Three Leg Sections or Four: Choosing a Tripod
If you've been shopping for a tripod, you've undoubtedly puzzled over whether to get one with three leg sections or four. Let's look at the advantages and disadvantages of each.
People are often at least initially drawn to tripods with four leg sections since they collapse down smaller for traveling. The tube for each leg segment fits inside the one above it, allowing it to extend to a reasonable height yet still easily fit collapsed in your suitcase or car trunk. Of course a three section tripod collapses the same way, but having one fewer section, it can only shrink to one third of its extended height rather than a one quarter. If it collapsed to the same size, it would be significantly shorter when fully set up.
But in order to do so, its bottom leg segment has to be skinnier than the bottom segment of an equivalent three-section tripod. Indeed, if the top leg segment of each has the same diameter, the second-to-the-bottom tube of the four-section model must be the same diameter as the bottom one of the three-section version. This stands to reason since each would be the third section down from the top, and each successive section has to fit inside the one above it.
This then means that, fully extended, a four section tripod would be inherently less stable than an equivalent height three-section one. Being smaller in diameter, the bottom leg section would be less rigid, and the extra leg joints would create more possible places for it to flex.
Speaking of leg joints by the way, you would also have more of them to adjust when raising or lowering the tripod — a lot more. A tripod with three leg sections would have two joints on each leg for a total of six joints in all. A four-section tripod would have three joints on each leg for a total of nine joints. That's a fifty percent increase over what you have to deal with when setting up a tripod with three leg sections. And more leg joints to fiddle with mean more time to set up or adjust.
In other words, all other things being equal, a four-section tripod can be better for traveling since it can collapse more, but can be a worse choice for actual use since it would be inherently less stable and require more effort to set up and adjust. Personally, I'd prefer a tripod optimized for using rather than transporting collapsed. All my tripods have always been three-section.
Some four-section tripods though do extend further than their nearest three-section tripod cousins making them more practical for tall photographers so if you need one, dealing with the extra joints may be a worthwhile trade-off. But if you do decide to get a four-section one, I'd suggest getting a model with larger diameter tubes for its top leg section so as to avoid the loss of rigidity from having skinnier bottom leg section tubes.
Update 01/22/2007 - The number of leg segments, while important, isn't the only criteria one should consider when purchasing a new tripod. One additional point worth adding for completeness is that a good quality four-section tripod is almost certainly better than a cheap three-section tripod. Consider a tripod as an investment, and get a good one. It should serve you well for a long time.