The Ninja of Atomos is a field video recorder that records video at 10bit, uncompressed 4.2.2 colour space. What does this mean? It means that your colours will be deeper and if you do green screen production, your chroma-keying in will be much smoother -- there won't be any 'bleeding' of the screen to your subject.
More importantly, when you do 'heavy' post-production work like colour grading and online effects, your source video would not suffer loss of quality.
The Ninja records to Apple's virtually lossless ProRes format.