Ten frames per second with continuously active AF is no mean feat, especially in a camera costing £700. Whether it is worth the loss of the optical viewfinder is another matter
Noise, resolution and sensitivity
At 16.2 million pixels, the Alpha 55 makes use of Sony’s highest-ever resolution APS-C-sized sensor, combined with sensitivity of up to ISO 12,800 (expandable to 25,600 in multi-frame NR mode).
Because of issues concerning compatibility with the Sigma 105mm f/2.8 macro lens and the Alpha 55, I shot our resolution charts using the 18-55mm f/3.5-5.6 SAM kit lens set to around 50mm at f/13. Results were as I expected for a 16.2-million-pixel camera, with resolved detail at 26 and a gradual drop off to 22 at ISO 1600, and then 20 beyond that. While resolution is respectable, detail in my images is generally a little soft.
Noise levels at ISO 100 and ISO 200 are particularly well controlled. Noise starts to become apparent at ISO 800, but the results are still respectable. Even up to ISO 3200 the Alpha 55 produced reasonable results.
Chroma and luminance noise are much more noticeable at ISO 12,800, and smudging results in images that are not as sharp. However, when compared to the competition there are no specific issues worth mentioning, and I am particularly pleased with image quality in my images at ISO 100-200.
These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured using a Sony’s 18-55mm f/3.5-5.6 kit lens. We show the section of the resolution chart where the camera starts to fail to reproduce the lines separately. The higher the number visible in these images, the better the camera’s detail resolution is at the specified sensitivity setting.
Image: There is a good level of detail throughout the ISO range, and the Alpha 55 performs particularly well at ISO 100