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Dave and EBH thanks For responding and making good points. I will try a stepwise sequence. Let's assume as Dave noted that I will use the ball head to pan.
Let me respond to leveling first. I have used the level on the tripod legs to level the tripod legs. It seems to work but takes time even on a flat surface. In the field it maybe more difficult. I thought adding an additional way to level would make it easier. So if the concern at this time is simply to level the base on which the ball head that is...Show more →
If you have successfully leveled the legs, you are done leveling. The panning of the ball head will rotate on a level plane. If you aren't confident that you can level the legs, the use a leveling base below the ball head, between the ballhead and the legs.
So, next comes the nodal rail. I clamp the rail on the ball head. The two versions from RRS MPR CLII (or MPR CL) or MPR 192 both have bubble levels so I check the level again and use the ball head to re-level if needed.
Why? By doing that you are defeating what you have done by leveling below the ball head. Having done the leveling below the rotator (which is what you want) you can now use the ball head to frame your shot in the vertical axis; that is, determine what is included in the vertical dimension of your picture. You will determine what is in the horizontal direction by panning and taking multiple shots to be combined later. There is not need for the camera itself, or the nodal rails to be level, and in fact that is undesirable because it would put the horizon smack in the middle of the frame. Use the legs or leveling base below the rotator to accomplish all leveling, then use the adjustment of the ball head to frame you pano aesthetically. (However, see below for the effect on NPP alignment.)
Next I clamp the L plate with the 5d with L bracket on to the nodal clamp. I adjust the clamp for nodal point and rotate the ball head to shoot the images.
That's fine. However, one of the limitations of using just a single nodal rail is that when you pitch the camera up or down using the ball, you move the NPP of the lens (which is located above the ball) forward or backward of the axis of rotation. In other words, the nominal location of the lens NPP over the axis of rotation that you achieved by adjusting the camera position on the nodal rail is defeated. You could always shoot with the nodal rail level, as you discussed above, but they you will be limited to having the horizon in the center -- boring! Instead, you can adjust the camera further front or back on the rail to compensate for the effect of the pitch and return the NPP of the lens to being above the axis of rotation. You could do this precisely with trigonometry, but for most panos if is sufficient to just eyeball it. Before pitching, note what part of the lens is directly over the axis of rotation, then use the ball head to pitch the camera up or down, and then adjust the camera on the nodal slide to return the noted part of the lens to the rotation axis. If you pitch forward, yo will move the camera back on the slide; if you pitch back, you will move the camera forward.
So, I eliminated the need for another way to pan.
Huh? You only need one way to pan horizontally, and that's done by the panning of the ball head. If you want to do multi-row panos, then you will need a vertical arm and a means of rotating around the other axis, and that also solves the problem of moving the NPP when you pitch. But to keep it simple, let's not get into that right now!
So, if this is correct, I am uncertain which nodal is correct. I am shooting with a 5d MII. My wife has a 7D. Available lens are 17-40, 24-70, and 70-200. Each rail from RRS is of a different length or work differently whether collared or non-collared lens are used. I understand beyond certain focal points parallax is not a problem, If I try to be most flexible for different lens than the 192 seems to be good but it may rarely used when parallax is a issue. If, so than one of the other two nodal would work, MPR CLII...Show more →
The best way to determine the NPP for your lens (and how that translates to a rail setting for you practical camera and rail system) is empirically, by setting up a scene with something close against a background with recognizable feature. (I stick a long garden stake with a nail sticking out the top in the ground, with a brick wall as a background.) Then take pairs of pictures with your setup, rotating so that the foreground object is on the left side of one picture, and the right side of the other. Adjust the camera position on the nodal rail incrementally until the position of the foreground object against the background does not change between the pairs.
There are also databases of lens NPPs on the internet -- here's one: http://wiki.panotools.org/Entrance_Pupil_Database. You will need to take the measurements in the database and translate them to your camera and rail combination.
I now this seems complicated, and indeed there is some up-front work to get set up to make panoramas. But one you are past that, it gets much easier and automatic, and you'll enjoy working in a new form of photographic expression. Have fun!