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The Field Guide is available from Amazon and other outlets.

The book's front cover

ISBN-13: 978-069-236090-3

ISBN-10: 0-692-36090-5

LCCN: 2015900348

Purchase the book on Amazon!


  • Over 300 color illustrations
  • Full explanations
  • Easy to read
  • Observation tips
  • The ONLY book on this topic!

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White bar image thumbnailA JPEG image of a white bar on a black background - ideal for observing the time-varying behavior of computer displays and TVs. Download

Quite literally, this book will teach you to see the world in a completely new way.

A Field Guide To Time-Varying Light Sources is the ultimate resource for observing and capturing the traces of lights which appear steady but are in reality flashing or changing very rapidly. With it, you will be able to see what you've never seen before, and unpack the sometimes complex behaviors of lighting technologies and natural light sources.

Trace of a traditional fluorescent lightTake a traditional fluorescent tube, for example, the kind that flashes a few times when you switch it on, and which buzzes when it's operating. To the casual observer, it appears to generate a steady, white light. To the vision-jiggler, it reveals its true behavior: a rapid alternation between bright, bluish white and a dim yellow or even brown color (see the photo on the right, and this video). This variation happens because of the way the tube works, and because of the AC (alternating current) electricity that's powering it. This book documents and explains this effect, and covers a host of other light sources that also show variations when observed correctly.

The table of contents (see below) reveals the structure of the book, which essentially takes the reader on a journey. The first part is instructional:

  • What are time-varying light sources?
  • How to observe them with the naked eye, or with a mirror (read more)
  • How to interpret what you see
  • Photographing time-varying light sources (read more)
  • Videography (read more)

The main body of the book is the Field Guide itself, which covers ten categories of time-varying light sources, richly illustrated with photographs and documented with observation tips and explanations of the behaviors you might see. One of these sections is a portrait of Las Vegas, which is probably the most rewarding location on the planet for the aficionado of time-varying light sources.


Sample pages

Here is a selection of pages from the book, beginning with the table of contents. Most browsers will show this in a scrollable window. If your browser doesn't show it, you can download the PDF here. Additionally, the viewer below may not show well in a mobile browser.


300+ illustrations

Most of the photos in the book were taken by the author, specifically for illustrating the book. Over 3000 photographs were taken!

Full explanations

The text describes every light source, how it varies, and how it produces the pictures that go with the text. Every image has a caption that tells you everything you need to know.

Easy to read

It isn't written like a scholarly thesis! Easy-to-follow text explains concepts, technologies and techniques without becoming too hard to swallow.

Observation tips

Observation tips lead the reader to get the most out of the book.

Totally unique

This is believed to be the ONLY book ever published on this subject! It genuinely adds to the sum of human knowledge.

Site design

This site is powered by Joomla! CMS. The template is "Cast" from Joomlage, modified here and there. The gallery is powered by RokGallery. All design by Dan Bennett.


All content on this website, including images, videos, text and material from "A Field Guide To Time-Varying Light Sources" is © 2023 Daniel H. Bennett / / A Bear Peering Round A Rock, and may not be reproduced without permission. All rights reserved to the extent of applicable law. Exceptions: third-party images, which are credited as applicable, third-party embedded videos and public domain images.