Can't help with an exact on the strobe, but you'll notice considerable fall off at six or so feet.
Yes, the environmental conditions can make a huge difference in the blues. Some of the nicest blues I've gotten are from overcast days! I've had to drop to 1/100 or 1/125 on overcast days - but I have only shot UP so if I should straight or down I'd likely have to fiddle again!
Also, some water simply isn't blue. You might even see it as blue, but it is more grey or green. The only thing for that is Photoshop if you don't like the "natural" look.
Yes, the environmental conditions can make a huge difference in the blues. Some of the nicest blues I've gotten are from overcast days! I've had to drop to 1/100 or 1/125 on overcast days - but I have only shot UP so if I should straight or down I'd likely have to fiddle again!
Also, some water simply isn't blue. You might even see it as blue, but it is more grey or green. The only thing for that is Photoshop if you don't like the "natural" look.