Back in the days of film, picture libraries and agencies required submissions to be on colour transparency film. This meant that all images had to be created in-camera with no opportunity for any changes to be made. This gave rise to the use of filters. Particularly to deal with contrast. With landscape photography there could often be a significant difference between the sky and the land, for example, and the way of dealing with this often involved the use of graduated filters.
The top picture and the following two were all taken on a Pentax 645 Medium Format film camera with a grad. grey filter attached.
I always found grad filters a pain to use. I had to carry around a holder, a collection of adapter rings for different lens threads plus a selection of filters, 1 stop, 2 stops etc. They slowed everything down somewhat. They were also made out of resin, attracted dust like a hoover and scratched very easily. However at the time, there wasn't much alternative. There's almost a genre of landscape photography created by them. I call it 1980's coffee table book landscape.
Since going digital I've stopped using them, preferring to use Photoshop to post-process and correct any contrast problems that way. There are a variety of ways to that. This is one of the simplest quickest and most effective.
By using the quick mask in Photoshop I lightened the houses and the cliff, using a curves preset, then reversed the mask and darkened the sky. So long as I don't lighten more than about a stop, there is virtually no noise generated.
I used the same process for the picture below.
I much prefer this to using grads., and its a good deal more flexible because of the straight line of the grad., which makes them useless if you have trees etc. against the sky. After practice I am able to to use the mask to carefully select the areas I want to alter, and because the mask has a very soft edge, it does usually give a natural look. Some pictures with grads., attached can be very artificial looking.
There's an article on filters by Ken Rockwell at http://www.kenrockwell.com/tech/filters.htm and while I wouldn't agree with everything he says, its a good read.
Words - D
Images - D & A