Digital Cameras Guide
Image Performance II
Image Performance - Image Noise
On the previous page, we said that the high amount of detail and the wide dynamic range in the D800's images come with a price, and that price is higher image noise. With more detail, we also see more image noise in the D800's images. But - and here is where it gets complicated - we are also looking at much larger images here with the D800's 36MP, so yes, detail should be more noticeable, and so should image noise.
Down-sampling, or reducing the image resolution, will also have an impact on the perceived image noise in the D800's images, because it will look less prevalent at lower resolutions (which is why noisy digital photographs look less noisy when downsized for the web or when displayed on mobile phones). So when evaluating the D800's image noise, considering the final output resolution also plays a part. Not all users will be printing or displaying their images at the full 36MP resolution of 7360 x 4912, which works out to be an approximate maximum print size of 25 x 16 inches at 300dpi, or almost A2 size.
If we look at image noise based on the D800's full resolution, we'd say that images look good up to ISO3200, and noise is quite noticeable at ISO6400, which is the D800's native limit and the limit at which we'd shoot at to still get acceptable image quality. Depending on the output resolution, we might shoot up to the first boosted level of ISO12,800, but in general we would avoid shooting at the D800's highest setting of ISO25,600 as both luminance and color grain are quite obvious at that setting.
Digital cameras are always playing a balancing game between image noise and detail resolution. While the Canon 5D Mark III is quite aggressive with its noise reduction at higher ISO settings for JPEGs, resulting in cleaner images with less detail, the D800 seems to go lighter on the noise reduction, producing noiser images which retain more detail. Again though, the D800 is shooting at a higher 36MP resolution, if its images are down-sampled to the Mark III's 22MP resolution, image noise will be less noticeable and detail will still be retained. Even though the Mark III's JPEGs are softer, they're also cleaner which means they can be used straight out of the camera. In general, we found that the D800's images at high ISO settings will always benefit from a little bit of noise reduction applied in post.