Archived posting to the Leica Users Group, 2000/08/29
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]In a message dated 8/29/00 11:21:58 AM Eastern Daylight Time, jim_brick@agilent.com writes: << DOF preview is intended for just that. Checking DOF and making sure what you want in focus IS in focus and what you want out of focus IS out of focus. It works. I've been using it on 35mm SLR's and view cameras since 1959 and on Hasselblads since 1962. This is how these cameras work. What can I say. The professional photographic industry is based on this fact and principal. Used properly, WYSIWYG. Exactly. Jim >> First, any damn fool knows that the lens has to be stopped down. Second, the whole matter of depth of field is itself an approximation based upon an arbitrary, mathematically derived standard - the so-called circle of confusion, which relates only to relative "acceptable" sharpness, not a precise determination of greatest possible definition or resolution or even finest resolution within a given frame, let alone as compared to areas considered out of focus. Third, you don't even bother to address the issue of how to determine the rendering of out of focus areas on the film by looking at a groundglass, with the lens either stopped down to shooting aperture or wide open. Fourth, the newer the camera or focusing screen, as the case may be, the brighter the screen is likely to be and less likely to be capable of rendering clear distinctions between areas in focus and out of focus, IME, let alone giving even an approximate idea of what out of focus areas will look like on the frame. Fifth, we were speaking of 35mm photography, using lenses of focal lengths most commonly used with RF cameras. In that context, even a lens of a focal length of 80mm, like the Hasselblad "standard" lens, will be more likely to show differences between areas in and out of focus than the 35-50mm range under discussion. Sixth, in the context of the thread, I was responding to the contention that RF cameras were not useful in situations where the rendering of out of focus ares was a consideration. I disagree with that assertion. Joe Sobel