On Thu, 17 Oct 2002 09:23:24 -0400, Grigorov, Boris wrote:
>I picked it up and made a very unscientific observation:
>I was holding the camera in my hands and suddenly cocked the shutter and
>then pressed the button. Then I did the same with the mirror locked in up
>position. It was amazing, to my senses, it felt that there is less
>vibration if the mirror is down and moving. It felt like the vibration it
>introduces was contained within the camera and absorbed by its inner
>workings. On the other hand, when the mirror was locked up, the feeling was
>definitely that of as if it were trying to move (the camera).
>Note that I used words like "feel" and "sense" to describe what I observed.
>Anyone has an explanation to this?
1) It is worth noting that the only vibration we're concerned with is that
which happens while the shutter is open. It can rock like the New madrid fault
before
and after as long as its doesn't move while the film is being exposed. Your
instruments may not have accurately isolated that particular time slice.
2) Related to the above, the primary vibration with the mirror locked up is
likely when the curtain supports hit the far side of the shutter opening - 1/2
of
which occurs after the shutter is closed.
3) With no mirror lockup, there are two sources of vibration, occurring in two
axes. Your instruments may not accurately isolate each axis and measure the
degree of movement. Further, the mirror motion, being prior to the opening of
the shutter had a higher likelihood of causing the camera to vibrate while the
shutter is open.
BB
--
Barry B. Bean
Bean & Bean Cotton Company
Peach Orchard, MO
www.beancotton.com
www.beanformissouri.org
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