The 24.6-megapixel Alpha A900 is Sony's first full-frame digital SLR and is aimed at professional photographers, especially studio-based pros looking for the ultimate in high resolution.
Raw and JPEG
JPEGs on their standard settings were about as soft as expected, and could generally do with a little boost in sharpness. Thankfully, Sony supplies its Raw-processing Image Data Converter software with the A900, which is fully featured with all main processing options.
Despite the odd over and underexposed image, the metering system kept within the margin of error we would expect, and studio tests showed the camera’s midtone to be neither too bright or dark. We used the Dynamic Range Optimiser on a number of occasions, and with seven separate options to choose from, what setting you use can make quite a difference to the final image. The process does give rise to noise and noisereduction artefacts in areas that have been ‘lifted’, though; for which reason the function seems a little redundant on a ‘pro’ model such as this one, when a more sensible option would be either to shoot Raw or at the very least to bracket exposures.
Anyone expecting the same sort of high-ISO performance the Nikon D700 displays will be disappointed, but with a sensor that’s twice as populated this probably should come as no surprise. Images shot at ISO 200 are detailed, though there’s a very slight granularity and some chroma noise in blue skies, while midtones at ISO 400 also reveal a little chroma noise. Despite a coarse texture and a fair helping of chroma noise, images do still remain fairly detailed and relatively sharp at higher sensitivities, though Raw files are noticeably sharper. The high-sensitivity noise-reduction settings do a good job of filtering out the coarsest chroma noise, but only the most conservative ‘Low’ option strikes a good balance between noise reduction and detail retention.
Colour and White Balance
The Auto White Balance system worked well, with just a few errors on its part. These seemed to bias towards producing slightly warm images. Mixed lighting is always a struggle for Auto White Balance systems, and one instance where we found inconsistencies was when shooting under a mixture of daylight and fluorescent light. In comparison with the closest preset (Daylight) the camera produced a very warm, magenta-toned cast. We also found this issue when shooting outside in sunny conditions, but for the most part it got it right.
Sharpness and Detail
With a little processing, Raw and JPEG files exhibit good detail and respond well to sharpening. Noise reduction is sometimes necessary before sharpening, as sharpening itself can make noise more pronounced.