Sony SLT-A55V Review

 
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Sony SLT-A55 High ISO RAW Image Quality

We look at RAW files converted with dcraw, an excellent freeware raw converter. dcraw usually offers timely support for the latest cameras, but more importantly, it does not apply any noise-reduction, sharpening or other corrections such as geometric distortion correction to the output files as some other converters do. There will always be differences between RAW converters, in terms of the sort of demosaicing algorithms they use (the processes by which they convert the separate Red, Green, and Blue data sets to an array of full-color RGB pixels), but dcraw seems to use a fairly generic algorithm that delivers good sharpness with relatively few artifacts, and can be counted on to not apply any noise reduction if you don't want it to.

Below are crops from Sony A55's 12-bit RAW files compared to RAW files from other similarly-priced APS-C SLRs, converted with dcraw.

High ISO RAW Comparison with
Canon T3i, Nikon D5100 and Sony A580
RAW files converted with dcraw, no NR, no sharpening
Daylight-balanced illumination
Sony A55
Canon T3i
Nikon D5100
Sony A580
I
S
O

8
0
0
Sony A55
Canon T3i
Nikon D5100
Sony A580
I
S
O

1
6
0
0
Sony A55
Canon T3i
Nikon D5100
Sony A580
I
S
O

3
2
0
0
Sony A55
Canon T3i
Nikon D5100
Sony A580
I
S
O

6
4
0
0
Sony A55
Canon T3i
Nikon D5100
Sony A580
I
S
O

1
2
8
0
0
Pentax K-7
Canon T3i
Nikon D5100
Pentax K-7
I
S
O

2
5
6
0
0
N/A
ISO 25,600
Not Supported
N/A
ISO 25,600
Not Supported
N/A
ISO 25,600
Not Supported
N/A
ISO 25,600
Not Supported
N/A
ISO 25,600
Not Supported
N/A
ISO 25,600
Not Supported
N/A
ISO 25,600
Not Supported
N/A
ISO 25,600
Not Supported
N/A
ISO 25,600
Not Supported

Here, we can see that the Sony A55's RAW files contain very similar noise and detail compared to the Sony A580, which is no surprise, since they share the same sensor, however the A580 does a touch better with reds. The Nikon D5100 has a slight edge over the other three in terms of noise performance, while the Canon T3i trails slightly in this group. Overall, an impressive performance from the Sony A55.

 

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Note: For details, test results, and analysis of the many tests done with this camera, please click on the tabs at the beginning of the review or below.

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