Viewfinder Parallax Marks

What are all those lines in the viewfinder?

What do those annoying lines in the viewfinder mean? Generally, there are three types of lines in the viewfinder. One set of lines tells you where the edge of the picture begins. Another set, seen on auto and manual focus SLR cameras, are the focus zone marks. Focus area marks are usually a circle and/or bracket box in the center of the viewing area. We won’t be dealing with those in this article. The others that look like notches or lines across the top of the viewing area are called parallax marks or lines. (See fig. 1,2 and 3 for examples)

Figure 1
Figure 1
Figure 2
Figure 2
Figure 3
Figure 3

The lines around the outside border or at the corners mark the outside edge of the picture. Some viewfinders have them and some don’t. They frequently are not an accurate indicator of the “exact edge” of the picture. Some viewfinders only show 85-95% of the real image in the entire viewfinder. Hopefully your camera manual says how much of the real picture area is covered by the viewfinder on your camera. The things to watch for are things just barely outside the viewfinder’s view. All sorts of stuff can end up in the picture that wasn’t in the viewfinder when you took the picture. Things like a diver’s fin, coral and sponge parts, and even halves of divers have mysteriously appeared along the edges of images that were never seen in the viewfinder. On the good side, the photographer is less likely to cut off part of the image that he/she wanted to take.

You won’t see parallax marks in an SLR camera viewfinder, because an SLR doesn’t need them. SLR camera viewfinders see what the lens is seeing. When an external viewfinder is seeing a slightly different picture than the lens is seeing, that’s called parallax error (See fig. 4). The parallax marks come in handy for compensating for that difference.

Figure 4
Figure 4

External viewfinders are slightly tilted downward toward the camera lens. The view of the viewfinder and the lens converge at about three apparent feet (four measured feet). When you try to take a picture closer than three apparent feet, you start progressively cutting off the top of the image. The loss of space at the top of the image happens progressively. The closer you get, the bigger the difference between what the lens is seeing and what you’re seeing through the viewfinder. Parallax marks are most useful in wide-angle close-up photography. The parallax marks tell you where the “new” top of the image should be at that distance. If you’re shooting at a distance other than the distance for the mark, you just have to make it your best guess. The newer viewfinder for the Nikonos 15mm lens has two parallax marks, one and two apparent feet. Most viewfinders have only one distance marked. The parallax marks force you to tilt the camera up a little, which in turn reduce the parallax error inherent in the external viewfinder system.

Parallax marks and the other lines in the viewfinder can be useful guides. Don’t look “past” them the next time you’re in the water; consider what they are trying to tell you.

DIVING IN DEPTH TAGS

  • focus marks in the viewfinder