Dan's mugshotDaniel H. Bennett was born in London in 1965 and lived in England until moving to the United States in 2000, settling in Northern Colorado.

His interest in vision and observation of the behavior of light has been life-long. On a trip to France as a young man his hosts called him “Monsieur Tête-en-l’air” (Mr. Head-in-the-air) due to his always watching for halos, rainbows, sun-dogs (parhelia), etc. He was particularly influenced by a book written in 1939 (published in English in 1954, Dover) by Professor M. Minnaert, called The Nature of Light and Colour in the Open Air. A Field Guide to Time-Varying Light Sources was conceived as a modern successor to that book, and adopts a similar approach, while revealing the secrets of modern light sources.

Daniel is married with four children, a motorcycle and two accordions.

Buy the book!

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 CreateSpace!

Purchase the book on Amazon!

The Blog

Here's my blog, where I'll write articles of interest, things I've learned, tutorials, suggestions for lights to go look at, musings, etc.

Dan Bennett

Thursday, 23 April 2015 08:31

Price drop

I've decided to drop one of the distribution channels that my book could - maybe - be sold through. That has allowed me to drop the list price from $32.99 to $25.99. This price change takes effect immediately on Createspace's page, but may take a day or two to be reflected on Amazon's page.

Wednesday, 04 March 2015 19:06

Featured on Atmospheric Optics website!

Exciting news regarding my book: Today, it's being featured on the Atmospheric Optics Picture Of The Day website! Although most of the book isn't concerned with atmospheric optics per se, the section on twinkling stars certainly qualifies; and the website's charter is pretty broad, so it fits right in.

The permanent link to the page is

I asked the guy who runs the site (in which I had a photo published a while ago) if he would feature the book, and he's done an excellent job! He obviously had a lot of fun building that collage.

His audience is my audience, so I'm hoping this will help to get the book some targeted publicity.


Saturday, 07 February 2015 15:23

Welding and laser cutting at Walker Mowers

A mower from WalkerI had the chance to take a tour of Walker Manufacturing (home of the high-end commercial mowers) this week. This was my first chance to see electric welding equipment in action, so I took the opportunity to eyeball-jiggle at the bright welding spot. Sure enough, it's time-varying, but it turns out it's varying in two ways:

  1. It fluctuates in brightness a lot, as you would expect when welding is taking place.
  2. But it also flashes on and off rapidly, probably at 60Hz or 120Hz, which shows that its power is modulated by the A/C cycle.

Obviously, one shouldn't do this for too long; but actually, eyeball jiggling has the effect of reducing the amount of energy reaching any one spot on your retina. As long as you don't stare at it like a deer in the headlights, you'll be fine.

I also had the chance to see a heavy-duty laser cutter in action. It's cool! It takes large sheets of steel, which can be up to half an inch thick and weighing up to 2000 lbs, and it cuts shapes out of them as if they were butter! I was able to observe the bright spot right where the cutter is melting the steel, and sure enough, there was a regular variation in brightness. It seemed quite fast, maybe 200 or 300Hz, though it would need a photograph to allow one to measure the frequency. I'm pretty sure I wasn't seeing the laser itself, but variations in the temperature of the melting spot, maybe. The variations were fairly subtle.

It's always worth jigglin' at stuff - you never know what you might see!

Wednesday, 28 January 2015 16:17

A stack of books

20 copies of the book arrived today - the first time I've seen the final product in physical form. This is a wonderful moment for me... the tangible fruit of a lot of labor!

Monday, 26 January 2015 22:46

Now for the marketing...

It seems ironic (and a little deflating, frankly) that now that the hard work's done, the hard work starts! Writing the book was a labor of love, and it had a very clear end-point in view: finish the book and get it published. That goal has now been fulfilled, which is great! However, the biggest down-side of self-publishing is that the marketing of the book lies squarely on my own shoulders. Of course, there are ways to do this, and I've already set some wheels in motion, which should hopefully bear fruit down the road. But it would be wonderful if something happened to make it "go viral" - always the marketer's dream.

The biggest challenge with this book is not that it's not interesting or captivating - everyone who's seen it says it's both - but that it address a completely new topic, one that nobody even knows exists. How can people be expected do a web search on a topic that they don't even know they'd be interested in?

The key to marketing, of course, is to get the book in front of audiences that are highly likely to be interested in observing time-varying light sources, once they're made aware of the field and its possibilities. To do that, I'm starting to reach out to key people who have websites and/or YouTube channels that a lot of people follow, but which are in closely-related fields, such as observing/enjoying atmospheric optics, or photography. These key people are known as "influencers", and are the lynch-pins to reaching audiences. I'm definitely hoping they'll be able to put some wind under the wings of my book.

Here's to successful marketing!

Comments welcome. :)

Monday, 19 January 2015 17:01

The eBook is cooking...

Well, now that the print edition is out there, I'm about to start work on the eBook for Kindle. It's going to take some work, because, unlike a novel, this book has over 300 pictures and captions! Laying all of that out in a reflowable format so that it works on any size of device without the captions and pictures getting horribly separated from each other will be a challenge! Thankfully, Adobe InDesign (which is what I've laid this book out in) does a pretty good job of exporting to the epub format, which is one of the formats that Amazon can accept for a Kindle publication. It's going to take a little while to make sure the output is exactly what I want, but I'll get there.

And... the book has already appeared on Amazon in the US and in the UK! Amazing - the CreateSpace process says it'lll take 3-5 days. Maybe that's for the non-English European sites. For example, le livre ne se trouve pas au site français. Oh, sorry... The book isn't on the French site yet. :)

Sunday, 18 January 2015 21:41


Today my book went live on! After four years of working on it (not all the time, of course), and a major push over the last three months or so, it's finally a Real Book! With Pages, and a Cover and Everything!

I am sooo excited!

The book is published through CreateSpace, which is a division of Amazon which allows people to self-publish. The cool thing is that the book is printed on demand - i.e. when someone orders a copy, a copy gets printed, bound and shipped. This is wonderful, because there's no need for me to fund a print run, no up-front inventory, or anything!

In a few days' time, it'll appear on Amazon's websites in the US, Canada and Europe.

This book is totally a labor of love - observing time-varying lights has been an interest for me all my life. So it's a wonderful milestone in my life to see it in print. I am one happy guy. :)

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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 © 2015 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.