I have often-times cursed the fact that I haven't purchased a set of Lee Graduated ND filters. These filters are used to help bring definition into the sky. Doing landscape photography is tricky because if you expose for the ground to bring the ground into proper exposure, you end up blowing out the sky and turning it featureless white or grey. If you focus for the sky, you get a silhouette for the landscape. So how do you expose both the ground and the sky at the same time and have them both turn out nicely. It involves getting some filters called Graduated ND filters.
There are two types: first the screw-on graduated neutral density filters which you cannot adjust for the horizon. and secondly; there are the various rectangular graduated ND filters that are created by either Cokin, Lee or other various companies. The ones that I intend to purchase are the 4x6 rectangular resin filters created by Lee. You can also turn around and do the ND graduated filter effect in Photoshop, however as most photographers would say, it's better to take a few seconds and get it right in camera, than sit down in front of a computer for a couple of hours and try to get the same effect.
These are available at various camera stores and I usually recommend The Camera Store in Calgary as they were the ones who provided me with the Lee Foundation Holder Kit which enables me to put the mount the holder onto my Nikon DX 18-70mm f/3.5-4.5 lens.
The adapter ring that goes on the 18-70mm lens
The holder that you can slide the 4x6 filter onto the lens. This is the basic filter set up. I will more than likely have to get the wide-angle filter holder when I pick up my 14-24mm f/2.8 lens (that's another purchase for another day)
When you put the adapter ring on the filter holder, you get this...
The filter holder attaches to the lens. It just slips on and you can rotate it depending on the horizon line. It is solid and snaps on and off your lens so that you can quickly get it in place. The 3-view is what the holder looks like on the 18-70mm f/3.5-4.5 which is residing on my wife's D90.
Doing landscape photography is fun. It's even more fun when you get a beautiful image. And to do so takes a little extra. The Lee filter system is that "little extra".