Center columns are often described as some sort of evil spirit. The usual party line says "never use a center column and if you have one, never raise it". That's an easy solution if you are shooting landscapes, where critical positioning of height may not be important. What if it is? Will your image totally fall apart if you raise the center column an inch or two?
Here we investigate *intelligent* use of a center column. I chose two configurations for my now older Gitzo 2 series 4 section G1228 (all 4 leg sections fully extended) and D200. First, using a 70-200VR at 200mm, then adding a TC14. My center column has a maximum extension of about 9 inches. The images were shot with the center column down (fully retracted), at about 2", 4.5" and fully extended at 9". As with all my test images, these are 100% crops of the original out of camera JPGs, shot with in camera HIGH sharpening.
Without the TC, at 200mm, I generally find that this lens is at the edge of the envelope of what this leg set can handle when shot using a remote without any mirror up delay. Although I did not shoot any mirror up images in this test series, I have always found that simple remote shots are virtually indistinguishable from mirror up images at 100% zoom or less. Any differences are truly pixel peeping.
Adding the TC14 is another story. I always see some image degradation when using a remote without mirror up.
The 200mm shots without the TC might lead you to believe that the world will not end if you raise your center column, especially if it is only a few inches. Arguably there is little or no difference. A real world shot of very fine detail might show some degradation, on the other hand you might have missed the shot entirely if you spent a minute or two trying to adjust your tripod height to get the required framing.
With the TC14, things are a little different. Here there is obvious degradation that increases with increasing height of the center column. Consider, of course, that this configuration was chosen to represent a slightly overloaded payload.
Had I used mirror up things would have certainly improved. Other tests indicate that with mirror up the images would be essentially identical in all cases. Mirror up can overcome a lot of evils. With long lens technique, the results would be based on each shooters skill and daring so my results would not reflect your results, which might be better or worse. Consistency would suffer too.
Consider also that macro shooting, even with shorter focal length lenses such as 60, 90 and 105mm, may suffer more degredation than that experienced with this longer focal length telephoto lens. Do your own tests with your own gear the way you really shoot.
The important point here is that a center column, intelligently used, with good choice of shooting technique, may in some cases be a lesser evil than fighting with tripod leg extensions to achieve precise framing, possibly missing important opportunities. I cannot stress enough that the purpose of this image is not to "bless" center columns. I only want to encourage people to test their own gear, in their real world shooting situations, and come to their own conclusions. One test is worth a thousand internet forum opinions.