PhaseOne Achromatic+ vs. P45 conversion

During my test shooting with the PhaseOne Achromatic+ digital back, I could get a direct comparison between the black and white images shot with the Achromatic+ back and those created from color images, shot with the PhaseOne P45 back and standard conversion in Photoshop. All three images are downsized to a width of 1200 pixel. The camera, a PhaseOne 645DF and the 80mm Schneider-Kreuznach lens were identical during the shooting. The same is true for the light setup in the studio.

The first image shows the food still life setup, used for the test and the color reference file:

PhaseOne P45 reference image

Using Capture One for the RAW conversion to a 16-bit .tiff file and the Chanel Mixer in Photoshop to obtain the black and white image gives us the following image:

PhaseOne P45 back, black & white image, conversion in Photoshop

The same scene, shot with the Achromatic+ pure black and white back without any further manipulation in Photoshop or similar looks like this:

PhaseOne Achromatic+ image file

The saturation and look of the two black and white images differ of course. The aim was to bring out the maximum of fine structured details as much as possible. The overall look of the black and white image obtained through conversion from the P45 color image is a bit more saturated with slightly higher contrast – similar to the use of a "B+W 090 red filter".

Which digital back is delivering the "better" black and white image ?

As most of us would have guessed – The answer would be "It depends". The amount of detail is enormous in both images, looking at the cropped sections (100%, native image resolution).

PhaseOne P45 image detail, black & white conversion Photoshop, 100% crop

PhaseOne Achromatic+ image detail, 100% crop

Small differences in the smoothness of the transition from "dark" to "bright" is visible, especially in the image sections were spots of a bright glow, caused from reflected light, are visible on the dark grains of corn. Both images were taken at ISO100 with the same lens and f=16. The Achromatic+ image shows a little bit less “noise” in the low key sections.

Looking at single grains, preferably those with a "rough" surface, one can see a slightly smoother transition from dark to bright tones. As already seen in the architecture shots, the advantage of the Achromatic+ becomes evident in cases where smallest details and finest structures have to be reproduced in high resolution.

The next image makes this clear in an impressive way:

PhaseOne Achromatic+ image, 80mm lens

The image was shot at f=16 with the focus on the Cathedral in the middle of the image.

The following image shows a 100% crop of the above image without any sharpening or other image enhancement. I would like to draw your attention to the wires of the maintenance installation on the left hand side of the tower.

PhaseOne Achromatic+, image detail, 100% crop

When it comes to pure image resolution and separation of smallest structural details, the Achromatic+ is for sure the “ultimate choice” for the black and white photographer.

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