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ISO Sensitivity / Noise levels (contd.)

In-camera High ISO noise reduction
Updated Feb 2009 (Firmware V4)

The DSLR-A700 provides four different levels of noise reduction on images at ISO 1600 or higher; Off (with latest firmware), Low, Normal and High. As you can see from the graph below using the High setting doesn't reduce noise by very much more and using the Low setting doesn't reduce noise reduction very much. There is some noise reduction even at the 'off' setting in JPEGs (though it does appear that at this setting - and only at this setting - the noise reduction on raw files is turned off completely)

Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity on the vertical axis (note that the standard deviation scale here has been extended 2x compared to the graphs on the previous page).

Noise reduction crop comparisons (ISO 1600 - 6400)

Off
ISO 1600

Low
ISO 1600
Normal
ISO 1600
High
ISO 1600

Off
ISO 3200
Low
ISO 3200
Normal
ISO 3200
High
ISO 3200

Off
ISO 6400
Low
ISO 6400
Normal
ISO 6400
High
ISO 6400

Noise reduction on 'RAW' image files
Updated Feb 2009 (Firmware V4)

When Sony first shipped the Alpha 700 it was heavily criticised for applying noise reduction to raw files (or more specifically for not allowing users to turn this behaviour off, leaving the photographer with no option other than to simply accept Sony's decisions on noise reduction. To its credit Sony heard the complaints and fairly quickly responded with a new firmware (click here for our news story). This adds the option to turn off the high ISO noise reduction, though you still can't have the NR turned on for JPEGs without the accompanying raw file also getting it (unlike most cameras, where NR is preserved for JPEGs only).

The crops below show the effect of this noise reduction on raw files using the original (V2 in this case) and the latest (V4) firmware. As you can see we're not talking about a subtle amount of NR here:

DSLR-A700 RAW
High ISO NR off (v4)
ISO 1600
DSLR-A700 RAW
High ISO NR on (v2)
ISO 1600
DSLR-A700 RAW
High ISO NR off (v4)
ISO 3200
DSLR-A700 RAW
High ISO NR on (v2)
ISO 3200

Below we have a comparison of in-camera JPEG (Noise reduction at lowest setting) to RAW converted using Adobe Camera RAW with its Noise Reduction options set to zero (effectively 'no noise reduction') for the Alpha 700 and Nikon D300. With the new firmware we get a far clearer picture of the amount of noise in the images (and that although the Sony sensor is fractionally noisier than the D300, there's lots of detail to work with than the JPEGs would suggest).

DSLR-A700 JPEG
ISO 1600
DSLR-A700 RAW NO NR
ISO 1600
D300 JPEG
ISO 1600
D300 RAW NO NR
ISO 1600
DSLR-A700 JPEG
ISO 3200
DSLR-A700 RAW NO NR
ISO 3200
D300 JPEG
ISO 3200
D300 RAW NO NR
ISO 3200
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