Archived posting to the Leica Users Group, 2000/01/16
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Erwin Puts wrote: > > Ask any optical designer about the possibilities and intricacies of > comparing lenses, they will wring their hands in utter distress and > propose that we should eat lunch first. ... NO! You are keeping the utility of the MTF and other measurements under covers. Those of us who have had considerable experience in digital optical processing (see Science 1989;619:1181) understand the relationship between the effects on frequency encoded information and the projection of a 3D world onto a piece of film. This is a highly technical subject and beyond what we would expect of an average person or even a highly trained photographer. I would expect this to be within the understanding of an accomplished modern optical designer. To summarize: The behavior of a lens imaging ANY 3D world is exactly prediced by the behavior of the lens on a suitable two dimensional test pattern. This behavior is mathematically expressed as a set of (frequency,amplitude and phase) encodings. This information can be used by a high speed computer to demonstrate the characteristics of any lens so measured given a digitized world. This process is called a "deconvolution". I have personally used such techniques to digitally *remove* optical aberrations from Leitz photomicroscope derived images and resolve details at the sub micron level. On the other hand I would judge it impossible to completely predict the behavior of a particular lens on a given 3D world based upon the behavior of such a lens on another randomly chosen world. That is why the designers at Solms or for that matter the Midlands sit behind computer workstations and are rarely seen frolicing around the surrounding countryside snapping pictures during working hours :-) Jonathan Borden