Manfrotto Ball Head

[Stagecoach]

Although it won't adress the problem of "sag" mentioned previously, many people suggest hanging something below the tripod to increase its stability. Should one take that additional weight into consideration when a manufacturer's weight capacity recommendation is a criterion for purchase?

I would certainly think so. That hanging weight is causing additional loading on the legs and joints in the same way as if a heavier camera or heavier head was being used.

[DanK]

Manfred,

Thanks for the additional explanation. However, I still think that IN PRACTICE, most of the sag does not come from the internals of the ball head. You've given a clear explanation of why, all other things equal, a larger ball should move less after fastening than a smaller ball will, but I still think it is the case that the movement of a smaller ball (at least, some smaller balls) isn't the main source of the sag.

With only one person and two hands, I had no way to mark the position of the ball in the housing while aiming the camera. However, the sag should be symmetrical: whatever moves when weight is applied to the system ought to move in reverse when the weight is removed. So, I tried this. I installed my cheaper ball head, an Induro BHD0, which has a 36mm ball. As before, I deliberately installed the camera and lens out of balance, to maximize sag. The resulting sag was similar to what I got yesterday using my higher-quality but similarly small (38mm) Markins Q3i.

I then marked the position of the ball with a piece of painter's tape (because it leaves no residue if removed reasonably quickly) and used my hand to rotate the camera back up, looking to see what moved.

This isn't a very precise way to do things, and some of the motions are small, but it seemed clear anyway. There appeared to be a very slight movement of the ball within its housing. However, there was a larger movement of the housing itself, reflecting deformation where the head attaches to the tripod.

Of course, this is only one combination of head and legs, but at least in this case, it seems that the larger source of sag is the last factor you mentioned: distortion where the head is attached. The ball itself appears to contribute less.

I'd be curious to replicate this with other equipment, but I have only one pair of legs and two ball heads.

To go back to the OP's question: I have a hunch that buying a more expensive head won't reduce her problem all that much, at least if she keeps using the same tripod legs.

Re geared heads: my point is that when using a geared head, there is no transfer of weight from your hand to the head. Whatever distortions are going to be present at the end of the adjustment, wherever they arise in the system, are present at the beginning. Lash is a different issue and isn't usually a problem. The weight is resting on the top surface of a gear or screw (I've not disassembled one) both before and after the adjustment, so the slop between the top of one surface and the bottom of the one above it doesn't come into play.

Dan - some of this is basic mechanics, but let's start at the beginning. If the camera /lens combination is perfectly balanced on the tripod, then nothing else is needed as the whole assembly would just sit there in equilibrium. Unfortunately, this is virtually never the case, so the camera with a lens sticking out front applies a downward force some distance along the moment arm. This force (measured in N-m or ft - lbs) has to be resisted, hence the ball head (or other type of head) on the tripod. It applies a resistance equal to the force that is trying to rotate the camera / lens assembly.

Our camera / lens assemblies are not perfectly balanced so we do need to apply some level of force to overcome the torque put on the tripod head from our unbalanced setup.

This is where are larger diameter ball head has an advantage over a smaller one because both the force applied and the distance from the centre line of the ball come into play. Because a 2" / 50mm ball head has twice the radius of a 1" / 25mm ball head, we only need half the force to overcome the same amount of torque on the larger ball head than the smaller one. The larger ball head has a far greater surface area for the clamping, so the force per unit area will be smaller, resulting less deformation and wear and tear on the ball head mechanism. Bigger is better, but heavier and more expensive to manufacture.

Geared heads are a bit of a different beast and gear lash is related to "play" in the system. This is primarily due to the tolerances between the two gears that engage. Tighter tolerances (which is generally related to precision in the design and manufacture of the gear train) and its components (small diameter axles can exacerbate this issue).

When it comes to the smoothness of a ball head, this is related to design and manufacturing (materials and tolerances). Ball heads have three main parts; the ball, the cup it sits in and the liner (or bushing) that separates the ball from the cup. The liner is responsible for the smooth operation and when pressure is applied to it, it elastically deforms during the clamping process. This elastic deformation (i.e. it returns to its former state when clamping pressure is removed) is where a large part of the sag comes from. The friction from the clamping action is what holds the camera and lens assembly steady. Other issues in the construction of the tripod and head can also contribute to the the droop. The screw that attaches the head to the tripod can be fairly small in diameter and any force on it can cause a minor amount of deformation. This can show up as sag as well.

The focusing collar on long lenses primarily serves one main purpose; it provides better balance to the camera / lens unit so less force is required to hold the lens steady.

[Manfred M]

Depends on the tripod, to some extent Dan. I have three sets of legs (five if you count my Libec video tripod and my Feisol table top tripod). The smaller ones are Benro travel tripods and the larger one is biggest, heaviest tripod Feisol makes.





Looking at the smallest and largest ball heads, you can see the difference between the size of the ball itself here...





Overall the smallest leg diameter is what determines the stability of the tripod. The minimum leg diameter on the Feisol is 30mm. This is the tripod I use in all critical shots. I can (and do) replace the centre column with a plate to hold the ball head.





I definitely get some movement on the two Benro units, but with the Feisol, the sag / droop is related to the clamping in the head only. The RRS head is rated at 50 lb / 22kg and the Feisol legs are rated at 66 lbs / 30 kg.

[Manfred M]

Although it won't adress the problem of "sag" mentioned previously, many people suggest hanging something below the tripod to increase its stability. Should one take that additional weight into consideration when a manufacturer's weight capacity recommendation is a criterion for purchase?

Yes. It is part of the load you are applying to the tripod clamps and legs.

[DanK]

Manfred,

this makes a lot of sense. I suspect that the best way for me to reduce sag would be to buy a heavier and sturdier tripod. I bought the current rig to save weight, because I often carry it for long distances, including hiking up mountains. However, I am more and more often working close enough to my car that lugging a heavier tripod wouldn't be that big a deal.

I'm sure you know, but others on this site might not, that there is tremendous variation in quality within any given size range of ball head. When I found myself dissatisfied with the Induro, I wanted a better (smoother) small ball head because of weight. I read lots of reviews, and at that time, the choice seemed to come down to two options: Markins and RRS. I forget what design detail led me to choose Markins, but I recall that it was something that pertained only to the small RRS heads, not the larger ones. The Markins is superb, with one exception: whatever lubricant they use must congeal at very low temperatures because the ball becomes very difficult to move on cold winter days.

[Manfred M]

Manfred,

this makes a lot of sense. I suspect that the best way for me to reduce sag would be to buy a heavier and sturdier tripod. I bought the current rig to save weight, because I often carry it for long distances, including hiking up mountains. However, I am more and more often working close enough to my car that lugging a heavier tripod wouldn't be that big a deal.

I'm sure you know, but others on this site might not, that there is tremendous variation in quality within any given size range of ball head. When I found myself dissatisfied with the Induro, I wanted a better (smoother) small ball head because of weight. I read lots of reviews, and at that time, the choice seemed to come down to two options: Markins and RRS. I forget what design detail led me to choose Markins, but I recall that it was something that pertained only to the small RRS heads, not the larger ones. The Markins is superb, with one exception: whatever lubricant they use must congeal at very low temperatures because the ball becomes very difficult to move on cold winter days.

I bought the Feisol / RRS combination primarily for studio use, but found that other than weight and length, the combination was so good that I travel with that combination whenever I drive somewhere (and that includes international travel via air, so long as I drive rather than use public transport on the ground).

The main reason I went RRS is that a lot of people I knew were using it and Markins was known only by reputation. The RRS head works well in really cold weather and the action is very smooth. There are a few features that I would like to see improved (a more aggressive knurl on the main knob (would be useful especially when wearing gloves) and easier to read numbers on the drag adjustment, but those are more quibbles than anything else.

If I had an unlimited budget, I would seriously consider some of the Arca-Swiss or Linhof heads.

[CatherineA]

Thank you for all the replies. They were all very helpful to me!

[rpcrowe]

Although it won't address the problem of "sag" mentioned previously, many people suggest hanging something below the tripod to increase its stability. Should one take that additional weight into consideration when a manufacturer's weight capacity recommendation is a criterion for purchase?

IMO, I would calculate this in relation to the capacity of the tripod legs but, not necessarily when calculating the capacity of the tripod head.

Additionally, another factor that influences the rigidity of the tripod legs is the number of sections that the leg is comprised of. Fewer sections for the same height and with the same diameter tube are usually more rigid than a tripod with more sections. In other words, given the same tube material and diameter with the same length; a tripod with three leg sections is usually more rigid than an equivalent tripod using three or four sections in each leg.

However, this does not influence the sag that Catherine referred to in the original posting...

[Rufus]

...I would ..[take account of the additional stabilising weight]...in relation to the capacity of the tripod legs but, not necessarily when calculating the capacity of the tripod head...

That is a distinction I shall bear in mind for future reference.

[Manfred M]

Fewer sections for the same height and with the same diameter tube are usually more rigid than a tripod with more sections. In other words, given the same tube material and diameter with the same length; a tripod with three leg sections is usually more rigid than an equivalent tripod using three or four sections in each leg.

A bit of clarification, Richard.

The stiffness of a tripod leg is largely related to both the diameter and the length of the leg (assuming the same material). Because tripod legs slide inside each other, the legs get smaller so that they can nest. This is the reason additional segments result in a less stable platform. Smaller, thinner legs are less rigid than larger diameter ones at the same length. This is the outcome of having more segments, rather than the cause.

If you have two different tripods with the same number of leg segments that extend to the same height, the one with the largest diameter outside legs will be more rigid than the one with smaller legs.

However, this does not influence the sag that Catherine referred to in the original posting...

This is not quite the case and in fact loading of the tripod will result in cause deflection in the legs. The loading is asymmetric (the camera and lens loading is not the same on all legs), so the deflection will vary based on the camera / lens position. Rotate the camera and load and deflection will change. This will be more apparent on a smaller, more flexible tripod than with a larger more rigid one. This can impact the sag of the camera / lens.

[loosecanon]

I have found that the ball heads that I have work better (clamp tighter, move when needed better, and less post clamping movement) if stored not tightened up. We tend to only unclamp heads when in use, so often remain fully tightened for days/ weeks. I also exercise my ball heads by moving a losely clamped head around all its movements, which I find makes adjustment much smoother.
May not work for you, but it does for me.

[DanK]

interesting. I'll try it. thanks

I have found that the ball heads that I have work better (clamp tighter, move when needed better, and less post clamping movement) if stored not tightened up. We tend to only unclamp heads when in use, so often remain fully tightened for days/ weeks. I also exercise my ball heads by moving a losely clamped head around all its movements, which I find makes adjustment much smoother.
May not work for you, but it does for me.

[Manfred M]

I have found that the ball heads that I have work better (clamp tighter, move when needed better, and less post clamping movement) if stored not tightened up. We tend to only unclamp heads when in use, so often remain fully tightened for days/ weeks. I also exercise my ball heads by moving a losely clamped head around all its movements, which I find makes adjustment much smoother.
May not work for you, but it does for me.

If you are seeing this with your ball head, I would suspect either a design or manufacturing issue with it.

All materials, when compressed, have two key properties. They have a zone of elastic deformation, i.e. take off the pressure and they return to their previous state; this is how springs work. Compress them and they come back to their original state.

Once the elastic limit of a material is exceeded, it gets a permanent set. Get a piece of copper wire and bend it; it will "set" in that position. This is what is referred to as "plastic distortion". It has nothing to do with plastic material, but comes from the Greek meaning of "to form".

If the tripod gets a permanent set, the way you describe it, it is due to being over tightened to the point where you have plasticly distorted the material. That means the head has been over-tightened and if the tripod is well designed this should not happen outside of a manufacturing defect with the sleeve (bushing) between the ball and the cup or some other kind of damage (contamination or excessive temperatures).

I always store my heads with a bit of compression on them so the components cannot move and get damaged in movement or in storage. I've never seem the issue you describe in any of my heads, even the least expensive ones.