# Tripod Stiffness vs. Height

This series of posts addresses the problem of the stiffness of tripods versus their height, or equivalently, how much their legs have been extended.  This is critical to the work of this site as the tripod stiffness measured here is done at full height.  Tripods are measured at their maximum height because this is where they will get most of their use.  If we instead measured all tripods at some standard height, say one meter, the test data would not accurately reflect the stiffness of the tripod in use.  It wouldn’t even serve to compare tripods well, because as the data in the posts below shows, the stiffness vs height characteristics of tripods varies between models.

Modeling tripod stiffness vs height    In this post I lay out the simple mathematical models that I use to approximate to fit the stiffness vs height data.  The Manfrotto MT055XPRO3 is tested and compared to the models.  A simple power law fit with a negative exponent fits the data well, but adding a constant stiffness term fits much better and provides a much more realistic model.

Stiffness vs Height for Manfrotto MT055 Tripods   This posts looks at the other MT055 tripods available and finds that the constant stiffness term introduced in the first post is consistent across all three tripods.

Stiffness vs Height for Assorted Tripods  This post presents the same data and fits laid out in the first post, but now for a bunch of different tripods.  These results show some small differences in behavior between tripods and cast doubt interpreting the constant stiffness offset term as ‘apex stiffness’.

How do RRS ‘Long’ tripods perform at normal heights?    The similarity of the RRS models to each other presented a unique opportunity to compare the normal height tripods against their ‘long’ taller counterparts.

Approximating Stiffness vs Height   In this post, the curve fitting process was adjusted to have the fitted curve pass through the data point representing the maximum height of the tripod.  This is to best apply to our use case where we only have the stiffness at maximum height from the standard test, but want a rough approximation of the stiffness over the rest of the height range.  With only one data point, we can only fit to a model with one degree of freedom.  The resulting fits are certainly not perfect, but get us in the right ballpark.

New Score Metric   This post is the culmination of the stiffness vs height work, and lays out the reasoning and approximations used for comparing tripods to each other.  It is by no means perfectly accurate, but provides a very reasonable and useful metric that is above all else, simple and fully backed by data.

This score approach does overly penalize tall tripods, but not by much. For example, if we take a look at the TVC 34L and compute the score using the stiffness at the same height as the TVC-33, we find that the score should be 11% lower than the TVC-33 as it isn’t as stiff at the same height, and it weighs more. The score I report using the height^1.25 correction factor is 13% lower. So there is a small penalty, but it is small enough to not matter much. The rankings are simply a guide, not some definitive metric. But the rankings are correctly saying in this case that you should only buy the taller version of the tripod if you need the extra height.