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ISO Sensitivity / Noise levels (contd.)

In-camera High ISO noise reduction

Although the default option on the K2000 is to apply very little noise reduction there is an option to apply more for smoother, but less detailed, JPEGs. The Pentax offers four levels of high-ISO Noise Reduction named, somewhat interestingly as: off, weakest, weak and strong - which is a good level of control for a camera at this price. What's a little odd though, is that the default setting is 'off.' While this is ideal for users who want to apply their own noise reduction in post-processing, it's an odd choice when all the other settings on the camera default to over-saturated, no post-processing-needed compact-camera-like punchiness.

The naming of the noise reduction settings could be made clearer: the different settings do more than just change the magnitude of the noise reduction. As the graphs below show (if you move your mouse over the different tabs), the noise reduction settings have no effect until IS0 800. The Weakest setting applies no additional luminance noise reduction but reduces chroma noise a little. The Weak setting applies much more heavy noise reduction to both luminance and chroma, while the Strong setting just adds a tiny bit more reduction to both.

From both the graphs and the crops below, it appears that 'Weakest' probably strikes the best balance between retaining detail and reducing noise, up to ISO 1600. (At ISO 3200 it's pretty much academic)

Black Gray Chroma

Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity on the vertical axis.

In-camera High ISO noise reduction Off / On (ISO 200 - 1600)

Pentax K2000
ISO 800
ISO NR Off
Pentax K2000
ISO 800
NR Weakest
Pentax K2000
ISO 800
NR Weak
Pentax K2000
ISO 800
NR Strong

Pentax K2000
ISO 1600
ISO NR Off
Pentax K2000
ISO 1600
NR Weakest
Pentax K2000
ISO 1600
NR Weak
Pentax K2000
ISO 1600
NR Strong

Pentax K2000
ISO 3200
ISO NR Off
Pentax K2000
ISO 3200
NR Weakest
Pentax K2000
ISO 3200
NR Weak
Pentax K2000
ISO 3200
NR Strong

RAW noise compare

Finally we look a the K2000's raw output next to its peers. Removing any in-camera noise reduction and processing the images using Adobe Camera Raw (V5.2 in this case, all NR set to 0) gives us the nearest thing to a 'level playing field' for assessing the relative noise levels of the three cameras' sensors.

The Pentax sensor seems to be more prone to chroma noise than any of its peers but its luminance noise is consistently a little lower. This suggests that, even with High ISO noise reduction at its 'off' setting, the camera is applying quite high levels of chroma noise reduction in its JPEGS.

Pentax K2000
ISO 800
Canon EOS 1000D
ISO 800
Sony DSLR A200
ISO 800
Olympus E420
ISO 800

Pentax K2000
ISO 1600
Canon EOS 1000D
ISO 1600
Sony DSLR A200
ISO 1600
Olympus E420
ISO 1600

Pentax K2000
ISO 3200

Canon EOS 1000D
N/A

Sony DSLR A200
ISO 3200
Olympus E420
N/A

 

 

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