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ISO Accuracy

The actual sensitivity of each indicated ISO is measured using the same shots as are used to measure ISO noise levels, we simply compare the exposure for each shot to the metered light level (using a calibrated Sekonic L-358), middle gray matched. We estimate the accuracy of these results to be +/- 1/6 EV (the margin of error given in the ISO specifications). We found that measured ISO from the K-5 is roughly 1/3EV lower than indicated - so ISO 100 = ISO 80 (approx). This holds true throughout the entire ISO range, but a discrepancy this small has little practical impact upon everyday photography (remember that this test is performed in manual mode without reference to the camera's metering system).

Noise and Noise Reduction (JPEG)

This is our standard studio scene comparison shot taken from exactly the same tripod position. Lighting: daylight simulation, >98% CRI. Crops are 100%. Ambient temperature was approximately 22°C (~72°F).

Note: this page features our new interactive noise comparison widget. By default, we show you the default noise reduction settings of the camera tested, and three other models of the same class. You can select from all available NR options, and from other cameras. The 'tricolor' patches beneath the familiar gray/black/portrait images are taken from the same test chart, and show how noise impacts upon blue, green and red areas of a scene.

The Pentax K-5 offers six noise reduction settings - Off, Low, Medium, High, Auto and Custom. Auto is the default setting and calculates and applies an 'optimized' amount of noise reduction at each ISO step. The Low, Medium and High settings apply a constant level of noise reduction across the ISO range, and in custom mode the noise reduction can be defined by the user for each sensitivity setting.

The Pentax K-5's noise reduction does a remarkably good job and is pretty much on par with the best performing APS-C camera in low light that we've tested so far, the Nikon D7000 (not that much of a surprise as both cameras are built around the same sensor technology). At default settings the Pentax keeps a good balance between noise reduction and retention of fine detail up to very high ISO levels. At ISO 1600, which only a few years ago was the maximum ISO setting on many DSLRs, you can view the K-5's output at very large magnifications without noticing any noise or detail blurring, and even at 6400 noise doesn't get too intrusive in even letter-sized prints. Only at ISO 12800 and above the noise reduction turns really heavy-handed and visibly starts blurring fine (and even not so fine) detail, and at that headline maximum 51,200 setting almost all detail has gone.

Generally the differences in high ISO performance between the APS-C models of this latest generation of digital SLRs is fairly small. The K-5 uses a slightly more contrasty tone-curve than the Nikon D7000 but in terms of detail the difference between the two cameras is marginal. The Canon EOS 7D isn't far off but at ISO 3200 and above the Canon EOS 7D produces more chroma noise and also looses a little more detail. The performance gap to the Four Thirds Olympus E-5 is much wider though. The Olympus is visibly softer then the APS-C competition from ISO 1600 upwards and at 6400 offers a lower maximum sensitivity.

Please note: the noise graphs on this page show indicated ISO, not measured. We are working on an updated widget which will display measured ISO, but in the meantime, please bear in mind that the Nikon D7000's measured ISO is 1/3EV higher than indicated (so ISO 100 is actually ISO 125) and the Pentax K-5's measured ISO is 1/3EV lower than indicated (so ISO 100 is actually ISO 80). As already mentioned, this has little bearing on normal photography with either camera but it does make a difference to how you should interpret these graphs.

RAW noise (ACR 6.3 noise reduction set to zero)

Here we look at the RAW files processed through Adobe Camera Raw (in this case version 6.3). Images are brightness matched and processed with all noise reduction options set to zero. Adobe does a degree of noise reduction even when the user-controlled NR is turned off.

The amount of NR applied 'under the hood' is not high, but it does vary by camera (Adobe is attempting to normalize output across different sensors), so inevitably we are still looking at a balance of noise and noise reduction, rather than pure noise levels. However, the use of the most popular third-party RAW converter is intended to give a photographically relevant result, rather than simply comparing sensor performance in an abstract manner.

There are minor signs of noise even at the lowest sensitivity settings (remember these samples have noise reduction turned down to zero in ACR) but from ISO 400 upwards it becomes visible that the Pentax-K5 output is cleaner than some of the competition in this class. The gaps widens as you go up the ISO scale. A quick glance at the graphs shows us that the Pentax K-5 produces the best measured results in this test followed by the Nikon D7000 (which uses a very similar sensor); the Canon EOS 60D and Olympus E-5 are not quite on the same level. A closer look at the graphs, though, reveals a clear kink in the K-7's noise graphs at 1600, indicating that the camera applies some noise reduction even to the raw files.

Please note: the noise graphs on this page show indicated ISO, not measured. We are working on an updated widget which will display measured ISO, but in the meantime, please bear in mind that the Nikon D7000's measured ISO is 1/3EV higher than indicated (so ISO 100 is actually ISO 125) and the Pentax K-5's measured ISO is 1/3EV lower than indicated (so ISO 100 is actually ISO 80). As already mentioned, this has little bearing on normal photography with either camera but it does make a difference to how you should interpret these graphs.

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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.

9 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