In designing the PD Travel Tripod, our goal was to create an ultra-portable tripod that still offers pro-level performance. Obviously "pro-level" is a subjective term, but in a nutshell it means:
- It can safely hold oft-used professional camera gear - like a full-frame DSLR and a 70-200 lens
- It lets you take sharp, high-quality photos with that gear
- It can deploy to eye-level for most people
- It can do these things as well as (if not better than) much larger travel tripods on the market that are frequently used by professional photographers
Some of these standards are subjective, too. Camera/lens combinations vary endlessly in terms of size, weight, and distribution of mass. How sharp your photos are depends on factors like focal length, wind, the type of ground you're on. But one thing that can be done in a very exact and scientific manner is to measure how different tripods perform in relationship to each other.
This article explains how we used a rigorous scientific approach to testing the overall performance (primarily stability and weight capacity) of the PD Travel Tripod as it relates to other high-quality travel tripods on the market. This testing was a critical part of our product development, and serves as physical evidence backing up all the glorious claims our marketing team has made about this product.
If you really wanna go deep on performance, read the definitive PD Travel Tripod review on TheCenterColumn.com.
Which brings us to our next point...
MEET DAVID BERRYRIESER OF THECENTERCOLUMN.COM
In the most serendipitous of circumstances, a person who is arguably the world's foremost expert in tripod stability testing lives in our own backyard. Meet David Berryrieser, Stanford Physicist and founder of TheCenterColumn.com.
The Center Column was born out of David's quest to find the best tripod. He realized that despite endless tripod reviews, comparisons, and online forum debates, there really was no clear, consistent methodology for measuring tripod stability. Hence, he used his physics background, garage, and free time to invent one.
READ DAVID'S REVIEW FIRST
As mentioned before, David's review of the PD Travel Tripod is the most complete one we've seen with respect to stability and performance testing. The rest of this article reference's David's data quite a bit.
STABILITY VS. COMPACTNESS: A NATURAL TRADEOFF
You don't have to be a physicist to understand the idea that bigger, heavier tripods tend to be more stable than smaller, lighter ones. In some contexts—like studio photography—tripod size and weight is not important. But when it comes to travel tripods, it is of the essence. Hence, when you compare travel tripod stability, you should also compare travel tripod size and weight.
David does through his Volume-Weighted (VW) Scoring System. Here's another one of his articles explaining it. The charts below are based off of David's data.
Scroll down to learn more about how David performs his stability testing. But first, we'll start with the results of his testing.
IN VOLUME-WEIGHTED STIFFNESS, THE PD TRAVEL TRIPOD IS AMONG THE BEST
Here's how the PD tripod (Carbon and Aluminum) stacks up to other travel tripods he's tested.
Blue = PD Travel Tripods
Red = 3 very popular travel tripod models that we did a lot of benchmarking against. That's not to say you should only compare our tripod to these ones. These are just 3 models with high sales volumes that are broadly recommended by our retailers, other photographers, and Youtube reviewers. They also are similar to the PD Travel Tripod in terms of number of leg sections, packed size, and deployed height.
As you can see, the PD Travel Tripod does very well against it's competitors in terms of volume-weighted stability (VW Score). A few things to note:
- Scroll down to learn more about how exactly VW Score is calculated
- This list shows the top 20 tripods out of 26 on the full list
- The LeoFoto tripods on this list lack a center column. This means their deployed height is shorter and their packed length is considerably longer than the PD Travel Tripod.
- The prices for the Gitzo, RRS, and LeoFoto tripods on this list do not include ball heads, which can easily add another $100-$400. The PD Travel Tripod price includes a ball head.
- The "PD Aluminum" tripod listed is a pre-production model. The production model has slightly different specs, and the same height/volume as the PD Travel Tripod Carbon.
IN OUTRIGHT STIFFNESS, THE PD TRAVEL TRIPOD IS COMPARABLE TO OTHER HIGH-QUALITY TRAVEL TRIPODS
Here's that same list, ranked in order of outright stiffness:
Some more important notes:
- Again, this is 1-20 of 26 travel tripods tested. The PD tripods are both in the middle of the pack.
- Stiffness rating is calculated without tripod heads, since many of the more expensive tripods on the list don't come with heads. The PD Compact Ball Head (which comes with our Travel Tripods) performs very well compared to other more standard shaped ball heads, and therefore in practice the PD Travel Tripod's overall stiffness is a bit higher than this chart indicates relative to the competitive field.
Indeed, the PD Travel Tripod is not the outright stiffest of the bunch. But it is most certainly comparable. Keep in mind that the stiffness measurement is meaningless without context. Every single one of the tripods on this list can hold a full frame DSLR with a 70-200 lens and take sharp photos in most conditions. According to David, any tripod with a stiffness number greater than about 300 should do the job well. What's the difference between a 400 and a 500 and a 600? A higher number means the tripod will let you get sharper shots in more situations with heavier gear.
IN PURE PORTABILITY, THE PD TRIPOD IS THE BEST IN ITS CATEGORY
Here's that same list, ranked in order of packed volume:
- Note, once again, the PD Aluminum tripod listed here is pre-production. The production model has the same specs as carbon fiber model, which would put it at the top of this list.
IN DEPLOYED HEIGHT, THE PD TRAVEL TRIPOD IS AMONG THE BEST IN ITS CATEGORY
Here's the list ranked in order of deployed height:
- Again, the final PD Aluminum production model has the same specs as the carbon, which is #5 on the list.
Height is traditionally one of the main tradeoffs when buying a travel tripod, and our unique architecture helped us beat the curve. We believe that having a tripod which can deploy to eye-level is rarely an absolute must-have, but it's frequently an important aspect of usability. Hunching over quickly becomes a chore.
THE PD TRAVEL TRIPOD IS PRICEY, BUT FAR FROM PRICIEST
Finally, here's the list ordered by price. Important to once again note that the models listed above the PD Travel Tripod do not include a ball head, which can easily run $100-$400.
At $350 for aluminum and $600 for carbon fiber, the PD Travel Tripod is not among the cheapest travel tripods on the market. We wrote a long Field Note about why our tripod costs what it does. If you're curious about it, we recommend having a read.
In short, the PD Travel Tripod took 4 years to develop. Its unique architecture is comprised of 336 distinct parts. Many of these parts require quality assurance testing well beyond what is needed for traditional tripod designs. We work hard to ensure fair pay and safe conditions for our factory workers. Our tripods (and all products we make) are 100% carbon neutral and they are also guaranteed for life.
You can absolutely get a pro-quality travel tripod for less. But we stake our reputation on the value that exists behind our products' price tags.
REMEMBER, IT'S ALL RELATIVE!
We can't stress this enough...the scores above are not absolute. Every tripod on that list will hold your D5 + 70-200 and give you perfectly sharp images in many conditions. While no tripod on that list will give you perfectly sharp images with all gear in all conditions, a higher scoring tripod will give you sharp images in a greater range of conditions and/or in a more portable package.
WEIGHT RATINGS ARE NOT VERY USEFUL
The question of a tripod's "weight capacity" or "weight rating" has no simple answer. While the Peak Design Travel Tripod has an advertised weight capacity of 20 lbs, you can actually put over 80 lbs of gear on top of it without the center column slipping. But your image will be less sharp, especially when you're shooting at a 400mm focal length, and the wind is gusting at 40mph.
The “weight capacity” stat that many tripod manufacturers (us included) publish is pretty much meaningless. There's zero standard for how to measure it, and most manufacturers don't even explain how they arrived at the number they advertise. Here are David's thoughts on that.
In essence, "weight capacity" is a measure of how stiff/stable a tripod is. The problem is that tripod stiffness is not easy to convey in a single, digestible number.
That's why we love what David is doing at The Center Column. He's creating an empirical methodology for testing tripod stability. He takes those results and then provides an analysis that considers all the different contexts and use cases a tripod may be subject to. The result is a holistic view of what a tripod does well (or poorly) compared to other similar tripods.
Let's talk about this testing methodology.
STABILITY = STIFFNESS AND DAMPING
A tripod's ability to hold your camera perfectly still can be measured in 2 ways: stiffness and damping.
Stiffness: A Tripod's ability to resist movement caused by external force.
It's what holds the camera still in spite of forces like gravity and wind working against it.
Damping: A Tripod's ability to return to stillness once moved.
No tripod can hold all cameras still in all conditions. When you touch your camera or bump the tripod or a big gust of wind comes along, your camera will move. That momentary movement creates vibration, and damping measures how quickly a tripod stops that vibration.
TESTING STIFFNESS AND DAMPING
So, how do you consistently measure tripod stability across many different makes and models? If you guessed harnessing the simple physics of harmonic oscillators, you're absolutely right!
Let's break that down:
- A large weight (both heavy and physically large, with high angular inertia) is placed atop the tripod.
- The weight is bumped, causing it to rapidly move back and forth (oscillate).
- The speed (frequency) of oscillation is measured, which lets you calculate stiffness.
- The time it takes for oscillations to stop (rate of decay) is measured, which lets you calculate damping.
- The weight is bumped vertically to measure pitch stiffness/damping.
- The weight is bumped horizontally to measure yaw stiffness/damping.
- Each test is conducted multiple times and the results are averaged.
Here's what that test looks like for a prototype of the PD Travel Tripod:
And for a 3rd party tripod made by MeFoto:
In this comparison, you can see with your bare eyes that the prototype PD Travel Tripod (top) horizontally vibrates significantly faster than the MeFoto (bottom), meaning it has more stiffness. The PD Travel Tripod also stops moving significantly faster than the MeFoto, meaning it has better damping. Thus, the PD Travel Tripod prototype has better overall stiffness. For the specs on the production PD Travel Tripod, scroll up to the top.
THE BERRYRIESER EQUATION FOR VOLUME-ADJUSTED STABILITY
The next step involves sabermetrics, the use of a bunch of different data points to generate a simple, easy-to-compare stability score.
Here's the formula to calculate that score:
Stiffness is measured in 2 ways: pitch stiffness (PitchStiff) and yaw stiffness (YawStiff).*
Pitch stiffness measures vertical stiffness (resisting an up-and-down motion) and yaw stiffness measures horizontal stiffness (resisting a side-to-side motion. Taking the harmonic mean of pitch and yaw stiffness is an average biased toward the weakest of the two measurements. A tripod is only as good as its weakest link.
Stiffness is calculated in newton meters per radian, which is the amount of angular force (torque) required to twist the tripod by one radian (which is about 57 degrees). The actual measurements are done at a much smaller scale (like milliradians, or 1/1000th of a radian) but multiplied up to make them easier to compare.
Each tripod is tested 6 times, thrice for pitch stiffness/damping, and thrice for yaw stiffness/damping. A tester records data using a Raspberry Pi computer with an accelerometer, which automatically collects and plots the data as soon as the tripod stops moving. The numbers from the 3 tests are averaged, and then input into the calculation above, yielding a stiffness harmonic mean.
The stiffness mean is then normalized by tripod height and weight. This is what turns the stability score in to a Volume-Adjusted Stability Score (VA Score on the above charts). As mentioned earlier, deployed height and weight are inextricably tied to stability. They're also tied to the usefulness of a tripod. Hence, height and weight are added to the equation. Height is a multiplier, which slightly penalizes shorter tripods. Weight is a denominator, which slightly penalizes heavier tripods.
*Notably absent from this score is damping, which the PD Travel Tripod happens to score very highly on. While damping is a factor in stability performance, and something that we at PD tested for heavily, David considers damping to be less integral to stability than stiffness. Here are his thoughts on it.
If you've read all the way to the bottom of this article and still want to know more, that means one of two things: you are either David Berryrieser himself, or you absolutely flip your lid when you visit TheCenterColumn.com. Go, now, and enjoy.