sharper and better defined images than the colour P45+ by a long shot. The handling of fine detailing and textures is exceptional by 40 MP standards, but quite similar to what would be expected at 60 MP. However, the big difference is in the tonal gradation – which is much smoother – and a wider dynamic range with B&W capture. Add the ultra-wide bandwidth with both its technical and creative applications and the Achromatic+ isn’t as narrowly focused as might be expected. The fun factor is undeniable when shooting with the IR filter and there’s no doubt that more experimentation would lead to even more exciting and dramatic results. It’s a new way of seeing the world and one that isn’t at all gimmicky if used thoughtfully.

The Verdict

Infrared B&W effects vary according to the time of day and the weather conditions. The IR filter essentially blocks all of the visible spectrum so blue skies record as black. Foliage often records as white or very pale because certain leaves reflect a high level of UV light. Objects that have also been heated by the sun also emit near-UV radiation. This obviously makes determining exposures something of a challenge.

We’ve concentrated here mostly on the IR B&W aspects of using the Phase One Achromatic+, but it should also be pointed out that it delivers absolutely gorgeous results when used for ‘normal’ monochrome capture so its fine-art photography credentials are pretty good. That said, we still think many potential users are going to struggle with the price, even if Phase One is providing a ‘no compromises’ solution to digital B&W photography.

However, an Achromatic+ on, say, a Hasselblad 903SWC or perhaps an Alpa 12 TC fitted with a similarly ultra-wide lens would be as close to heaven as digital photography gets.



Type: Fully portable digital camera back for single-shot RGB capture plus a two exposure mode for double frame panoramas.
Supported Cameras: Hasselblad H System (excluding H3D/H4D series), Hasselblad V System, Hasselblad 903SWC, Mamiya 645AFD/II/III, Mamiya 645DF, Mamiya RZ67 Pro II/IID, Phase One 645AF and 645DF, Contax 645AF.View and wide-angle cameras via Hasselblad adapter plate.
Sensor Type/Size: CCD, 49.1 x 36.8mm
Number of Pixels: 39 million (7216 x 5412 pixels)
Focal Length Conversion Factor: 1.1x with 6 x 4.5cm format lenses
A/D Conversion: 16-bit monochrome
Storage Medium: CompactFlash Type II memory card
Data Compression: Lossless on IIQ RAW files, two levels (typical file sizes are 44 MB and 27 MB)
Sensitivity Range: ISO 50 – 800
Shooting Speed: Up to one frame every 1.5 seconds
Power Source: Rechargeable lithium-ion battery pack
Features: No Bayer RGB filters on sensor. XPose+ technology allows exposures of up to one hour. 640 MB high-speed RAM buffer. 5.6cm LCD monitor shows preview, histogram, exposure warnings and various status indicators. Dynamic range is 12 f-stops. FireWire interface for tethered operations, automatic rotation for horizontal and vertical framing, shutter speed range is one hour to 1/10,000 second. Available in two versions; CV (‘Classic Visible’) with a built-in IR/UV cut-off filter or ER (‘Extended Range’) without an IR/UV filter.
Price: $49,950 including GST.