Schweeng!
Tilt and swing are the two movements on the large format camera that seem to cause people the most problems. I’m not sure if I learned quickly because I thought about it differently or because I’d already used a tilt shift lens on my 35mm camera but I have an explanation of the effects that don’t involve maths or mr Scheimpflug..
Basically it goes like this.. On a large format camera, you focus by moving the film place closer to or further away from the lens. If you want to focus on infinity, you move the film plane Xmm away from the lens (where X is your focal length). So on a 150mm length, you want to have 15cm between the lens and your film.
If you want to focus closer, you move the film plane further away from the lens.. This is how all cameras work (except in a 35mm camera, the movement generally goes on inside the lens body).
So… if we tilt the lens plane so that the bottom half of the film is closer to the lens than the top half, then the bottom half is focused closer to infinity. And thats that! All of the maths is just there to help you understand the relation between the tilt angle and the focus distances..
Swing is the same, if the left hand side of the film is further away from the lens than the right hand lens. Then the left side of the picture will be focused closer (actually it’s the right side because of things getting flipped.. you can see it on the ground glass anyway).
If you apply tilt and swing, you basically have a custom focus for each corner of the film… However working out how much combination isn’t particularly easy.
The example at the top of this post needed a little swing to help the top of the wall be in focus.. If it wasn’t for the wall, I could have just used some tilt and made sure the heather was in focus and the middle of the gulley was in focus (near the light trees). But because the focus spread close to the camera is a lot lower than the focus spread at infinity, the top of the wall will be out of focus (or need a very large aperture).
In order to minise this, I knew I needed to get the focal plan something like in the picture below.. To do this, I know I need to put about half of the angle that I have used for tilt into the swing, as seen below.
This was taken just outside our chalet in Clachaig.. the result isn’t that brilliant but it was a nice exercise.
