• Neon tubes

    Neon decoration on the top of a restaurant building

  • Fluorescent lights

    Fluorescent lights on a building

  • Tesla Model S

    Daytime running lights on a Tesla Model S car

  • GMC Acadia

    The tail lights of a GMC Acadia SUV

  • Moths

    Two moths near an outdoor light

  • Venetian

    The Venetian Hotel in Las Vegas

  • Hard Rock Cafe 1

    The Hard Rock Cafe in Las Vegas

  • Hard Rock Cafe 2

    The Hard Rock Cafe in Las Vegas

  • Christmas

    Christmas lights on trees

  • Christmas 2

    Christmas lights

  • Monitor

    A CRT computer monitor

The Book

Book front cover

The ultimate resource:
A Field Guide To Time-Varying Light Sources

Learn more...

Purchase the book on Amazon!


Canon EOS 70D, public domain image

The photographs on this site and in the book are visually stunning. Photographing time-varying light sources is surprisingly easy.

Find out how...

On The Web

Guest blogger on Tristan Gooley's The Natural Navigator

Featured on Atmospheric Optics Picture Of The Day

Featured Artist on Light Painting Photography


Dan BennettI'm Dan Bennett and I'd like to welcome you to the Time-Varying Light Sources web-site. Observing and photographing time-varying light sources is a passion of mine, and the book is — as far as I know — the first and only book devoted to the subject. This web-site has some resources to get you started on this fascinating new way of seeing the modern world. And if you're a photographer, check out the photography section! Enjoy your time here, and I hope you catch the passion!

Most recent blog entries

  • Exhibiting artist at a coffee shop
    Written by

    I'm excited to be the exhibiting artist this month at the Land Of A Thousand Hills coffee shop in Roswell, GA!

    These photos are all from my time-varying lights project, and were selected from my online gallery: (where you can order prints if you don't happen to be in Roswell, GA... laughing)


    Written on Thursday, 02 June 2016 19:02 Read 1203735 times
  • Arcturus - twinkling star
    Written by

    Two nights ago I took a photo of the star Arcturus, using my Canon 70D camera with a 200mm zoom. The exposure time was 1.0 second, during which time I hand-held the camera and moved it during the shot. Here's the result.

    The trace shows a massive number of variations (over 800!) of brightness and color. This is scintillation, better known as twinkling. Our eyes aren't able to see all these variations because (a) they're too dim, so we don't see the colors, and (b) they're too fast, so we see only the largest and slowest variations in brightness as twinkles.

    The cause of these variations is atmospheric - the star itself is NOT twinkling! If you took a photo like this from the International Space Station, it would be a constantly bright, slightly orange line with no variations in color or brightness.

    This type of photography is really easy... go try it!

    A 1-second trace of Arcturus' scintillations

    Written on Friday, 11 March 2016 11:46 Read 14794 times

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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.