|
What's So Special About Carbon Fiber?
As long as we're on the subject of tripods, it's time we looked at the materials they're made from. The hype is that really good tripod legs are made from carbon fiber. But what's so special about carbon fiber?
Anyone who's ever lusted after a carbon fiber tripod knows that they are lighter weight than comparable aluminum models. A chunk of aluminum is heavier than a piece of carbon fiber the same size because aluminum is denser. Aluminum has a density of about 2.7 grams per cubic centimeter while that of carbon fiber is only about 1.6 grams per cubic centimeter. But if you compare the weight of a carbon fiber tripod to an equivalent aluminum one, you'll find that you'll save somewhat less that what is implied by this difference in density. The reason comes at least in part from the fact that carbon fiber tripods aren't made completely out of carbon fiber. The leg tubes may be, but neither the fitting that join the legs into a tripod nor the leg locks that stop the nested leg segments from collapsing back inside each other are. The use of carbon fiber can only save weight on that portion of the tripod actually made from carbon fiber.
In terms of actual weight savings, it is reasonable to assume you can save about a pound or two by going with carbon fiber. It's hard to say exactly how much since the models Gitzo and others make don't compare directly when switching leg materials. That's certainly not an insignificant weight savings, but it comes to only a fraction of what you carry around when you add in the weight of your camera, lenses, camera bag and everything else. Still, every little bit helps, and I'm certainly not suggesting the savings don't matter. They do.
But it depends on how much it's worth to you to save that weight. Those one to two pounds are going to cost you a hundred dollars or more apiece to shave off. You need to decide whether spending that on going with carbon fiber would money well spent or whether putting it to a better lens would be a better idea. If money were no object, all of us would buy lots of stuff we probably can't afford or justify in the real world.
Now let's consider the impact of carbon fiber on image sharpness since, after all, that's the main purpose of having a tripod in the first place. Officially, carbon fiber is more rigid than aluminum alloys. That's just a scientific fact. A tripod leg made from either material is essentially a hollow pipe. Anyone who has ever struck a metal pipe with a hammer knows that it will ring with an almost musical tone. That's the vibration travelling up and down through the metal of the pipe. All metals just do that. There's a reason they make bells and gongs from metal. Carbon fiber doesn't do that. If you strike it, it will go "thud," but the sound won't persist. The vibration doesn't travel through the material very well, so whatever may have been initially imparted to the material dies out quickly.
Metal is also much more malleable than carbon fiber is. Thin pieces of metal can bend and flex. The only way to make metal rigid is to make it thick. Carbon fiber materials though are inherently stiffer even when thin. Make them too thin and they can break in two, but the stuff really won't bend much. The carbon fiber in the newest Gitzo tripod leg tubes is a mere 1.3mm thick. Make an aluminum tube this thin and I bet you could bend it with your hands. Although even thinner, think of crushing a Coke can to get an idea. You can make carbon fiber thinner than aluminum and still achieve the same rigidity.
If you make it out of enough metal, it is certainly possible to make an aluminum tripod just as rigid as a carbon fiber one is. There's little that can be done though about the difference in vibration damping. But in real world use, it this may or may not make a difference in your images. At fast enough shutter speeds, you won't notice any difference. At long enough exposures you probably won't either since any vibration caused by pressing the shutter release button or the mirror flipping up out of the way will be negligible over the total duration the shutter is open. But between these two extremes is where many nature images get shot and it is possible your tripod leg material could make a difference provided you have done everything else right. It's up to you to come to terms with how much of a perfectionist you are, and again, how much that added vibration damping is worth to you.
And all this leads me to the carbon fiber advantage I rarely see others talking about. When I started out in photography years ago, I bought an aluminum Gitzo tripod. After they started coming out with carbon fiber models, I switched. Perhaps the single biggest change I noticed back then had to do with temperature. Carbon fiber simply doesn't feel cold during winter the way an aluminum tripod does. Anyone who's ever touched an aluminum tripod on a winter morning in the snow before sunrise knows the problem. Aluminum tripods can quickly bleed the warmth right out of you in the cold. Touch a carbon fiber one though and the same thing doesn't happen. Personally, I'd pay extra for carbon fiber based solely on this difference.
All things being equal, a heavier tripod will naturally be more stable since it would take more force to move it. But all things are not equal when comparing different materials for tripod construction. Carbon fiber is inherently more rigid, pound for pound, than aluminum is. It also doesn't transmit vibration as readily. But carbon fiber is significantly more expensive than aluminum, and you need to decide it it's worth it for your budget and needs. But the single most impressive difference to me is how the two handle in cold weather.
I love using a carbon fiber tripod, especially this time of year. I just make sure I remember to grab it by the carbon fiber legs themselves and not by any of the aluminum parts joining those leg segments together. The aluminum still gets just as cold as ever.
| 
