Graduated ND Filters

theusher · Mar 26, 2007

I am interested in graduated ND filter. I've seen a lot of comments that the round ones are pretty much useless and you need to go with the square ones. I have no experience with the square holders and stuff, so I was hoping to hear some opinions...(I assume they have them for the D80)

Maybe it's possible without the filter to get the same effect?

Big Mike · Mar 26, 2007

I agree, the square ones are much more versatile than the round ones.

With square filters, you need to get a 'holder' which fits onto the front of the lens and holds the filter. You will need to get a holder, or a holder mounting ring that matches the front threads of your lens (the camera makes no difference, it's the lens threads that you have to match).

The system that I have is the Cokin A system. Cokin also has a P system and an X system...the difference is the size of the holder and size of the actual filters. If you use very wide angle lenses, you will want/need a bigger filter.

Once you have the holder and the filter, it's easy to use. Just slide the filter into the holder and adjust it so that the dark/light transition matches your composition.

You can get the same effect in photoshop, but the advantage of using a filter is that you can get a better image to start with. Cameras can only capture a limited range of tones, in one exposure, before the detail is lost. By using a split/grad filter, you darken the brightest areas so that you can capture more detail in areas that would otherwise be blown out etc.

Another way to get a similar effect is to just take multiple exposures (with a tripod etc) at different exposure levels and then combine them in photoshop. This method is sometimes called HDR (high dynamic range). You can get great results this way, and it's more flexible than using a filter...but it can also be a lot of work, requiring good photoshop skill.

theusher · Mar 26, 2007

Yeah, I didn't even think of going with the multiple exposures. Thanks for clarifying how the square filters work. I'm definitely going to look into that.

250Gimp · Mar 26, 2007

I have been thinking about a Graduated ND filter myself. Why are the circular ones no good? THat is the type I was thinking of going with.

Big Mike · Mar 26, 2007

Why are the circular ones no good?

Because the transition is right in the middle of the lens...which limits your composition (and usually putting the horizon in the middle is a poor composition). With a square filter, you can slide it up or down in the holder and move the transition to fit your composition.