Archived posting to the Leica Users Group, 2004/11/03
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]That's an interesting number. If I did the math right, it works out to about 0.025 degrees. So why is it so hard to level the camera with a wide-angle lens? I suspect the answer is in the "minification" and restricted field of view of the usual finders. Visual size reduction plus shorter baseline equals greater error. The finder brightlines, if it even has them, might easily be off by a degree, too. Without brightlines, leveling is probably hopeless since your eye has no reference as to what is square. Accurate reference lines in the finder are the only answer, as was mentioned earlier this morning, but the the lines must be confirmed square to the camera film gate, too. Photoshop is easier. How did we ever live without it? >I had an interesting discussion with a cabinet maker and later with an >Intensive Care physician several years ago about the ability of our >"uncalibrated eyeballs" to discern "out-of-true" lines. Cabinet makers, >I learned, have always known that the unaided human eye (assuming >average eyesight), can detect 1/64" and 1/128" over a length of 3'. The >physician was treating my wife, who had a Swan-Ganz (sp?) catheter. For >the treatment to work properly, as I recall, a long level had to >extended horizontally from the catheter entry site in her chest out to >the side of the patient. Several nurses were fussing with the thing >when the doc came in and, rather impatiently explained to the nurses >that the human eye was more capable of detecting out-of-level conditions >than by using the level. He then proceeded to demonstrate, and he was >right! > >Amazing what the eye can do! > >Ken Frazier > >_______________________________________________ >Leica Users Group. >See http://leica-users.org/mailman/listinfo/lug for more information -- Regards, Dick Boston MA