Originally posted by Lowell Goudge this just goes to prove what I have thought all along. the single plane focusing charts are all a joke.
give the camera a flat surface to focus on, and the sloping ruler away from that focus point to measure the error.
Slope is not relevant all you need to do is make small adjustments to determine what your own scale means in terms of the adjustment factor.
The only issue I see is that off the centerline focus could be different any way, since it would require the lens to be a flat field lens in order to be in focus off the centerline
LG, I am not so sure that the amount it is off the centerline is really of any significance, we are talking a degree or two is all. I also agree that the actual angle is not relevant as long as it is readily obvious in the resulting photos.
I also use the same setup to determine if replacement focusing screens accurately focus using manual lenses. It is very easy to use the micro-prism or split image to precisely focus on the box edge then determine if the manual focus is accurate.
Originally posted by VaughnA THis system makes a LOT more sense than some of the others. I'm going to try this system out soon.
I'll just have to dig out my campy box. I've got both, I'm from a mixed family, Campy,Shimano, SRAM.
My first attempt was using a SRAM Red Powerdome box, it just didn't seem right.