At 01:02 5/24/01, Dr. Oben Candemir wrote:
John,
Correct me if I am wrong; but I feel that the increased standoff distance
at the same magification would increase the effect of camera shake. The
reason being that the same amount of "angular" movement of the camera
translates to a greater linear distance when the subject is further away.
To see what I mean draw a triangle with the same angle.... the height
increases the longer the base is.
So using a 90mm f2 at 0.5x and a 50mm f2 at 0.5x gives you different
standoffs... but my reasoning would say that the 50mm f2 has less camera
shake effect than the 90.
Your views?
Hmmmm, you made me _think_ about this again. OK . . . if I got the thought
experiment correctly:
You're correct if the _only_ shake component is rotational about the film
plane affecting only the direction the lens axis is aimed. However, and
this is what I was thinking, shake is 3-dimensional with a translation in
x, y and z axes. Any shake of the camera body in x-y axes will have the
same effect so long as magnification remains the same. Actually it's some
combination of the two, meaning you can reduce the effect of rotational
motion (about the film plane) with a shorter lens, but not x-y translation
of the lens axis. (Of course, there is a z-axis issue also shifting
magnification and DOF, if it's extremely shallow).
In my experience, the problem with non-macros is mostly rotational. In
macros (.25X and higher), the translational becomes significant; the higher
the magnification, the more significant. Thus, my conclusion (and
experience) has been that you cannot get away from shake issues with a
shorter lens and moving closer. Anyone elses thoughts and experience on
this are appreciated.
-- John
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