“Getting it right in the camera”, is a common phrase seems to contain an element of photography snobbery. It is critical to get the lighting and exposure and the fundamentals right, but unless you are a photojournalist, post processing is perfectly fine. Even in the “good old days” of shooting film, photographers have used the best tools they had to capture the look they were seeking. A set of those tools includes a wide range of on camera filters which can be used to control light, reduce glare, change the color of the image or just provide an extra layer of protection.
The first kind of filter is one that Roger and I disagree on how useful they are. Ultraviolet filters (UV) are advertised to serve 2 main purposes. Nr. 1 they are designed to block out extra UV rays from impacting your sensor. This was way more important back in the days of film, when intense UV could fog your film. Modern sensors reset each as you turn them on and off and as you press the shutter. The second reason and why I use them is that because they screw on to the end of your lenses, they provide a layer of protection from scratching, dust and general damage. I know from experience that they work, as I somehow accidently banged my 80-300 lens against a metal chair. The filter got badly scratched, but my expensive glass was fine. The argument against them is that you just spent thousands of dollars for an expensive lens, why would you want to put cheap glass in front of it; or I’ve never scratched a lens in my life. For the first one, the cost of the expensive glass is in getting the curvature and alignment right. UV filters are optically neutral and unless you are buying the $5 bargain bin versions, don’t impact the optics. As for the second argument, it will happen…just wait.
The next important type of filter is the circular polarizer. Most people are familiar with Ray Ban or Polaroid Sun glasses which help cut through the glare. What most folks don’t really understand is that light from the sun has direction to it. By controlling which light you allow through, you can cut down glare and reflection. Here is today’s science lesson showing how it works.
For shots with water on rocks or as one method to reduce the glare in an outdoor scene, you can adjust the direction of the light which passes through. Polarizers will effectively increase your fstop so you need to remember to take them off in low light situations. Gavin, over at http://www.fototripper.com graciously allowed me to use his image which illustrates the impact the right use of this filter can have.
He has written some great full blogs on how and when to use them and you should look at his landscapes, they are fantastic.
As a landscape photographer, this next filter is one of the most useful to have in your bag. Neutral Density Filters block part of the light from entering your lens. They can be graduated or solid—meaning part of the filter is darker on one end than the other. Why would you want to block light? Well, all those really silky, waterfalls or beach scenes with soft waves would have blown out skies if it weren’t for ND filters. These filters come in a range of densities from +1 stop all the way up to +10. Usually a filter holder is mounted to the front of your lens and you can easily adjust or remove them.
Just line up the gradient line with your horizon and you can use long, long shutter speeds. Here is what a sky looks like with and without a ND filter.
Finally, the last major class of filters also harkens back to the film days, especially for Black and White photography. I have to confess that you can replicate all of these in Photoshop or get similar impact by adjusting White Balances. Colored filters can emphasize or change the mood of your image. Two of the most common filters have pretty descriptive names. The Warming filter and the Cooling filter do exactly that. Here is a nice twilight photo from Ireland.
By applying the warming filter effect, it looks like a spectacular sunset—which it was not.
. If you apply the Cooling filter you get a just past sunrise look.
All of these are just tools, you still have to create the photograph.