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ISO Accuracy

The actual sensitivity of each indicated ISO is measured using the same shots as are used to measure ISO noise levels, we simply compare the exposure for each shot to the metered light level (using a calibrated Sekonic L-358), middle gray matched. We estimate the accuracy of these results to be +/- 1/6 EV (the margin of error given in the ISO specifications). Measured ISO from the SLT A55 is within +/- 1/6 EV of indicated ISO across its entire ISO range.

Noise and Noise Reduction (JPEG)

This is our standard studio scene comparison shot taken from exactly the same tripod position. Lighting: daylight simulation, >98% CRI. Crops are 100%. Ambient temperature was approximately 22°C (~72°F).

Note: this page features our new interactive noise comparison widget. By default, we show you the default noise reduction settings of the camera tested, and three other models of the same class. You can select from all available NR options, and from other cameras. The 'tricolor' patches beneath the familiar gray/black/portrait images are taken from the same test chart, and show how noise impacts upon blue, green and red areas of a scene.

As you can see from these images, it is only at ISO 800 that visible noise starts to creep into the A55's JPEG output, but not to the extent that it is problematic in normal-sized prints. Even at ISO 3200 the A55 is capable of producing very good image quality which is at least on a par with the best of the other cameras in its class. By ISO 12,800 image quality has dropped significantly but high-contrast detail remains impressively well-defined, making this setting genuinely useful, rather than for 'emergency use only'.

We've also included an example of the A55's 'Multi-shot NR' ISO 25,600 mode, and as you can see, image quality is slightly higher using this function than it is at ISO 12,800. Of its competitors, the A55 offers the best performance in our measured noise tests, and it is interesting to see how much higher measured noise levels are from the Panasonic Lumix DMC-G2, which uses a smaller Four Thirds sensor.

With noise reduction set to 'auto' (default) the Alpha 55 matches the NEX-5 noise performance until ISO 3200, beyond which it manages to produce slightly less chroma and gray noise, ultimately managing almost a 1EV improvement over the NEX's 14MP CMOS sensor. When both cameras are set to NR 'weak' the gap is narrower. The difference between the visual output of these two settings is subtle, to say the least, until the ISO is increased to 3200 and higher, at which point 'auto' gives smoother but slightly less detailed results.

RAW noise (ACR 6.2 noise reduction set to zero)

Here we look at the RAW files processed through Adobe Camera Raw (in this case version 6.2). Images are brightness matched and processed with all noise reduction options set to zero. Adobe does a degree of noise reduction even when the user-controlled NR is turned off.

The amount of NR applied 'under the hood' is not high, but it does vary by camera (Adobe is attempting to normalise output across different sensors), so we are still looking at a balance of noise and noise reduction, rather than pure noise levels. However, the use of the most popular third-party RAW converter is intended to give a photographically relevant result, rather than simply comparing sensor performance in an abstract manner.

All the cameras show signs of noise even at the lowest sensitivity settings (remember these samples have noise reduction turned off) but up to ISO 400 the difference between them is pretty marginal. At higher ISOs the SLT-A55 is again pretty much on the same level as its APS-C competitors but visibly better than the Micro Four Thirds Panasonic G2.

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Total comments: 7

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.


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

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.


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

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!


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

hey, sorry for your bad luck. Sony manufactures good, but sometimes quite unreliable cameras, I agree.

Total comments: 7