Recently, a friend asked me to take a portrait of her in her office for professional use. We started behind the desk, but I didn’t feel that location captured her and the inviting warmth of her office and professional style. So we moved to a chair where she normally talks with clients, which was conveniently located by a window that let me avoid using a flash to maintain the natural feel of the office environment. I used a very fast lens (Tamron’s SP 35mm F/1.8) with a wide open aperture of F/2.2. This allowed me to capture my subject in sharp focus while blurring the background of the desk, laptop and books that let the viewer know the subject is in her office.
I find that the best way to make aperture-setting selections stick in your mind to be able to achieve a desired effect is to shoot sample images at two aperture extremes. Start by putting your camera into the aperture-priority mode (A on Nikon cameras; AV in Canon cameras). Then set your aperture to the widest setting (like F/2.8, F/3.5, etc.) and take a photo. This will be your sample A (see my sample below). Then move your aperture to its smallest setting (like F/22, F/32). This is your sample B. Then study the difference between the shots.
Now, to make things confusing, your results will vary depending on your widest aperture setting, focal length setting and how close you are to the subject. In my sample shots above, I was very close to the flowers I focused on and my aperture was F/2.8 in the first, so the brick building in the background is out of focus perhaps more so or less so than your sample shots may show.
If you keep making samples for yourself like this, eventually it will become second nature when you are shooting to select the appropriate aperture to get the photo you have in mind (with out of focus background or sharp background).
Typically you will want to blur the background a little for portraits for a more professional look; or if the background is very distracting; or if you want the viewers of your photos to be drawn to so a very specific part of the shot.
Photographers will use a smaller aperture to get the foreground to background in focus for landscapes, and sometimes for shots that tell a story of where you are. For example, you may want a store name to be in sharp focus so that it is legible. Or you may want the details of a landmark to be in sharp focus as well as your family standing in front of it.
However, sometimes landmarks, such as the Disney Castle, are so recognizable, that having the castle slightly out of focus works really well to give you a “here we are” shot that is elevated to a more professional looking image. Below is a sample from Epcot’s China Pavilion.
There are several ways to capture silhouettes. I find one of the easiest is to use your exposure compensation function, the same feature discussed in the previous post. The image above was shot at -2.0, under-exposing the image by two stops. The sky is a rich color, and the couple on the beach swing is completely black. Below, you will see variations of compensation (0, -1.0 -2.0 and -3.0) of the same scene. Next time you’re shooting around sunset, take several images of your subject that has strong identifiable lines at different exposure compensation settings until you find the one that best suits your vision.
There is a quick fix when you feel your photos are too dark. The +/- exp on the top of your camera lets you add or subtract light from the photo. This button is called the Exposure Compensation Button and is the fastest way to adjust the exposure of your image. Most cameras can do this in small stops of .33 at a time. Hold the button down while turning the wheel at your thumb (or forefinger depending on your camera model) and dial towards plus (+) to add light to the image if it is too dark and towards minus (-) to subtract light if the image is over-exposed.
Look at the first photo below. It was shot normal, no exposure compensation. Since the subject on the table was backlit by the window, the image is slightly dark. By adding a bit of light with the +/- button, I can brighten up the image.
The photo below shows a real difference at +1.33. I added more than I really normally would have for demonstration purposes so that you can see the difference.