Notes.pdf

Notes.zip

DOF Exposition.pdf

ZoneDigital.pdf

Notes

When I first came to large format photography, I found many of the explanations to be inadequate, and sometimes contradictory.  After a while, my puzzlement grew so large that I sat down and worked things out for myself.  In particular, I found the recommendations, or rather the lack of them, concerning the tilting of lenses to be quite mysterious.

Being a sometime mathematician, I was familiar with projective geometry, and used this as a springboard.  Projective geometry grew up as a formalization of the things artists such as Raphael and Da Vinci learned to do when they first drew scenes using perspective.  The ideas are now taught in every drawing class. In any case, it is possible to work out much of geometric optics from this viewpoint, and the notes that I made as I thought through these problems are available here.

It is important to note that this purely mathematical approach is lacking, since quite a bit of geometric optics requires a more substantial physical basis. For example, I have a section in the notes on diffraction, which may not be approached from projective geomery. In addition, the projective geometric approach knows nothing of real lenses, their aberrations, nor indeed of the fact that they have thickness.

The basic file containing my notes is a pdf file that may be read with the aid of the Adobe Acrobat reader.  I have also zipped the pdf file, making a smaller download.

The reader should be warned that these notes do not comprise an exposition or tutorial but are simply a set of notes that were made while thinking through the problems. They are somewhat dense, and not recommended reading unless one really has to know. They give the equations used in preparing the programs available from the Software page.

From time to time I add to them, as I encounter a new problem, and since I make many errors, I also correct things. I will be most grateful to anyone who tells me abut my errors.

DOF Exposition

A frequently question is, “do large formats have smaller DOF than smaller formats?” The answer is both yes and no, as explained in this pdf document.  I also explain why small formats have larger resolutions than large formats.

The Zone System and Digital Prints

An important aspect of The Zone System is the control of negative contrast by adjusting the development parameters. A densitometer is used to measure negative densities which are then plotted in order to calibrate the process. This paper discusses the use of a scanner instead of a densitometer.  Since the document is short, only a pdf file is available.