Which level ND filter?

[lfc1892]

Hi folks. I want to get a filter to fit my Cokin P series holder but not sure what level density to go for. I use a NIkon d5000 and maximum exposure time is 30 sec. I have no idea how long exposure times can get with really dark filters so can somebody please recommend how dark I can go? It's mainly to get some cloud movement etc in landscapes. Many thanks in advance.

 

[HoppyUK]

The really dark NDs need to be sealed against the lens, or scewed in, to prevent light leaks, so the P-system is not ideal.

The density you need depends on the ambient light level and the shutter speed required, and the shutter speed for clouds depends on how windy it is. So no hard and fast answers. Having said that, clouds need longer than most things so you'll probably need a darker one, like 8-10 stops.

 

[lfc1892]

Thanks for the advice. Will plump for a screw in type.

 

[markmullen]

The maximum settable shutter speed will be 30 seconds but you should have a bulb setting which will allow you to keep the shutter open as long as you want (up to minutes or hours).

 

[lfc1892]

Thanks for the advice.