400mm Its my birding lens.
Nice shot your D-90 shoots RAW have you tried that yet? I've found its the best for underwater.
You can correct the Kelvin Temperature easy.
I'm using RAW for everything now but back it up with a basic jpeg to view editing quickly.
So what I'm saying is i shoot two simultaneous images, one is jpeg basic just to see what i have shot in a edit mode and the other is RAW format, the real thing i make my photo from.
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