Photophys.com: The Science of Photography

I have completed Chapter 9 on understanding compound lenses, and I am now getting help with proof reading.  Also, I have updated the Table of Contents.  The new version is available here.

New figures have been added to Chapter 4 (pdf, 188KB) to illustrate changes in image size and perspective, and work is proceeding on Chapter 9: 

 Tentative Title for Chapt. 9:

 Coming to terms with real (compound) camera lenses

(Nodal planes, entrance pupil, stops, and all that)

I expect to be able to post Chapter 9 in a couple of weeks.

I was happy that Nathan Myhrvold noticed my essay “Lens Equivalents,” on Luminous-Landscapes and that he took time to comment on it.  Our discussion/debate was a lot of fun, but a face to face discussion would have been much better.  Debates online never seen to be completely satisfactory.  Probably because feedback is delayed, and one cannot see immediately which points are being accepted and which are not.  Also, I suspect participants do not read carefully enough comments that appear to contradict their own.

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Here is a draft of Chapter 15:

The Limits of Human Vision – How Good Does a Photographic Image Need to Be?</o:p>

 </o:p>(pdf, 214 KB)

Biology is not my forte, but I do like to learn things.  I find the design and operation of the human eye to be fascinating and certainly relevant to the design of photographic equipment.  I am on thin ice here, so please help me with your suggestions and criticisms.  If you prefer to contact me by email, check the “About page” in the upper left hand corner.</o:p>

This post offers a draft of Chapter 8:

Chapter 8:  How to Make Lenses That Are Good Enough for Photography

(pdf, 276 KB)

This one concerns the complexity of modern lenses required to correct aberrations, minimize flare, etc.  It is fairly brief, but it covers a lot of ground.  As always, comments are appreciated.  I would certainly like to correct errors and misconceptions; but I also need to find out what parts are not understandable as written.

With this post I am presenting:

Chapter 7:  What is behind the rules of optics?
(pdf, 98KB) 

This chapter deals with modern physics and the rules of optics, and it provides a glimpse of the strange universe we live in.  It is far removed from practical photography, but it does introduce ideas that are useful in understanding optics in general and, in particular, the interference effects we will encounter with lens coatings.  If this kind of thing does not interest you, feel free to skip ahead to lens design issues, etc.

 </o:p>The updated, but still tentative, Table of Contents can be found here.

Chapters 4, 5, and 6 are posted.  Comments, are appreciated.
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Resolution tests are presented for different pixel sizes at a variety of F-stops.[Read More]

With this post I am making available the following Chapters:

1.  What is photography

2.  What is Light

3.  The Camera

I would appreciate any comments.  Additional chapters will follow in a few weeks.

Welcome to my new BLOG!  I am launching photophys.com to provide a forum for the discussion of science and technology related to photography, AND to help me develop and improve a book tentatively titled “Science for the Curious Photographer.”  I also plan to discuss and test interesting equipment in cases where scientific principles are involved.  The first example will be tests of diffraction broadening effects for different size sensors.

The book is almost half written at this point, but I expect to rewrite many of the chapters to improve the English, make difficult material more accessible, and to get rid of errors and misconceptions.  I plan to post a new chapter every few weeks in hopes of getting comments, suggestions, and corrections.  In fact, a couple of chapters are available now.  The chapters will not necessarily be posted in serial order.

As the book progresses, I find that the topics expand; and the final result is more massive than I expected.  Yes, that does mean it tends to get heavier as well as occupying more space.  On this first pass, I am trying to get everything right and to be reasonably complete.  Later, I will attempt to simplify the presentation and perhaps put more difficult (mathematical) parts in boxes, or even in appendices. But I need advice about which parts are not clear and where changes are necessary.  To make this more concrete, I list the tentative table of contents below:  

Science for the Curious Photographer
(Digital Photography for Smarties)
Here smarties are the opposite of dummies, not smart alecks

1.  What is photography?  (Definition and history)
2.  What is light?  (History, waves and photons)
3.  The camera - an introduction  (lenses, film, sensors, focal length, F-stop)
4.  Images: What is perspective? (Perspective point, field of view, normal lens)
5.  Why does a camera need a lens? (Pinhole camera analysis, diffraction, lens advantages)
6.  Elementary optics.  How do lenses work? (Hero's law - reflection, Snell's law -  refraction, refractive index, and Fermat's principle of least time)
7.  What is behind the laws of optics? (QED made easy with illustrations)
8.  Photographic lenses.  (Aberrations, dispersion, coating, characterization – MTF)
9.  Special purpose lenses:
    - Wide angles, Telephoto, Fisheye
    - Close-up photography (Macro lenses, extension tubes, add-on lenses, etc.)
    - Telephoto lenses, tele-extenders, etc.
10.  Depth of field, diffraction, etc.
11.  Infrared  and UV photography
12.  Capturing Images.  (Film vs. digital, sampling problems, grain vs. noise, exposure, film and sensors CCD, CMOS, and Foveon, definition of ISO sensitivity)
13.  The Limits of Human Vision: (The eye, acuity, detection of color)
14.  Colors and perception.  (Psychophysics, trichromacy, opponent theory, the primary colors, the chromaticity CIE color space)
15. Color cameras: Capturing color, color management (how to make the image appear the same on the screen and in prints)
16. Computer enhancement of images:
      Panarama, Helical focus, Sharpening, Noise Reduction, HDR, Super-resolution through the combining of images, etc.
17. Composition: What is pleasing and why?
18. Illusions and how they can be used in art and photography (patterns that appear to move, luminance matching, etc.)
19.  Formats and conversion: RAW to full color, etc.
20.  New Technology:  What is on the horizon – sensors, motion detection, etc.
    - Plenoptic cameras
    - Negative index of refraction for diffractionless images
    - Motion deblurring
    - High-resolution video capture

© Charles Sidney Johnson, Jr.

The bold face headings indicate that either the parts have been written or that there has been a lot of work in that area.  The chapters are basically essays on connected topics.  The first chapter “What is Photography” is available now.  It is very light, but weight increases rather rapidly so that by chapter 6 there is a fair amount of math.  However, I hope to present things, with your help, so that it is will clear what claimed and what is demonstrated even to those who do not choose to work through the details.

    So I invite your comments, criticisms, etc.

Who am I?  The following paragraph was written for Luminous-Landscape to accompany my recent essay on Lens Equivalents.

Charles S. Johnson, Jr. is Professor of Chemistry Emeritus at the University of North Carolina at Chapel Hill.  He has authored approximately 150 research papers as well as books on laser light scattering and quantum mechanics.  His interest in photography goes back to the 1950’s when he started documenting his high school and hometown and doing freelance work with a Rolleicord III and a Zeiss Ikonta 35.  However, for many years his career in science left little time for serious photography.   Now in addition to enjoying nature and travel photography as a hobby, he is making use of his science background to write a book that reveals the science behind photography.  This book deals with fundamental questions such as the behavior of light, how lenses work, sensors versus the human eye, our perception of color, and the art of composition.  He is also presenting some of this material in essays on timely topics in digital photography.  The book and the essays are, of course, aimed at those individuals who enjoy understanding how things work.