Hi folks~!
Any idea on this? Is the max load of a tripod determined by the tripod head only or tripod itself? All along I thought it was tripod head but 1 of the sales person from CP told me otherwise. ... thks~
Hi folks~!
Any idea on this? Is the max load of a tripod determined by the tripod head only or tripod itself? All along I thought it was tripod head but 1 of the sales person from CP told me otherwise. ... thks~
Which ever is the lesser. The weakest link is the one that will always break the system...
The strength of a chain is defined by its weakest link.
If the tripod can carry 10kg but the head only 3kg .. obvious, isn't it?
EOS
It's like asking to hold one's head, do u need a good neck or a good pair of legs? The answer is you need both. U need the neck to hold the head in place, but if one has weak legs, both the neck and head will be wobbly. If one has strong legs, but weak neck, one cannot hold it's head upright.
Thanks guys~...actually I using a Slik Sprint pro gm with the default SBH-100 ballhead. From the specs in slik website, it only indicate the max load for the ballhead but nothing for the Sprint Pro Gm...
http://www.slik.com/e/p10.jpg
http://www.slik.com/e/p17.jpg
I was at CP two weeks back. I was told that by the sales lady if the ballhead spec says 20kg,It meant sitting nicely at landscape position, 20kg is the max load. But if you decide to rotate the ball head to horizontal position which allows you to shoot portrait, the maximum that it will hold will be half, which theorotically makes sense.
So wouldn't it be better for you to get a ball head with a higher carrying limit than the tripod?
Yupz, that also 1 of the thing that the person mention to me as well... actually I only want to buy the ballhead but the sales person keeping "pushing" me to get a new tripod instead, saying my current tripod cannot take my setup (which is around 2kg plus) even if I upgrade the ballhead..
Even though I can't seem to find the max load for my tripod (w/o the ballhead) in the web, I think it should be much higher than the ballhead....so guess just upgrading the ballhead will helps..
Is it tripod of named origin? Any type / model? If not I wouldn't bet much on the load it can carry. Everything that comes free with a camera ('freebies') is rather to make the camera deal attractive. No shop has something to give away for free that actually costs money (because it's of quality).
EOS
think you can find the spec of the tripod here...
http://www.thkphoto.com/products/slik/slik-ss2.html
http://www.slik.com/cybersh2.html
Thks~. I using a Slik Sprint Pro Gm now. Yupz I have checked these websites before. It only indicate max load 2kg for the tripod with the SBH-100 ballhead..it never indicate any specs for without ballhead...
So not too sure if this mean that the max load for this tripod will depend on the ballhead.
Tripod - Max Load 4.4#
http://www.thkphoto.com/products/slik/slik-ss2b.html
Ballhead - Max Load 3.5#
http://www.microglobe.co.uk/catalog/...dshoot-cameras
From the look of it, your ball head is the weakest, can only take about 1.7KG. If ur setup is already 2KG, may need to should consider upgrading the tripod too.
The series is designated to "Digital and compact cameras" where 2kg is already exceptional load. I have the 340DX for traveling (with pan-head from 400DX) and when fully extended (4 segments) and loaded with camera, BG and some heavy lens it becomes susceptible to vibrations. The 400DX is rock stable, but weights a bit more. Personally I prefer pan-head. Feels more stable and gives me better control over adjustments.
EOS
Over loading, can cause a few failure modes to occur. Firstly additional deflection, second yielding, and finally fracture and it will break. If the manuf. rates it as 2Kg, I am quite sure it will withstand more, may be 20% more than that. So if u try to overload it by 10% the worst that can happen is that u may see a little higher displacement at the tip than usual. However, as the weight increase the COG also will be higher, and it will cause ur tripod to be unstable.
So do u really want to risk that?
it depends on your definition of max tripod load:
1) do you mean the max load the tripod can support as you can see in the spec of each tripod stated by its manufacturer.
2) or you mean the max load the combi of tripod & its head can support.
for (1)
max load of a tripod specified in the spec is the max load the tripod can support (safety factor already included) with no adverse effect on the stability with the legs fully extended but centre column in retracted position.
the load can be increase if use only extend, say the middle section of a 3 section tripod.
for (2)
Octarine has explained.
photography makes one sees things from all angles.
the legs can take 8.8lb of properly balance load
http://www.thkphoto.com/products/slik/slik-ss2.html
the sbh100 ballhead can take 3.5lb, as such, like Octarine explained, the original tripod & head can only take 3.5lb, less than 2kg.
thats why i change to giottos mh1303 that takes 4kg = 8.8lb,
so now it can take 4kg (tripod max load) - 0.17kg (weight of ballhead) = 3.8kg
photography makes one sees things from all angles.
Ok man.
Let me work it out for u,
First u have to understand a few things.
1. Force = Weight x Gravity (Newton), Here is the weight of the camera
2. Stress = Force / Area ( Pascal ) measurment of strength of the material
3. So here the stress will be the force acting on the smallest section of the ball head. where Area = Pi() * Radius^2
R^2 is the radius to the power of 2
Here in this case
First Position - Landscape.
The ball head is expected to be loaded in compression.
Therefore Stress Compression = F/A = F/PI() * R^2
Second Position - portrait.
The ball head is expected to be loaded in bending and direct shear.
Therefore Stress Bending = My/EI
As the Moment is very small, the length from the center of mass to the center of ball head is small Stress, so bending can be assume to be 0
and for Direct shear works like the one in compression Stress Shear = F/A
So if the allowable stress is the same
Thanwe get Sc = Ss which is the same...
Arh.... no getting any where hahaha...
Using Standards Allowable factor
but than if we include in the equation the industry standard stress ratio it will change the allowable stress factor ...
From standards,
Compression Stress Allowable = 0.6 * Allowable stress
and Shear Stress Allowable = 0.4 * Allowable Stress
SO........... we are getting somewhere
0.6:0.4 arh,,,, reduce the ratio to 1 we get 1: 0.666 so it is about half....
the Auntie is quite right.... my god she is good...
Conclusion
But than again we are not really sure if that is the way the ball head's max load is rated, acting in the landscape direction...
If i am the one doing it I will have just gone with the lower result as the maximum loads....
So no worries.
Last edited by jsprtan; 21st July 2010 at 11:19 AM.
jsprtan - Thank you
Looks chim.
For layman maybe as long as no displacement (creep) of the ball head (with camera body + lens attached) or
vibration on the tripod with the load(ball head + camera+lens) applied then good enough?
However when tilt the legs (say on a slope) then there is probably unequal weight distribution on each leg !
Some tripods can tilt the center column so the weight distribution on the legs will probably be different again.
So the best test is to try on the very worst case condition of all the various scenerios combined. And hopefully that
is also the manufacturer's specs for maximum load.
Wa, your math so solid! At least the auntie there is not doing sales like some electrical shops! Sometimes, it's hard to derive, but then this are some considerations for some beginners who are just starting to use tripods. Who could have think of that? Well... At least the Auntie was kind enough to provide a gentle reminder, instead of fast sales, hush hush payments
Bro,
I think what is call vibration here is actually the cycle loading and unloading of fingers acting on the shutter relaease. And if the damping coefficient is too small it will induce a longer decaying time for the force to die off.
The tripod plus the camera can be looked at as a lumped mass, alot of facters will affect the over all damping of the system.
1. The Center of Gravity of the whole system, this determine the theoretical height of the system. which affect the buckling loads or in laymen terms the displacement that u are likely to see. This the lower the better and whats affecting this is the weight and the center of gravity of each individual piece of equipment. Generally, the lighter the things higher up, the lower ur "COG" will be. And of course the weight of the tripod can also help to reduce this. Some tripod design a hook for u to hanging weight so to lower the COG. This too affect the wind tipping strength, which I am trying to work out for my set up.
2. Next The damping ratio of the set up, what will affect this is the material of construction, which cast material has always been excellent in this. And also The deisgn of the tel-legs and the natural frequnecy of the design, which mainly points to how much moment of inertia the legs will provide u. But this will also varies if the tripod is loaded or unloaded, for example a pluck sting in tension verses a loose string, u will see is also a difference in the decay time and this will varies with the amount of pull u apply. Once over tighten, the decay time will also reduce.
As for tilting, the weight distribution will depends on the position of the COG and the angle of deployment with respect to the gravitational pull. But I will believe, the camera maker will keep it as much as possible on the position that they have recommended u, which is either on or above the camera body screw or on the lens tripod ring. The fact that the distance horizontally aparts is very small, so i don't really thinks this will change the COG by alot horizontally. So it will be safe to assume that the weight distribution of all the 3 legs are quite equal at most conditions except if u set up the three legs at different angles.
So the best and the simplest is to bring in ur camera with the heaviest set up to test and doing the vibration test recommended by afew of the CS brothers.
Last edited by jsprtan; 23rd July 2010 at 11:34 AM.
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