Using a spot meter for landscape photography

For many learning photographers the subject of exposure can be intimidating, or at least difficult to grasp. It is in fact an extremely simple concept. The difficulty lies in understanding the lighting situation you face and learning to make the correct decisions. Of course, automatic matrix exposure systems make even the most complicated lighting situation (e.g. wide contrast of light and dark within a scene) a “walk in the park” when wanting to render the scene correctly. But this is where the problem is. What is the correct exposure? Camera manufacturers spend years of development research to come up with ever more advanced exposure meters with complex computers built in to make that decision – what your exposure should be. Whilst such auto exposure meters are superb nowadays, there are situations where they are next to useless unless you can access their manual overrides, or even better, their spot meter mode. Why? Because ultimately, the photographer is the one who is creating the photograph, not the computer. The computer won’t know that you want to emphasise the shaft of light coming through the window, with deep black all around it. The computer will only see bright light and darkness and try to find the “middle” ground. What you have is a weakened exposure. What ought to be black will have unwanted shadow detail, and the details in the shaft of light will be too light. The computer takes over as author of your photograph, and this is wrong!

Exposure of light to film is not just a technical exercise and choice, but it is ultimately a creative one. You photograph a sunset at different exposures and you will get a radically different effect, none particularly wrong, but will hold a different emphasis and feel. A yellowish sunset will go very orange or red if you “under” expose. A decision you have made in exposure changes the final outcome of the image, for many unwittingly.

I am not going to try and explain how exposure works, i.e. the relationship between aperture, shutter and film speed. But for those who have a basic grasp of exposure I would like to advise you to look at using the “spot meter”. There are devices which are solely spot meters, and I use a Pentax digital spot meter which takes a 1 degree reading. In other words, I can take a reflected light reading from a minute area of the scene. If I take a light reading from every part of the image I know exactly what will happen to my final photograph based on my choice of exposure. There will far less chance of any nasty surprises when seeing the resulting image! Of course, I am speaking of film. With digital one can take and retake many exposures through “bracketing”. But sometimes, even then, you can misinterpret what result you are seeing on the small viewfinder of the camera with what you actually captured. Many digital cameras have spot meter modes, so why not use it? To be sure, a spot meter is the most effective method of working out exposure in landscape photography. A fine example that explores these principals is through Ansel Adam’s renowned Zone system. This system can be applied to colour, not just black and white.

Perhaps one of the most useful reasons for using a spot meter is to assess what strength neutral density filters are needed to balance out contrast in the scene. If the contrast is too high, then neither film or digital can cope with it. The most typical example of high contrast is when the foreground is much darker than the sky. Again, I am not going to get technical, but you generally have only 5 stops to work with when considering your exposure starting from the “average”. By saying that, I may have lost the majority of those reading this. Don’t worry. As a rule of thumb, if you are taking a scene with sky and foreground in it, your image will almost certainly benefit from a neutral density filter. Such a filter has half of it “painted” with a tint, like sunglasses if you will! It stops some light getting into the upper half of the image, thus balancing out the bright light of the sky with the darker foreground, resulting in an image that is well exposued. No automatic exposure meter has yet been able to duplicate this effect (although I would anticipate this happening one day!). A collection of different strength neutral density filters is standard essential kit for any professional landscape photographer. It makes or breaks a superb image. If you can only afford one filter, buy this one!

If you want a more thorough treatment on either exposure or use of a spot meter then please comment on this blog and I will do my best to explain the principals in layman’s terms, using practical working examples.