Posted on August 28 2009
Focusing a lens was such a standard fundamental procedure to taking photos or shooting movies that it is difficult for those of us that grew up with this tradition to understand that today many filmmakers do not need or know how to focus. Good super8 filmmaking depends on good manual focus because super 8 predates good auto focus systems. Filmmakers need to spend some quality time understanding it, practicing it and learning when it is the most critical and when they could let their guard down. In the “good old days “a lot of photography was restricted to outdoors because of the slow ASA. Today you can have Super8 with 500 ASA so you can film in some pretty low light. This makes seeing focus more difficult. The original design of super8 cameras did not consider this. If you are going to get good super8 footage, you need to understand focus and depth of field, and practice.
To focus a camera with your eye, the system starts with the correct setting of the cameras internal diopter. Everyone’s’ vision is slightly different so the diopter in a camera calibrates your eye to what the camera is seeing. There are many methods prescribed for setting the diopter. I learned using the infinity approach. You set the focus ring of the lens on infinity and then looking at something far away, you focus the diopter to your eye. I then zoom the lens to wide angle and if it holds focus I’m set. There are numbers on every super8 lens that should correlate to the focus distance between the camera and the subject. These make great reference points to check if you are really getting the correct focus by “eyeing” it.
Most super8 cameras (except for Beaulieu) use a range focus systems. (Range Finder) This is not the easiest system to use and without the diopter set correctly , there is little chance of getting correct focus. The difficulty for modern super8 users is that when you look through the super8 camera you do not see all the information for focus. In particular, the F-stop or aperture and 85 filters are after where the focus optic is, so you do not see the effect this has on focus. In practical term this make the depth of focus constant no matter what F stop your shooting at in the viewfinder (what you see), while the depth of focus for the film will be radically different depending on what F Stop your at (what the film sees ) .
The other way to approach focus is to understand when it is critical and when its not. When you shoot at full telephoto, (the most zoomed in) and at full aperture (F the smallest number) on a big 10 to 1 super8 zoom the focus depth is less then an inch. This mean if your focus setting is wrong by even the slightest, or you move the camera as little as a few inches, you are out of focus. On the other extreme if you are at full wide on the zoom and the smallest aperture (F the largest number) the focus depth is huge, maybe 50 feet or greater. In this situation it almost doesn’t’ matter where you set the focus… you will be in focus.
Since most super8 film is shot in available light, you cannot change that. If you back off a little on that gorgeous lens to a wider setting and use slightly higher ASA film you will find focus to be much easier. At minimum, always make sure to vary your shoots wide and telephoto so even if you are wrong some of the time you have a chance of having some focused material. (c) Pro8mm ™ , Phil Vigeant 2009
Did you know there is an iphone app called PCam for the professional filmmaker? It calculates the imaging parameters of depth of field, hyper focal distance, and many others . The app supports Super 8 to 70mm Imax and numerous video configurations. – Rhonda www.pro8mm.com