Technology has come a long way since I started shooting pictures with an old Kodak box camera. It was a Brownie box camera. It didn’t offer many options when it came to shooting pictures but I didn’t know that at the time. I held that camera at waist level and framed my shots through its crude viewfinder before squeezing the simple shutter release. No f/stops to adjust and no choice of shutter speeds. There was a bulb setting and I learned to use that to take time exposures when I learned to make use of the data sheet that came with each roll of Kodak 620 film. It was a simple camera but took great pictures for the nine-year-old photographer using it.
I had many cameras after that Kodak box camera; I haunted pawnshops buying one used camera after another, so I’m not sure which one was the first one where I had to focus the lens manually. What I do remember was how difficult it was at times to get a perfectly focused shot when shooting at night or in other low light situations. Like most photographers, I have come to rely heavily on auto-focus systems when shooting in low light or at night. For the most part the modern auto-focus lenses do a marvelous job but there are still times when they can use a little help from the photographer and it isn’t always in low light situations.
ï‚· There are many situations where the auto-focus system will want to constantly change the focus setting on your camera. For example, let’s say that you are shooting in an area where there’s a lot of pedestrian traffic i.e. a busy shopping mall. Your subject is sitting on a bench and relatively stationary but there are people constantly moving into and out of your shooting field of view and that will cause a big problem for most auto-focusing systems. The auto-focus system will continually change the focal point to follow the people moving around in the field of view. In a situation like this, the auto-focus system needs your help. Let the system focus on your subject and then manually lock the auto-focus system out so the focal point won’t wander as people come and go.
ï‚· When using auto-focus lenses make sure that the camera is actually focusing on what you want to be in sharp focus. This can be a serious problem when you are shooting with a wide-open lens, which means a very shallow depth of field. If you need to adjust the point on which your camera is focusing, hold the shutter release halfway down and move the camera around while the focusing light is on until it focuses on the area that you want in sharp focus. Some cameras have an auto-focus button that allows you to find focus points without risk of tripping the shutter accidentally.
ï‚· Most DSLR cameras allow you to change the area within the field of view on which it will focus ignoring the other areas. You customize the point on which your camera focuses by using its menu system and every camera’s menu system so all I’m going to say here is read your camera’s manual. Unlike with metering modes, most DSLR camera manuals go into in-depth instructions on how to change your camera’s auto-focus point.
ï‚· Every camera is slightly different and reacts differently to similar shooting conditions; even two Nikon D-40s have idiosyncrasies. That’s why professional photographers shoot hundreds of photos with a new camera before employing it to shoot a paying assignment. A few months ago I rented a Nikon D-90 body because I needed a third camera for a shoot and that camera made my life miserable because I didn’t have time to proof it before the actual shoot started. All I can say is thank the good Lord for the digital darkroom.
ï‚· Almost all DSLR cameras offer you a choice of two modes for auto-focus-SAF and CAF modes. SAF, Single-shot AF, locks down the auto focus and won’t let the shutter fire until the focus point has been confirmed. This is the mode we want to use for most shooting situations. CAF, continuous AF, mode allows the camera to continuously update it focus as the subject moves. This is a good mode to use when photographing fast pace sporting events or when photographing animals on the move. On more advanced DSLR cameras, Professional grade cameras, there’s a third auto-focus mode available, the hybrid mode. The hybrid mode allows the camera to decide whether it’s better to shoot in CAF or SAF modes. Once again, read your camera’s manual to find out what auto-focus modes are available on it and to learn how to switch between them
ï‚· Be on your guard against bright lights and light flares because they can confuse even the most sophisticated auto-focus systems. This is especially a problem when shooting nature where the most dramatic shots are made by shooting into the sun.
ï‚· Be cautious about using auto-focus when shooting close-ups because of the extremely narrow depth of field. I always switch to manual focus when shooting close-ups.
ï‚· Auto-focus systems work most efficiently with fast lenses like 2.8f or faster.
ï‚· Teleconverters used to extend the focal length of a given lens can play havoc with auto-focus because they reduce the amount of light reaching the focal plane. Some auto-focus lenses may not work at all with a Teleconverters so be careful when using Teleconverters.
ï‚· Give the auto-focus system the edge by starting the focusing process before you plan to take the actual shot. I use this method when shooting sports and animals. I follow the action with the camera, focusing constantly, even when I don’t plan to shoot. Doing that assures that my camera will be in focus and ready to shoot when I do trip the shutter release.
