Not sure the rule would be your limiting factor, but I've used rubber bands to put a longer steel ruler onto the LensCal rule in cases where I wanted to determine in a single pass just where the "zone" was...
C. D. Tobie
C. D. Tobie
Global Product Technology Mngr.
Digital Imaging & Home Theater
I need to buy one of these devices. I certainly like the price and simplicity of the SpyderLensCal over the LensAlign. The lens that I need to calibrate most is a Nikon 80-400VR with my new D700. Calibrating @ 400 @ 25 to 50 times fl would be in the 33 to 65 ft range. That, coupled with a f/5.6 max aperture, makes me wonder if depth-of-field would render SpyderLensCal useless under these conditions. LensAlign sells a long ruler kit for this situation. Would I be able to use the standard ruler of the SpyderLensCal satisfactorily for this lens?