In Guadalupe the capabilities of the D3 at ISOs 400-800 were very valuable. Particularly early and late in the day, when the light is often most interesting. My buddy, shooting a D200 definitely found those conditions much tougher. Another advantage of high ISO was being able to use low flash powers, which meant that I could use the camera on continuous low (4-5 frames per second) shooting. Continuous high produces up a ridiculous 11 frames per second. This enabled me to produce a series of shots from a single pass. I also shot some images at ISO 1600 and the noise was much more noticeable in the blues. In the middle of the day I was shooting at ISO 200. In brighter tropical waters I doubt I would find many uses for ISOs above this.
The high ISO capabilities of the D3 are revolutionary for the Nikon shooter and allow you to produce types of underwater images that would be impossible. However, these capabilities only come to the fore the right conditions. If you dive entirely in tropical conditions or shoot macro such abilities will rarely be of any use.
The D3 can record RAW files at a bit-depth of 14-bit and perhaps equally important is Nikon’s Active D-Lighting, which is a bit like an in camera Shadows and Highlights, and is applied to the RAW file. Both of which promise better dynamic range for digital files. The big question remains is the D3 the camera to finally capture sunbursts just as they look on a tranny on a lightbox? No, is the short answer. I felt it was better than the DX cameras I was shooting alongside, but I would find this impossible to quantify with the real world shooting we did. I certainly do not feel that there is a day and night difference between the D3 and its 12-bit predecessors and I don’t have any shots that can demonstrate it.
At times in Canada the D3 really struggled with the transition from the bright surface to the inky depths. In the blue water of Guadalupe is coped much better and I was much happier with how it recorded afternoon sunrays. These seemed to be a benefit for macro too. I shot several subjects amongst the bright while plumose anemones and I was very impressed with how the D3 coped with these scenes.
But that is all just opinion. Without some controlled conditions testing the different to 12-bit cameras is so small as to be difficult to discern. In conclusion, I have absolutely no complaints with the D3 image quality, which is as good as any underwater camera I have seen. But get feeling I don’t think I could prove to anyone it is any better.