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Sony SLT Alpha A55 Dynamic Range (JPEG)

Our Dynamic Range measurement system involves shooting a calibrated Stouffer Step Wedge (13 stops total range) which is backlit using a daylight balanced lamp (98 CRI). A single shot of this produces a gray scale wedge from the camera's clipped white point down to black (example below). Each step of the scale is equivalent to 1/3 EV (a third of a stop), we select one step as 'middle gray' (defined as 50% luminance) and measure outwards to define the dynamic range. Hence there are 'two sides' to our results, the amount of shadow range (below middle gray) and the amount of highlight range (above middle gray).

To most people highlight range is the first thing they think about when talking about dynamic range, that is the amount of highlight detail above middle gray the camera can capture before it clips to white. Shadow range is more complicated; in our test the line on the graph stops as soon as the luminance value drops below our defined 'black point' (about 2% luminance) or the signal-to-noise ratio drops below a predefined value (where shadow detail would be swamped by noise), whichever comes first.

Note: this page features our new interactive dynamic range comparison widget. You can compare the dynamic range of images captured using the camera's various parameters, or you can select up to three other cameras to compare. The wedges below the graph are created by our measurement system from the values read from the step wedge, the red lines indicate approximate shadow and highlight range (the dotted line indicating middle gray).

The SLT A55 doesn't throw up any surprises as far as its dynamic range is concerned, and as you can see from the data in the graph above, in the 'Standard' Creative Style it has an impressive dynamic range which compares well to its DSLR competitors. Total dynamic range is almost 9EV, which is about as good as things get from the current crop of APS-C and full-frame DSLRs. It is interesting to note that the A55's dynamic range curve exactly overlays that of the Alpha NEX-5.

Some of the Creative Styles increase contrast a little - shooting in the Vivid and Landscape styles ensures very 'punchy' results, but with increased risk of highlight clipping as a result of the decreased dynamic range. The A55's 'BW' Creative Style also gives slightly higher contrast results than 'Standard'.

The effect of Sony's 'DRO+' settings differs depending on the scene, so this test, performed using our 18 step wedge, isn't necessarily an accurate indication of 'typical' performance with a real-world subject. It does clearly show, however, the way in which DRO+ is designed to work, extending by increments the amount of mid tones by lifting shadow areas to get the most detail out of these areas in a single exposure.

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Comments

Total comments: 6
sowow

I can only confirm that at least the first generation model is totally unreliable.
As others described often enough the camera would just turn off mid shooting, with only the first half of the shutter sound (shutter count 32k).

Sony insists on charging you for replacing the Shutter unit, which will likely die again within the next 15-50k.

Design flaws can happen, but Sony Customer Service is just terrible. Definitely not going to buy into their systems.

0 upvotes
Ranjansanath

It seems Sony A55 is very unreliable camera.

While I was taking photos, camera suddenly went black Fully dead. I verified battery is 100% charged.

I tried to contact the repair centre and no feed back. I am very much frustrated as my friend who took Cannon at the same time with me has had no issues with his and I have many other friends ho use Nikon never had issues with their cameras. I feel sorry for my decision to go for SONY DSLR.

1 upvote
BobFoster

I think that the fixed mirror means the cameras are relatively small -- 23 per cent smaller and 26 per cent lighter than the Sony Alpha DSLR-A550, to be precise. They're very light, but with a solid and comfortable rubberised grip.

2 upvotes
47872Mike

It does, or rather, did. Strangely, Sony decided, presumably for sound commercial reasons, to delete this body shape when they released the current model, the A58, which is bigger than the A55, 33, 35, and 37 which were all this shape. I like my cameras small (as well as light) so this shape definitely interests me more than the A58.

1 upvote
hrbaca

I love it. It is easy to use and I have never had any mechanical issues with it. I especially love the rapid shooting feature. My grandchildren never stay steady for a second. With this feature, I can go back and delete the frames I don't like. I also used it at professional sporting events at a great distance using the zoom lense with great success. I've also used the portrait function for stills. Great camera!

2 upvotes
MARMITE

I have not had a good time with this camera. Just over a year after buying it the camera stopped working and SONY charged me £117 for the repair. Now just 7 months later the camera has a different fault and will not focus or take photos. Sony want a further £117 for repairs!! I feel this is not what i expected from a camera at this price and SONY are not interested in the fact that possibly I have a poor quality camera. I would NEVER recommend a Sony camera to anyone

1 upvote
Total comments: 6