DSLR Nikon FX vs. DX Noise
Some common mistake goes in the lines of:
- FX gathers twice as much light as DX.
Noise is exactly a pixel by pixel thing which most people simply can’t fathom. So FX is not gathering more light. It just has a larger imaging sensor which means you do not have to enlarge it as much to view or print. The noise is the same at a per pixel level (all else equal) but will be less visible since the picture is less enlarged. The exact same reason why a Medium Format camera shows less visible noise than FX all else equal when reviewed on a same sized screen or print.
This is also the reason that the D500 is superior to the D810 when the D810 is cropped to DX since the D500 has a better per pixel noise performance (according to Nikon themselves on par with the D5) than the D810. This makes perfect sense as the D500 incorporates newer technology.
So forget all the people who claims that FX gathers more light. It doesn’t! It is just a half misunderstood way of format chauvinism gone ape. FX only has an advantage because the sensor is bigger so lesser enlarged when viewing at normal size. View at 100% with the same pixel density and same generation technology and all should be equal.
Ok ok, so why is the D5 so much less noisy at 100% than the D500. You got it. Because it has a much less pixel dense sensor. Same with the D3 vs. D300. This is in fact Nikons way of having such success with their flagship FX cameras in terms of high ISO performance. They make them less pixel dense in order to be less noisy.
There will be the usual pack of people who will say that the FX gather more light but it simply isn’t true. The individual photo sensor gathers the same light no matter the format if the technology is same generation. Having a larger sensor area does not ‘magically’ gather more light per square inch. It just masks the noise at normal viewing-print size since each photosensors light gathering is not as enlarged to reach normal viewing size.
Science and physics is often brought into this but peoples misunderstandings and misrepresentations of scientific data is often grave.
Some pictures from DX and a couple from FX including some very high ISO shots with the D500. You figure out which are high ISO and what ISO your guess is welcome: