Sony Alpha 7S Review
Sony Alpha 7R Review - Image Quality
With a 12.2-million-pixel sensor you wouldn't expect to resolve a spectacular amount of detail, and indeed it doesn't.
At ISO 100 the A7S reaches around 24 lines per mm in our resolution chart lab testing, which is exactly what you would expect for a camera of its resolution.
With such good control of noise the resolution doesn't drop as the sensitivity increases.
At ISO 50, we found that the A7S has a dynamic range of 13.26EV, which makes it around 0.5EV better than the 12.75EV that Nikon D4S recorded a few months ago.
At ISO 200 and 400, the dynamic range of both cameras is virtually identical. What this means in practice is that the 12.2-million-pixel, full-frame sensor is able to recover a great amount of detail in highlights, particularly in shadow areas.
Combined with the high sensitivity range it really is able to see in the dark.
Obviously the extreme sensitivities are noisy, with plenty of luminance and colour noise on show. However it is the more ‘reasonable' sensitivities of ISO 6,400, 12,800 and 25,600 where the A7S really shows what it can do. These sensitivities are as usable as ISO 1,600, 3,200 and 6,400 in other full-frame cameras.