Tripod Apex question

[basker]

I understand that tripod apex hinge size affects stability.

Does the spacing from centerline to hinges matter?

Thank you,

Sam

[Les Olson]

If you imagine the triangle formed by any two of the tripod legs extended up beyond the hinges, the closer the mass of the ballhead + camera + lens is to being inside that triangle, the more stable the tripod.  So, the further the hinges are from the centre, the higher the apex of the imaginary triangle, and the more of the load is inside the triangle.  The downside is that the plate that the hinges attach to has to be stronger and therefore heavier. 

The alternative way to get the centre of mass inside the triangle is to hang a weight inside the tripod.

I do not think that tripod hinge size does anything independently of the diameter of the tripod legs.  Thicker legs require thicker hinges, and thicker legs are more rigid.

[David H. Hartman]

The alternative way to get the centre of mass inside the triangle is to hang a weight inside the tripod.

I do not think that tripod hinge size does anything independently of the diameter of the tripod legs.  Thicker legs require thicker hinges, and thicker legs are more rigid.

I'm not sure about hanging weight as it can swing causing its own problems but the flexibility of smallest or lowest legs of a tripod are easily a tripod's achilles heel. I own an original C. M. Marchioni Tiltall and Bogen 3021 that suffer this way. I guess they are good to about 135mm.

When I was really green. I tried to use the Tiltall with a 600/9.0 Vivitar Series 1. I thought the lens was a dog. 

My Nikon F3 and later performed much better my Nikon F2As, FM2n and FE2. The latter show more vibration on mirror up and shutter open on the tripods with more flexible lower legs. Not using the last tripod section helps quite a bit and spreading the legs of the 3021 helps even more.

Dave Hartman

[basker]

If you imagine the triangle formed by any two of the tripod legs extended up beyond the hinges...
I do not think that tripod hinge size does anything independently of the diameter of the tripod legs...

Les,
Looking at the RRS apex conversion kit, I became fixated on a stability question that I could not answer. Thanks for helping me break out.
Looking at my tripod as three pairs of legs instead of just three legs is a clear and quite interesting concept. Your posts give me wider perspective.
Sam

[Asle F]

If you imagine the triangle formed by any two of the tripod legs extended up beyond the hinges, the closer the mass of the ballhead + camera + lens is to being inside that triangle, the more stable the tripod.  So, the further the hinges are from the centre, the higher the apex of the imaginary triangle, and the more of the load is inside the triangle.  The downside is that the plate that the hinges attach to has to be stronger and therefore heavier. 

The alternative way to get the centre of mass inside the triangle is to hang a weight inside the tripod.

Another way to get the center of mass inside this triangle is to spread the tripod legs less. I can't see how that is making it more stable…
My experience is spreading the legs more does help with stability, but it makes this triangle smaller, so it push the center of gravity longer outside.

[basker]

...the flexibility of smallest or lowest legs of a tripod are easily a tripod's achilles heel...
Dave Hartman

Dave,
Good to hear from you. My tripod (RRS 24L) does feel flimsier with all four sections extended. I do it sometimes to avoid crouching or shoot upwards, but I agree shorter seems better. Still pretty nice for a lightweight system. I rarely use it with a lens above 135mm. I also agree that a much longer lens would prefer a heavier tripod.

I admit that I too have an old Bogen . The center column can be rotated, so I put a monopod head on it to add tilt. Looks kind of cute with a Coolpix A on it.
Sam

[Bjørn Rørslett]

It is a common mistake to assume "heavier is better" when discussing tripods. A tripod's stability relates to its construction principles and torsional rigidity more than weight. The tripods I'm using range from 1.2 kg upwards and all of them hold a 600/4 or similar with ease (we're talking about Sachtler tripods here).

[Akira]

Another way to get the center of mass inside this triangle is to spread the tripod legs less. I can't see how that is making it more stable…
My experience is spreading the legs more does help with stability, but it makes this triangle smaller, so it push the center of gravity longer outside.

If you decompose the vector of the gravity into the vector component along the tripod leg (a) and the one perpendicular to the leg (b), (a) will be stronger while (b) will be weaker when the leg is spread less.  The vector component (b), in effect, bends the leg towards inside of the tripod.  That may be why the tripod feels more stable when the leg is spread less.

On the other hand, the stability against the torsional force can be weaker when the legs are spread less.  So, the best total balance of the stability may change according to the shooting situations.

[basker]

It is a common mistake to assume "heavier is better" when discussing tripods. A tripod's stability relates to its construction principles and torsional rigidity more than weight. The tripods I'm using range from 1.2 kg upwards and all of them hold a 600/4 or similar with ease (we're talking about Sachtler tripods here).

Bjørn,
Seeing pictures of your tripod is how I got the idea that hinge width is a big deal, especially in torsion. My tripod, including the ballhead and clamp, is about 2 kg and fits my 70 inch eye height. If I did, miraculously, get a 600/4, there would be an equally miraculous fluid head Sachtler attached to it. No disparagement was intended when I assumed that setup would be heavier. I misspoke, I should have said "heavy duty" to be accurate, and I do love hearing from you.
Best wishes for your new home,
Sam

[Seapy]

Think this is a fairly steady position to support the camera. 

I used it with a radio remote to shoot behind goal action while I was on the sideline.  The flash was so I knew it was actually making exposures.

Inverting the image in pp of course. 

[basker]

Think this is a fairly steady position to support the camera. 

A poster for "Inside the Apex!" Love it when I see something and just know it works.

Looks like it walked there during "War of the Worlds." 

Thank you,
Sam

[Seapy]

 

Well I wanted the camera low for drama and in case a ball (or player), hit the tripod I wanted protection for the D1, which back then was still precious and the 18-35 lens, which still is.

[David H. Hartman]

My Tiltall can resonate for up to 45 seconds after the mirror comes up. I would guess this was an F2 but I don't remember. This is not an endearing feature.

[Les Olson]

A tripod's stability relates to its construction principles and torsional rigidity more than weight.

Perhaps stability is being used to mean different things here.  Stability meaning resistance to being pushed over, as by a wind, is related to weight and to the geometry.  Torsional rigidity has nothing to do with stability meaning resistance to being pushed over, within the range of forces a photographer is likely to encounter. 

Torsional rigidity and vibration damping also relate to weight, because both depend on the elastic modulus of the material and the mass of material.  For practical purposes, any desired level of rigidity can be achieved with any material if you use enough of it.  Where design comes in is (1) the diameter of the legs, assuming they are hollow, because larger diameter means more rigidity for the same weight, and (2) in the joints between leg sections, because the joints are always much weaker in bending than in compression, so their ability to support a weight along the axis of the legs is excellent, their ability to resist a force applied to one side may be poor.

[Bjørn Rørslett]

'Stability' as in the sense of being able to hold a camera/lens stable over time. Torsional rigidity means less proneness to being twisted during the exposure.

The "crutches" construction makes say a Sachtler quite light in weight compared to traditional tripods, yet it provides a very stable support. I have used these tripods for decades so am pretty familiar with their behaviour in the field. They also have the additional feature of working well immersed in mud, snow, or water.