Waterfall Photography & ND filters
I take quite a few waterfall/water shots with a slow shutter speed and have invested in an ND filter (ND4) in the hope i can have a slow shutter speed in brighter weather. Advice please on filter choice (i'm happy to but different filters) ,best aperture settings etc for this type of photography....anything really as i'm fairly new to using anything other than auto on camera (Nikon D40X)
I use a nd 4 to 8 both cokin p series If it is a bright day i use shutter mode anything from 2 to 4 seconds. If i use aperture mode i use anything fron F 11 to F22 iso 100 or lower
Your ND 4 filter is perfect.
To ge the best pictures you need to get shutter speds longer than one second.
to do this set the iso to 100, pu the camera on aperture priority and set an aperture of f22
the camera will then give its slowest shutter speed for the available light. If this isnt slow enough, then use the ND 4 filter as well.
a polariser will also reduce the light reaching the sensor by two stops and reduce glare, which my improve your water pictures.
because I now only have a ND32 filter so that's a filter that I always use for photographing waterfalls
but like MiddleMan say speed under 1 second is sufficient to soften the water flow.
and usually a good time to photograph waterfalls is in the morning and afternoon where the light is not too bright, so with CPL filter alone that reduce the 1-1 1 / 2 stop i can get speed 2-4 second
Polariser for waterfall photography
A polarising filter will really help as it will also cut out the reflections from the wet rocks, giving you more saturated colours. If you have two, you can use them on top of each other to have a makeshift variable neutral density filter. Be careful with wide-angle lens if you stack filters on top of each other, however. A cotton bag filled with dried beans or similar will serve as a cheap way to keep your camera steady.
Don't forget you can stack screw on filters too! I have 2 ND4 filters, with them both stacked I have gotten up to 4 seconds in late evening light. I mostly go for manual settings, once your ISO is kept down to 100-200, and you have figured the kind of length of exposure you can get away with, the only thing you need set is the aperture. It's as easy as using A priority, but you have that bit more control. i fond those semi-auto modes often get it wrong. You can see what A mode offers, then fine tune in manual.
Shooting Running Water
I agree that while exposures of under 1 second will work, I've optimally tried for 2-3 seconds.
Definitely look to shoot early or late. First, you'll get better light (and potentially some nice color off of wet rocks). Second, if your ND4 isn't dark enough, the early or late light will help compensate and allow you to get a longer exposure. Third, you'll likely minimize mottling from sun going through the trees and overexposing some elements of the scene (unless there are no trees near by).
Absolutely you'll need something to stabilize your camera. The tips about beanbags are good but I'd still prefer a very stable tripod that you hike in with. I know some shooters swear by using double polarizing filters but I've had mixed luck with that--really creating some colors that required a lot of post-production work.
ND4 plus early or late light should work just fine.