Our test of the Pentax 645D is on the way, but in the mean time we would like to share the resolution chart images and the noise and dynamic range results.
Pentax's digital medium format 645D was announced back in March 2010. Priced at around £9,000 it features a 40 megapixel CCD sensor and 921k dot 3.0" LCD.
Initial results from the labs data have been compared against the Nikon D3x and Canon EOS 1Ds MKIII, whilst these SLR's have smaller sensors and are considerably cheaper, although not that cheap, all three cameras are perfectly suited to studio use.
The results show that all three cameras produce excellent results, but for both noise and dynamic range the Nikon D3x and Canon EOS 1Ds MK III just have the edge over the Pentax 645D.
However if you're wondering why you'd pay the extra for the Pentax 645D you only have to look at the results for resolution across the sensitivity range. The resolution results at ISO 200 for the Pentax 645D are a staggering 3,600 LW / PH, close to the maximum possible for our charts, compare this to the Nikon D3x's at a still impressive 2,800 LW / PH and the Canon EOS 1Ds MK III's at 2,600, and you can instantly see the benefits of the 40 mega pixel medium format sensor*.
* Pentax 645D sensor size 44mm x 33mm, True medium format 50.7mm x 39mm, full frame 36mm x 24mm
The Pentax 645D is available to buy now, with prices starting around £9000
Resolution charts
As part of our image quality testing for the Pentax 645D, we've shot our resolution chart with a Pentax smc D-FA 645 55mm f/2.8 lens mounted.
If you view our crops of the resolution chart's central section at 100% (or Actual Pixels) you will see that, for example, at ISO 100 the Pentax 645D is capable of resolving up to around 32 (line widths per picture height x100) in its highest quality JPEG files. However, this rises to 36 (line widths per picture height x100) at ISO 200 and above.
Examining images of the chart taken at each sensitivity setting reveals the following resolution scores in line widths per picture height x100:
JPEG resolution
ISO 100, score: 32 (see full image)
ISO 200, score: 36 (see full image)
ISO 400, score: 36 (see full image)
ISO 800, score: 36 (see full image)
ISO 1600, score: 36 (see full image)
Raw resolution
ISO 100, score: 32 (see full image)
ISO 200, score: 36 (see full image)
ISO 400, score: 36 (see full image)
ISO 800, score: 36 (see full image)
ISO 1600, score: 36 (see full image)
For a full explanation of what our resolution charts mean, and how to read them please click here to read the full article.
Noise and dynamic range
We shoot a specially designed chart in carefully controlled conditions and the resulting images are analysed using the DXO Analyzer software to generate the graphs below.
JPEG Signal to noise ratio
A high signal to noise ratio (SNR) indicates a cleaner and better quality image.
Our results for the JPEG images from the Pentax 645D indicate that despite the increase sensor size it generates a lower signal to noise ratio than the Nikon D3x and Canon EOS 1Ds MKIII.
JPEG Dynamic range
This chart indicates that the Pentax 645D's JPEGs compare well against the Canon EOS 1Ds MK III up to a sensitivity of ISO 400.
For more more details on how to interpret our test data, check out our full explanation of our noise and dynamic range tests.
RAW Signal to noise ratio
A high signal to noise ratio (SNR) indicates a cleaner and better quality image.
Raw images as with JPEGs from the Pentax 645D show a lower result for signal to noise ratio than both the Nikon D3x and Canon EOS 1Ds MKIII.
Raw Dynamic range
This chart indicates that the Pentax 645D's raw files score well at the lower end of the sensitivity range, however these results are dwafed by the Nikon D3x and Canon EOS 1Ds MK III.
For more more details on how to interpret our test data, check out our full explanation of our noise and dynamic range tests.
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