ND Filter

[Graemey]

Hello All,

I'm interested in buying a ND Filter but not too sure which one. Is there a difference between a Grad filter and a ND Filter? I have been reading about a Cokin P153 Neutral Density x4 Filter, is that any good?

Thank you,

Best wishes
Graeme

[scootermcq]

Hey Graeme, a grad flilter is darker at the top and less dark at the bottom (graduated), so when taking a picture the sky is less exposed that the dark grass or trees. An ND filter is simply darker all the way through. The numbers refer to the amount of stops it will remove. Therefore an ND4 will remove 4 stops of light. They both have their places, but are definately different. I have not used the filter in question

[Elmo]

An ND filter reduces the light for the whole image Like when you need to shoot wide open in bright sun or to give slower shutter speeds for water flow shots. A GRAD is half clear and the other half dark with a transition area between the two. These are used primarily to limit over exposed skys.

I have some very old Cokin Filters that are ok but I recently bought a new one and it gives a color shift that I find almost impossible to correct.

[sk66]

With todays ability to combine/edit images I find almost no use for a graduated ND. Even if you do have use for one there are usually issues in implementation (getting the transition to line up well w/ everything).

ND's are nice for getting long exposures when there is too much light... Instead of buying a selection of them I bought a variable ND and have been quite happy with it.

[rosserx]

ND's are nice to have in your bag for when you're trepsing through the woods and happen upon a waterfall or running stream and you want to get that "silky glass" look.

[inkista]

Originally Posted by scootermcq

An ND filter is simply darker all the way through. The numbers refer to the amount of stops it will remove. Therefore an ND4 will remove 4 stops of light....

I'd actually say, always read the description to be sure how many stops the filter goes. Different manufacturers number their NDs differently. A lot of them give the number for the "darkening factor", rather than the effective stops. E.g., a Nikon ND4 is actually a 2-stop filter, because the 4 is the darkening factor (4x darker). Remember, stops are a doubling scale. 4x = 2 stops, 8x = 3 stops, 16x = 4 stops. If it's the "x" notation, do a log₂ to find the stops.

A lot of other filter manufacturers (Lee, Hoya, B+W) use a density number/third-stop scale, where each 0.1 is a third of a stop. So, a 0.3 is 1-stop, 0.6 = 2 stops, 0.9 = 3 stops, and 3.0 = 10 stops. That's why a B+W four-stop ND filter is described as a 1.2 filter.

BTW, I just found the graduated ND thingie in Lightroom. I feel so stupid not to have played with that before, given RAW's capability of recovering detail from highlights...

[sk66]

Originally Posted by inkista

BTW, I just found the graduated ND thingie in Lightroom. I feel so stupid not to have played with that before, given RAW's capability of recovering detail from highlights...

Yeah, that (and similar in other products) is why I say Grads generally are not worth the money/hassle anymore.