Slice Vs. Sweet Spot
Let’s review a key difference between using a sweet spot and using a slice of focus. With a sweet spot optic you tilt the lens toward where you want the sharp focus. In contrast, with the Edge 80 the direction in which you tilt the lens is not influenced by where you want the slice of focus. Why not? Because the tilt only controls the orientation of the slice. The slice placement is controlled by focusing. For example, when you have a vertical slice (left or right tilt) you can position the slice anywhere in the viewfinder (from the far left to the far right) simply by turning the focusing ring on the lens.
Here’s a more technical tidbit: tilting left versus right (or up versus down) will not necessarily produce exactly the same slice of focus. This is because you have the lens at different angles and, depending on the angle of the lens to your subject, it could make a noticeable difference in your image. This is something you’ll just need to practice with.
In the next three photos a horizontal slice moves down through the image. Each composition is the same; the tilt of the lens was not changed between photos. I changed the position of the slice by adjusting the focus ring.
Excerpt from Lensbaby, 2e by Corey Hilz © 2012 Taylor & Francis Group. All Rights Reserved.