Chuck Norcutt wrote:
> Yes, you have it. Another point of interest is that supposedly (I don't
> know where to find it on Oly documents) Olympus always recommended
> placing the hands on the camera and pressing down when firing the camera
> on a tripod.
Every eSIF lens entry from the 85/2 on up in focal length says:
"Also, to prevent camera shake: When using a tripod, hold the camera
steady with both hands and press the shutter release with the ball of
finger, not with the cable release."
Why they put it there and not in the instruction sheets is a mystery to me.
> Good advice since the pressure and flesh of the hands is a
> good vibration damper. I believe Walt also carries a small bag of lead
> shot to drape over the camera which has a similar effect and allows the
> hands to be free.
>
> To the best of my knowledge Gary never did any testing with any of these
> other methods.
He said he didn't use Oly's suggested "wetware damping" technique
because of the impossibility of scientific repeatability. I suppose the
sand/shot/whatever damping bags just didn't occur to him. His tests are
a unique and invaluable resource, but not perfect. He has later said
that his 50/2 test somehow underrated wide aperture performance. And
also that his 400+ mm Zuiko tests didn't adequately address vibration
issues; with adequate vibration control he has since seen that they are
sharper than his tests indicated.
He didn't follow up with further tests after he ran out of his test film
and it had been discontinued on the grounds of incompatibility of
results with a different film.
> It would be interesting to know, for example, if we
> really need to use Walt's heavy bag of shot or is a simple, one pound or
> 1/2 kilo bag of dried beans sufficient?
Weight isn't the only factor. I think internal friction and mechanical
coupling to the items being damped are also important. I don't think
beans, for example would be very good because of their relatively large
size, smooth surface, low contact areas and relatively low density. I
believe Walt uses birdshot, rather than larger shot and I imagine sand
would work better than the same weight of beans.
> Maybe a plastic zip-lock bag which can be filled with sand or pebbles on
> location?
>
Bag material might make a difference too. A slippery zip-lock might
couple to the camera/lens less well than a more flexible and rougher
textured fabric, for example. Weight alone reduces amplitude of
vibration from any given impact, but conversion of vibration to heat
energy by absorption, primarily, I think, through friction, is more
important in this application.
Moose
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