As with all cameras of this type, particular attention should be paid to results for Color Depth (24.2; average for 4 medium format cameras = 24.1) and Dynamic Range (12.9, average = 12.4).(see “Medium-format camera ranking with respect to the DxOMark Sensor Scale”).
Key sensor characteristics
The Phase One P45+ features a very high resolution medium-format CCD with 39.45 Mpix and a 16-bit Analog/Digital (A/D) converter. ISO latitude ranges from ISO 50 to ISO 800, but measurements show that the only two first ISO values (50 and 100) are real, a digital gain is applied during RAW conversion from ISO 200 to ISO 800.
Key performance factors
The Phase One P45+ shows excellent dynamic range and very good color sensitivity. With respect to its launch date, this result is quite good—only the newer high-end DSLRs show comparable results.
Per above, Color Depth is 24.2 bits in print mode. The result is lower in screen mode with a value of 20.8 bits, which means that noise can be observed even at ISO 50 on a larger print (with the same dpi) than the DxOMark reference print (12″ x 8″ print on a 300-dpi printer). Dynamic Range remains at a very acceptable level in screen mode.
Another key measurement is ISO Sensitivity. As described above, only the values for the lowest two ISO settings (50 and 100) are real; the other ISO values are achieved by applying a digital gain during RAW conversion. Curves and results for “non-real” ISO are extrapolated and shown with dotted lines on dxomark.com, and the Low-Light ISO value is computed from the extrapolated lines.
The Phase One P45+ RAW image quality performance results remain quite good today. Even though some high-end DSLRs are closing the gap in terms of pixel performance, the P45+ very high resolution capability keeps this camera among the few options available for very large size and high-quality professional print photography.
Disclaimer: This dxomark review evaluates only the selected camera’s RAW sensor performance metrics (i.e., Color Depth, Dynamic Range, and Low-Light ISO), and should not be construed as a review of the camera’s overall performance, as it does not address such other important criteria as image signal processing, mechanical robustness, ease of use, flexibility, optics, value for money, etc. While RAW sensor performance is critically important, it is not the only factor that should be taken into consideration when choosing a digital camera.