I have a RRS PCL-1 panning clamp, an acratech level head and recently bought several sunwayfoto plates and rails.
I normally level the acratech level head, then I mount PCL-1 panning and the rail on top of the acratech level head, and my guess is that the rail should also be levelled (as they just sit on top of each other), but is not, there is a small error.
But, if I turn the PCL-1 panning clamp, the error in the bubble of the sunwayfoto gets worse.
the bubble level of the PCL-1 is ok in terms of matching the acratech level head.
so, my guess is that the sunwayfoto bubble level is failing, but I bought a few different Sunwayfoto rails and heads and they all seem wrong at some degree.
Do you have any experience having wrong bubble levels in general? or is just sunwayfoto bubble levels are not very accurate?
thanks
Factors for bubble levels can vary by just how they are mounted in the rail or the rail could have a twist or bend or temperature influenced. The bubble should be fine as a bubble is working with gravity. Old days surveying would just level and turn 180 degrees and see how much is off, then split the difference. There are multiple errors going on. It is like the old saying, how do you tune two piccolos..shoot one of them. Pick one that seems right and go with that one.
Patrick
Any given bubble level can be installed wrong and not produce results that are actually level. The classic way to check any level of any type is to find a surface like a counter top or table or desk that shows level, and then rotate the level to four different orientations, and see if they all indicate level. An improperly set level will fail this test, and a correctly built or adjusted level will pass this test. You can get an idea of how bad the level is by how much it changes as you rotate it. Note that this method will not work for some installed levels if there is no flat reference surface on the bottom. An example is a tripod that has a level in it.
I sent my MPR-CL II back to RRS as the bubble level was off. They compared it to their others and told me that they were all off to some degree and that it was within their spec, or something like that. My bubble levels don't match up when I use the flash socket double bubble, rail bubble, and leveling base bubble. I usually defer to the flash socket double bubble thinking that it may be closest to the orientation of the camera sensor. Anyway, that usually works out fairly well with my panoramas, though not perfectly perfect.
You could test by setting a level that you know is accurate on top of the sunway plate.
If you have a camera with a built in level display that's also a handy reference point.
I use a bull's eye level on my DIY pano rig and adjust my setup until it shows level throughout a full 360 degree rotation. It was kind of a pain to learn to do at first but now I can make the needed moves pretty quickly.
