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Pentax K-5 Dynamic Range (JPEG)

Our Dynamic Range measurement system involves shooting a calibrated Stouffer Step Wedge (13 stops total range) which is backlit using a daylight balanced lamp (98 CRI). A single shot of this produces a gray scale wedge from the camera's clipped white point down to black (example below). Each step of the scale is equivalent to 1/3 EV (a third of a stop), we select one step as 'middle gray' (defined as 50% luminance) and measure outwards to define the dynamic range. Hence there are 'two sides' to our results, the amount of shadow range (below middle gray) and the amount of highlight range (above middle gray).

To most people highlight range is the first thing they think about when talking about dynamic range, that is the amount of highlight detail above middle gray the camera can capture before it clips to white. Shadow range is more complicated; in our test the line on the graph stops as soon as the luminance value drops below our defined 'black point' (about 2% luminance) or the signal-to-noise ratio drops below a predefined value (where shadow detail would be swamped by noise), whichever comes first.

Note: this page features our new interactive dynamic range comparison widget. The wedges below the graph are created by our measurement system from the values read from the step wedge, the red lines indicate approximate shadow and highlight range (the dotted line indicating middle gray).

Custom image modes

At default settings (Bright) the K-5's tone curve is more or less identical to its predecessor, the K-7. It measures a total dynamic range of 8.5 EV, just 2.9 EV of which are in the highlights with a rather abrupt clip to white. The Bright, Natural, Portrait, Landscape, Vibrant, and BW settings use essentially the same curve and therefore produce the same amount of dynamic range. The Muted setting uses a more linear, less contrasty curve. Bleach Bypass and Reversal Film on the other hand create images with more contrast. However, all the settings clip highlights at the same point.

The tone curve remains essentially unchanged across the ISO range (all ISOs clip at the same point) but at higher settings shadow dynamic range is limited by shadow noise.

Expanded Dynamic Range Function

The K-5 features a highlight expansion function which applies to both JPEG and RAW; shadow expansion can also be applied to the camera's JPEG output. With Highlight correction activated ISO 160 becomes the minimum sensitivity setting, and the tone curve is flatter in the highlights giving an extra stop or so of highlight range. If you compare the K-5's dynamic range curve with hghlight correction turned on against the Nikon D7000's default output, you can see that they match almost exactly. Since the two cameras share closely-related sensors, this strongly suggests that the Nikon is essentially performing an equivalent to highlight correction by default. The noise floor of both cameras is low enough to do so without any serious penalty in noise levels, and for this reason we'd recommending keeping highlight protection activated on the K-5.

With our dynamic range test setup we could not trigger the K5's shadow correction functionality and therefore we can unfortunately not provide any measurements for this feature. In normal use, shadow correction has a very subtle effect, but it does help lighten shadows slightly in contrasty scenes.

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Comments

Total comments: 4
ANTMANT
By ANTMANT (4 months ago)

Brilliant camera with stunning noise control, this is my own test of every ISO level: https://www.flickr.com/photos/antmant/13507776774/

0 upvotes
oldnoob
By oldnoob (9 months ago)

When compared in RAW with the k-5II and the k-5IIs, the k-5 is clearly back-focusing. Compare the three cameras and center on the queen of hearts and look at the wall behind it. And also compare the left top checker test pattern in the test scene.

Comment edited 25 seconds after posting
0 upvotes
eclat
By eclat (10 months ago)

What I find so disingenuous (and irritating) about these otherwise wonderful reviews is dpr's clear bias toward Canon and Nikon. The exact same specs can be found on a Pentax, but what we'll get is a measured, sometimes even tepid nod, while with the Canon/Nikon, there will be an enthusiastic thumbs up for the same feature. The Pentax line (as the most obvious example) is held to a different standard, it seems.

Take the Pentax K5 review, for example, which is called a "serious amateur's" camera and yet is compared to its "direct competition," the Canon 7D and Nikon D300s, cameras that are for "keen enthusiasts, professionals and aspiring-professionals..." and "semi-pros" respectively. Apparently Pentax "serious amateurs" are equal to Canon and Nikon "pros and semi-pros." We always knew that, of course, but still... try to be a little more objective in your reviews and a little less biased, one way or the other.

10 upvotes
Reeuwijk
By Reeuwijk (11 months ago)

Dear sir,

How is it possible that the Pentax K 5 has a higher resolution than the Pentax K5 II/IIS?

Brant van der Goot

2 upvotes
Total comments: 4