Archived posting to the Leica Users Group, 2001/02/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> In response to Jim Brick, austin@darkroom.com wrote "I believe you > are 'confusing' DOF on the film with DOF on the printed image at > viewed distance. They are different. Even on the print, then again at > viewed distance have different 'DOF' too." > This theory confuses the issue even more. "DOF on the printed image at > viewed distance" - there is no such thing! Of course there is such a thing. You can make a print that has less resolution than is on the film, and thefore, it make things that aren't in critical focus on the film, be in as sharp a focus as the print can produce. It is simply a threshold issue. Anything that is above the resolution threshold of either the film, or the paper, all will be rendered the same. This is also true for the eye. > The enlargement process itself introduces an overall flattening of fine > detail when large prints are made. This flattening helps to make > the sharpest (critically in-focus) areas look more like the slightly out > of focus areas, thus giving the whole image the FALSE APPEARANCE of > greater DOF. Er, film has the same property. No matter how sharp the lense is, it can only render, on the film, as sharp as the film is. Anything sharper than the film will record is 'flattened' as you call it. This is hardly apparent, it is real. > Another example is: if you put a slight diffusing filter over your lens > when you expose a scene, the DOF isn't changed by the filter - but > visually, the scene takes on a more uniform level of sharpness > (or lack of it) and our brain THINKS there's more depth of field. Oh yes the DOF does change if the diffusing filter is diffuse enough to reduce the resolution of the lense lower than that of the film. You can only record on the film at the lowest resolution of the optics or the film, which ever is less. - -------------------------------------------------------------------- Mail2Web - Check your email from the web at http://www.mail2web.com/ .