Cloud movement/blur and ND filter question...

[fiveoboy01]

If I'm wanting to get the blurred cloud look, what's a desirable exposure time, and I assume I'll need a ND filter(or several) to avoid overexposure?

What's your experience with this? Can ND filters be stacked if I want to add stops?

Or, what are the techniques for this look?

 

[Dao]

It's depends on the time when you take the photo. Windy day that cloud move quite fast around 7pm is different from Sunny/partly cloudy around noon time.

All you need is find out what EV you need on that scene. Then find out the time you need to smooth out the cloud with the ND filter added to obtain the same EV.


As for stacking filter, just need to watch out for vignetting.

 

[GeneralBenson]

A combination that I find the works, is having a 2 stop ND and a a CP filter. That gets you about 3.5 stops of a slower shutter speed than whatever you could other wise get. So I just point my camera out the window, and the sky is about 1/125th at f/11 and iso100. So 3.5 stops slower would get me about 1/10th at the same exposure. But it's a windless day and the clouds aren't moving at all. So I don't think that would be slow enough to be noticeable. But on a breezy, late afternoon, when the light is nice and a few stops lower, you could easilly get your shutter speeds down to 30 seconds or slower, between stopping down more and the lower ambient light. 30 seconds to a minute on a windy smooth clouded day would give you some nice silky clouds.