Sony A55 High ISO NR
Sony A55V High ISO Noise Reduction
The Sony SLT-A55V offers only two high ISO noise reduction settings: Auto and Weak, with Auto being the default. The A55V user manual does not say at what ISO noise reduction kicks in, so we've included crops starting from the base ISO of 100. We've also included crops from the new Multi-frame Noise Reduction mode, which shoots a burst of six images with a single press of the shutter button and combines them in-camera to average out a lot of noise.
See for yourself how the noise reduction works under daylight-balanced lighting. Click on any of the crops below to see the corresponding full-sized image.
The above crops show the effects of the Sony A55V's two high ISO noise reduction settings, plus Multi-frame Noise Reduction under our studio HMI lighting we use to simulate daylight. As you can see, the "Weak" setting does result in more chroma noise than the Auto, but it also smudges the detail in the red fabric at higher ISOs. (You can really see a difference at ISO 1,600 and above.) Multi-frame Noise Reduction takes a burst of 6 shots and combines them to average out noise. This new mode is similar to Hand-held Twilight, but gives you control over ISO and exposure mode (PASM). It produces some very clean, detailed images and also extends the available ISO settings to 25,600, but requires the use of a tripod at slower shutter speeds, so similar results can be obtained by simply shooting at a lower ISO with longer exposures if you're already using a tripod.
Let's see how the Sony A55V compares to its less expensive sibling, the A33 as well as the NEX-5 and the Canon T2i.
The 16.2-megapixel Sony A55V performs quite well in this group. It performs similar to the 14.2-megapixel Sony A33 and NEX-5 despite having smaller photosites, though it does seem to be applying slightly stronger noise reduction. It holds on to detail a bit better in the red leaf fabric than the 18-megapixel Canon T2i, but the T2i renders edges better at higher ISOs. We'll have to wait until dcraw supports the new Sonys to see how their new sensors perform without any noise processing.
Note that the last set of crops here were taken with Sony's new Multi-frame Noise Reduction feature, so noise levels are vastly lower than they would be if the cameras supported ISO 25,600 in the standard single-capture mode.