Since I bought my D700 I have been trying, and mostly failing, to find ways to use its high ISO capability. It is certainly useful to be able to bump to 400 at times, and 800 in murky temperate waters, but I have not found many chances to go higher.
I had hoped that the German WW2 Frankenvald wreck, lying in 40m (deck 24-31m) in a Norwegian fjord might be a contender for higher ISOs when shooting with just available light. I shot the stern at a variety of ISOs 800, 1600, 3200, but in the end concluded that even in the dark depths of Norway, ISO 800 was the best compromise. At ISO 800 I shot the 15mm FE at f/7.1 at 1/40th (first image). I know I can hand hold available light wreck shots at 1/40th without blur and f/7.1 was plenty of depth of field for this type of subject. Higher ISO gave me a bit more shutter speed and depth of field - but these were not really noticeable in the images.
For close focus wide angle it is necessary to stop down a bit more, to ensure that the depth of field is adequate for the frame, there is plenty of light from strobes to achieve this. I continued on ISO 800, F14 @ 1/125.
So I am still struggling to find a real justification to push beyond ISO 800. But I'll keep searching.
For macro, of course, it is base ISO as normal. ISO 200, F25, 1/250th.
Alex
