Stops?

[Photowilf]

Hey I'm looking for a filter to under expose my photos, I want to use it for slow shutter speed to blur water movement and obviously I need a filter to prevent over exposure, we all know how annoying that can be, and I don't know whether I need a 2 stop, 3 stop or even higher stop filter, I intend to use about a 1-2 second shutter speed. Do I even need a filter or is there another way, such as a smaller aperture would that work? Any help?

 

[TCR4x4]

It all depends on the light you are shooting in.

For blurring water, a 3 stop will do it in overcast light. If its 30 degrees centigrade and bright sunshine, chances are you will need more.

Use the lowest ISO you can and the narrowist aperture you can. (f/11 or higher, but beware of diffraction kicking in above that)

The most popular is a 10 stop, but that will give you shutter speeds of 10-30 seconds and more.

 

[DoctorBob]

Go to what you want to photograph and take a photo with the aperture setting as you want, ISO to the lowest, and let the camera handle the shutter speed. Then figure out how much slower you want the shutter speed to be, and voila! - that's how many stops your ND filter needs to be.