><< I've always thought a person was supposed to use
> the hole at which the lens/camera naturally balanced, but Gary
> enlightened me, explaining that using an UNBALANCED mounting point would
> lessen the effect of vibrations. Makes sense to me, now that I think
> about it. >>
>
> Can someone explain it to me, so it makes sense?
> George S.
I'll take a crack at it, George, since I was the author of the
incomprehensible jibberish above. Let me try again. As you know, many
Zuiko teles & zooms have tripod collars: rotating, but lockable collars
(with a "foot" where the 1/4 by 20 threaded stud of the tripod can be
attached). My 300mm has one of these, but with a single mounting hole in
the short "foot." The 250mm, on the other hand, has a long, maybe 6 to
8-inch "foot" with not one but four threaded holes drilled in it. The
idea of multiple holes, I had assumed, was to allow the photographer to
use the hole that acted as a natural fulcrum to the lens/body
combination. I thought it was best to attach the body to the lens, turn
the lens/body assembly upside-down, put a couple of fingers under the
"foot," and see where the whole assembly balanced in the hand. Whichever
hole was closest to that balance point, I used for mounting to the
tripod. This was usually the *third* screwhole on the foot (counting from
the body). But what Gary taught me is that it's better NOT to use the
balance point, allowing the imbalanced weight of the body/lens assembly
to counter vibrations. Gary attaches the assembly to the *first*
screwhole (counting from the body), so that the mass of the lens is
forward from the attachment point. (So that, if the tripod stud gave way,
or you hadn't locked down the tripod head, the lens would immediately
pitch forward onto its objective! But let's not imagine that.) This
additional tension at the point of contact with the tripod, the
unbalanced weight, should help damp unwanted vibrations that would be
more likely to occur in a balanced setup. After thinking this through, it
makes perfect sense to me. Imagine a perfectly balanced compass needle.
Tapping the compass causes the needle to jiggle. Now imagine if that
needle weren't balanced, if there were more needle mass on the "N" part
and less on the "S". The compass wouldn't swivel as freely, and wouldn't
jiggle as much if you tapped the compass. The compass probably wouldn't
work at all, but the needle would be less prone to vibration! A bad
attribute for a compass but a good one for a lens on a tripod.
PS: Thanks for your insights re the IS-10!
================================================================
Kelton Rhoads, Ph.D. kelton@xxxxxxxxxxxxxxxxxxx
================================================================
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|