On Wed, Oct 12, 2011 at 6:25 PM, Chris Trask <christrask@xxxxxxxxxxxxx>wrote:
> >
> > An interesting article regarding tripods was brought up in another group.
> > http://www.berlebach.de/anleitungen/91.pdf
> >
> > also http://www.berlebach.de/anleitungen/52.pdf
> >
> > I can't help but wonder if "the stands extracted to one third of the
> maximum
> > length and loaded with 70% of their working load" wasn't chosen to give
> the
> > wooden tripods the best performance. Who carries a tripod that is tall
> > enough to use at one third its length? I would think that the length
> would
> > have a dramatic influence on resonant frequency (but hopefully your
> tripod
> > isn't a musical instrument).
> >
>
> The tripod shown on the second page of the first document is an
> impressive piece of hardware. I'm a bit surprised that the tripods with
> solid cross-section legs would fare better than those with hollow metal
> legs, as the hollow legs have more surface area (inside and outside) and
> should dampen out vibrations more quickly. I wonder if the head assembly
> or
> accessory shelf might be part of the problem.
>
> When reading opinons on tripods in various nature photography books,
> most authors did not desire leg braces as they made the tripod placement
> difficult on uneven surfaces. From an engineering standpoint, leg braces
> should reduce the vibration problem, at least at lower vibration
> frequencies. I have a somewhat heavy Manfrotto 3001 which does not have
> braces, as well as a much lighter Ambico V552 which does have braces.
> Neither one has shown any noticable vibration problems.
>
> But, both of these documents are discussing tripods for fairly heavy
> astronomical telescopes where very long exposure times are an issue, so any
> tendency towards virvration would be a problem for astrophotography.
>
> Chris
>
Hi Chris,
I had been very happy with a lightweight Gitzo CF tripod for several years.
I mounted a Zuiko 1000mm on it in a windy location. The image bounced around
so much it was difficult to frame the scene without holding the camera still
with my hand. The same tripod had previously routinely given excellent
results with a 400/4 Tamron + 1.4x teleconverter. I've never understood why
the results were so very dramatically different.
Recently I mounted a 500/4 cat lens on my new heavier CF tripod. With 10x
live view I again saw more movement than I am willing to accept. I think the
problem this time was the geared head I was using. I'm going to try again
with the Acratech ball head I've been very happy with.
Your mention of the braces between the legs gives me something to think
about. The main thing I started wondering about due to the article was that
a twin-shank leg(typical of a wood tripod) would be much more resistant to
twisting about the center axis of the tripod.
Interesting coincidence with respect to your Manfrotto 3001. I have a Sinar
P mounted on top of a 3001 while "stored". The 3001 was never intended to
handle something like a Sinar P, so it is terrible abuse of it. Very little
force is required to get it dancing around.
Thank you for your comments. That will give me more to think about.
Jeff
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