At 22:14 5/23/01, I wrote:
You're correct if the _only_ shake component is rotational about the film
plane affecting only the direction the lens axis is aimed.
Should qualify this . . . rotation around a line lying in the film
plane. Rotation of the film plane around an axis perpendicular (or
normal), such as the lens axis, will have the same effect at the same
magnification, regardless of focal length. There's not just two
components, a better way to describe it is with four:
1. Pitch and yaw for which a shorter focal length reduces the effect.
2. Roll the effect for which stays the same.
3. X-y translation of lens axis the effect for which stays the same.
4. Z translation of the film plane along lens axis, for which a shift in
DOF will not change, but for which a shorter focal length will increase
effect of magnification change.
My conclusion . . . you cannot escape or reduce the issue significantly in
practical terms by going longer or shorter . . . remains the same.
-- John
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