[LRflex] Re: Table-top Macro Work.
- From: Philippe Amard <phamard@xxxxxxxxxxxxxx>
- To: leicareflex@xxxxxxxxxxxxx
- Date: Tue, 09 Jan 2007 17:33:29 +0100
Thanks Charlie.
Your contribution was very informative.
And if I may try to summarize it all, we should end up with a
contraption of a large and heavy rock resting on sand, supporting a
spring footed composite tripod of which one triangular leg element would
be made of wood, and stabilized with bags of a mixture of sand and lead
hanging from rubber tyres. (Have I forgotten anything?). :-D
Just the idea of it pleases me, it does. I don't know if I'll have the
courage to build one some day, but it might be worth the try for the
Guiness Book too.
Slaint !
Boyishly
Phileicangemix.
chfalke@xxxxxxx wrote:
>Douglas, Philippe,
> I'm not a physicist, but a mechanical engineer. The spring
>system would isolate the suspended table from inputs from
>the ground, such as the little earthquakes caused by passing
>cars. Isolation means that the springs are soft compared to
>the suspended mass. (In engineers' terms the natural frequency
>of the table/spring system is lower than the exciting frequency.)
> In this case the subject and the camera would both need
>to be on the table.
> The things you want a tripod to do, as a rule, are not to deflect
>in response to disturbing forces, and to damp out quickly.
>High stiffness (metal) reduces deflection, but some metal has
>relatively low damping, meaning it springs back. Wood has
>higher damping, but enough wood will be better, which is why
>you see it used in tripods for surveyors' transits.
> Composite is very stiff and has can be made with high
>damping ratio, which is why it's worth the bucks.
> We tend to use "rigidity" to mean stiffness and high
>damping both, and sometimes also a structural design
>that favors more system stiffness for a given mass,
>such as tripods with cross bracing, wide section legs, and
>legs that have triangular form.
> So the following are good, composite, wood, (metal if there is
>enough relative to camera weight), centerpost down, and
>leg extensions retracted so that point of the the triangular part of the leg
>is close to the ground. A Graflex Crown #2 is pretty good
>if it's sound. Metal Gitzo's are good, too. I think they must use
>an alloy with high damping.
>Hope this helps.
>Charlie.
>
>---- Douglas Sharp <douglas.sharp@xxxxxx> wrote:
>
>
>>I'm not sure, Philippe ? A rigid system would be less prone to higher
>>
>>
>------
>Unsubscribe or change to/from Digest Mode at:
> http://www3.telus.net/~telyt/lrflex.htm
>Archives are at:
> //www.freelists.org/archives/leicareflex/
>
>
>
------
Unsubscribe or change to/from Digest Mode at:
http://www3.telus.net/~telyt/lrflex.htm
Archives are at:
//www.freelists.org/archives/leicareflex/
Other related posts:
