It’s all about the light: The Photographer’s Ephemeris

It’s all about the light: The Photographer’s Ephemeris


Photography is a blend of art and science: nature and numbers. Photographers must master the technical and the aesthetic in pursuit of capturing their images. And when it comes to knowing where and when the sun or moon will appear, a high tolerance for numbers certainly helps!

Until recently tables of numbers were the standard way to obtain sunrise/sunset times and information on moon position and phase.

But we photographers are visual people and this information only matters to us in the context of our photographic subject. Wouldn’t it be better to see how the light will fall on the landscape visually?

This is where The Photographer’s Ephemeris (TPE) comes in.

photographers ephemeris 1.png

An ephemeris is a table of numbers giving the position of astronomical objects in the sky over time. The Photographer’s Ephemeris gives the raw data, but goes on to display it visually, overlaid on Google Maps, allowing the user to see the angle of the sun and moon for any time and date and any location on earth.

While originally conceived for landscape shooters, all outdoor photographers can use TPE to plan the best locations and times for a given shot.

Using TPE in practice

Mesa Arch in Utah’s Canyonlands National Park is one the most spectacular sights of the desert southwest. Spring is a beautiful time to visit Canyonlands but is it the best time to shoot Mesa Arch? We can investigate using TPE.

This location is renowned for the spectacular glow of the rising sun striking the sandstone wall below and bouncing up to illuminate the underside of the arch.

The most intense colour is seen when sun hits the wall immediately after sunrise. Let’s see how this might work during a spring visit in April:

photographers ephemeris 2.jpg

TPE for iPhone shows us that the sun will rise at 6:38 am at an azimuth of 75° (from north). So far so good. But using TPE’s geodetic calculator, we can see that the rising sun must first crest the La Sal Mountains to the east. Dropping the grey pin on the mountain peak shows us that the elevation angle from our shooting location is +1.2° – not much, but enough to cost us roughly the first 9 minutes of sunlight.

Can we do better? Let’s check a date much earlier in the year – say, January 1:

photographers ephemeris 3.jpg

Things are looking better: the sun rises far to the south of the La Sals, and with no obstruction on the horizon, we get direct light on our subject pretty much from the time of sunrise:

photographers ephemeris 4.jpg

Intense light, a longer lie-in, no crowds, plus fresh snow on the red rock: all round, a much better proposition.

TPE Top 10 Tips

1) Scout your location ahead of time

At your desk… Use TPE for Desktop to plan your shoot ahead of time. Choose the best map mode for your subject: Map for cities, Satellite/Hybrid for details of particular buildings, Terrain for landscapes.

2) Look for starred dates

TPE for Desktop shows an asterisk next to dates when a full or new moon will be low on the horizon near the time of sunrise or sunset: these are often the best days for images including the moon.

3) Pre-plan your shooting position

Use the time of day slider in Details mode to check the angle of sun at the time of game kick-off, or when the bride and groom will emerge from the church. Ensure you have the optimal shooting position for the critical moment.

4) Find a starry, starry night

Look for times after or before astronomical twilight and compare with the times of moonrise/set to find a truly dark time for astro-photography.

photographers ephemeris 5.png

5) Double check the angle of view

Use the secondary map pin (gray) to check the elevation angle from your shooting location to your chosen landmark. This can indicate what focal length lens you will need to accommodate the subject in the frame.

6) Don’t be kept in the dark

Use the time of day slider and the secondary map pin in combination to check whether the sun will be hidden by a nearby hill or ridgeline. Scrub back and forth to see the track of the sun (or moon), choose your moment, but then double check by aligning the secondary map pin and comparing the angles.

7) Adjust your horizons

Use the secondary pin to set the elevation at the horizon. TPE will tell you how far you can see on a clear day, plus it will fine tune rise and set times – this can be important for mountain photography. It’s easy for sunrise to occur 10 minutes earlier due to the height above the horizon – don’t miss the magic moment.

8) Find your favourite city-henge

Use TPE to find the dates when sunset aligns with your favourite city street. Manhattanhenge is probably the best-known example, occurring twice a year in late May and mid-July. Be sure to fine tune the sun position using the details slider so that it’s just above the horizon where you can still shoot it, then check the optimal date for the alignment with your chosen city street.

9) Save your locations

Build a list of your favourite places. TPE doesn’t limit you to a preset list of towns and cities. Once you’ve found your shooting location, you can save the exact spot for future reference.

10) Carry it with you

You can’t always plan in advance. If you need to know all about the light when you’re on the road, TPE for iPhone has the same functionality as the desktop version.

Get The Photographer’s Ephemeris

TPE for Desktop is a free download for Windows/Mac/Linux, available at

TPE for iPhone is available for purchase in the App Store.

Additional tutorials are available at

About the Author: Stephen Trainor has spent the last three years photographing around the southwest US, learning the importance of planning your shots along the way. More at

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Some Older Comments

  • Nusantara June 13, 2013 03:25 pm

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  • Dave Richards February 8, 2011 02:21 am

    Cheers Mark, many thanks for the info. All of what you say makes sense and since I'll be running the desktop version I feel safe trusting the judgement of the many users, including yourself, that have had a trouble free experience.
    By the way, I've had a look around your website and think you have a wonderful 'eye'. I particularly liked the 'Colour of Yesterday' shot...beautiful. Also quite a lot of the natural shots of Arkansas. If ever I get over to the U.S. I must give the area a visit.
    Thanks again

  • ArkyMark February 8, 2011 12:47 am

    That's probably because it doesn't have a "Digital Signature" - a special stamp from Microsoft (or whoever) saying it's approved for your system. This is something MS charges authors for, and not many bother since it's mostly B.S.

    I've run TPE on my XP desktop and Vista laptop with no problems for years now. It needs to access Google Maps through their API so that it can display the maps - which is why it needs access to the 'net. As you move the map around or go to different areas, it will send requests for this new data to Google Maps - but that's about the end of it. As I recall, there's no personal data (like your email address) involved - and I seriously doubt that the simple Google Maps API this app uses could have "unrestricted access to your system".

    You may have to unblock it from your firewall or otherwise OK it's access to the 'net - but it's safe as far as I can tell. Google Maps/Earth, Facebook, Twitter, Flickr and many other online services now offer ways for developers to "plug-in" to the data and content on these systems - and TPE is just tapping Google Maps to do it's trick. Everything else about the application runs and is stored locally - like your saved locations and such.

    But you're smart to be cautious about this - and I can only speak for the desktop app. I haven't explored the smartphone version yet...

  • Dave Richards February 6, 2011 05:13 am

    Hi Everyone,
    Really keen on using this piece of software but having downloaded it I get a message about it putting my system at risk because the publisher is unknown and it would have unrestricted access to my system. Has anyone else had this message and if so did it present a problem?

  • Beau Mitchell Landscapes December 20, 2010 09:32 pm

    I've used the Photographer's Ephemeris on a number of occasions. It comes in really handy before heading to a new location, and saves a lot of time on wasted trips where the light isn't going to be right for the kind of photograph you want. A nice article, too. Thanks!

  • Tom September 3, 2010 04:34 am

    Great tool.

    Has someone ever run it on a windows mobile device?

    I think I'm going to use it a lot.

    Thanks for sharing.

  • jlrsn June 26, 2010 06:21 pm

    i prefer sunseeker, but this'll do.

  • John Green June 25, 2010 12:54 pm

    Brilliant! thanks for sharing

  • Michelle Armour June 25, 2010 10:08 am

    Yay, a post with real info woohoo!

  • PhotoEphemeris June 24, 2010 11:59 pm

    Rob - could you send an example of the problem you're seeing with the moon graph to We haven't had any reports of any issues with the moon data (and have seen a number of high precision shots planned with TPE, for example as seen in the Flickr TPE Group)

  • Rob June 24, 2010 01:49 am

    I use this app and its a great tool but with one issue for me and that the tracking of the moon rising and setting is wrong on the graph. I know this because I use it to track the moon rising from my house,. for the sun its ok.
    I use it in the gulf and you can get great opportunity shots with this tool

  • Dianne June 23, 2010 03:35 am

    I've been using this for about a year and I love it! Great software and useful for non photographers too.

  • Shotslot June 22, 2010 08:35 pm

    What a great piece of software, and actually what a good post too - I shall be using the desktop version but I will certainly be using it, since I've been trying to make myself shoot smarter.

  • Zack Jones June 22, 2010 05:21 am

    I love this app. At first I didn't know why I would want to use it but now I can't live without it. Here's a tip for the deskotp version. Once you find a spot on the map you can hold down the shift key to extend the lines for sunrise, sunset, moonrise and moonset. This is expecially helpful if you wanted to determine the best location to be if you wanted to shoot into a sunrise or sunset, etc. I can't wait for an iPad version.

  • ArkyMark June 22, 2010 01:35 am

    @Chris Morgan :

    It uses the data from Google Maps ... so, whatever they cover. (You need to be connected to the 'net to use it.)

  • Chris Morgan June 22, 2010 01:25 am

    Does it have worldwide data or is is it just for the USA?

  • John Dunne June 21, 2010 06:22 pm

    What a great tool, thanks for bring it to our attention. The fact that their is an iPhone version as well is simply icing in the cake.


  • Karen Stuebing June 21, 2010 04:10 am

    Okay, I used this tool for my Daily Shoot today. Worked like a charm. There is a long explanation about how I didn't want to shoot the sunset because of fog and West Virginia Day being today.

    And it got very convoluted coding the links but there are actually three entries, the first which is here. It is a screen shot of the app. With the long explanation. :)

    I can write HTML but unfortunately I have never had any success here using their XHTML tags so you'll have to copy and paste. If you're interested.

    Or you can click on my name but you have to go backwards with the arrows because it's a blog set up or use the links in the post.

  • Daniel Mc Adam June 20, 2010 08:17 pm

    I use this app all the time it is a must for anyone into photography.

  • Karen Stuebing June 20, 2010 07:37 pm

    This is really cool. I am going to download it to my PC and netbook. Don't have an iPhone and apps.

    Since I live in WV, there are plenty of beautiful landscape photos out there. Different than the southwest, but lovely nonetheless.

    Using light to your advantage as a photographer is critical and high tech tools like this can only help.

    Thanks for the info and the links. This is the first I'd heard about it. Can't wait to try it!

  • John McWhirter June 20, 2010 05:56 pm

    This has to be one of the best non camera gear accessories I have ever seen. I so wish I knew about this 6 months ago before I drove 1/2 hour to photograph a sunrise behind trees.

    [eimg link='' title='Day 19' url='']

    TPE shows a possible trip this weekend as the sun will be just where I want it....

  • Jen at Cabin Fever June 20, 2010 10:57 am

    Wow! This looks AWESOME! I am absolutely going to download this to my iPhone, which always accompanies on my photographic adventures. Thank you for sharing and including a little info about it!

    Cabin Fever in Vermont

    NEK Photography Blog

  • ArkyMark June 20, 2010 09:08 am

    Ironically enough, I just wrote about this on my own blog - and TPE is one of the best apps for an outdoor / landscape photographer I've ever seen! I used to plot this type of data myself using a combo of Google Earth and Stellarium (an open-source planetarium program) - but TPE tells me all the info I need in a single, elegant app. I'm glad to see new versions for smart-phones too.

    This one's a must-have, folks - and I just love it!

  • Nick P June 20, 2010 08:49 am

    This is a great piece of software that I've used for a while and told all my landscape photographer friends about so can strongly recommend it.

    Reasonably simple to use and provides all the info you could need when shooting sunrise or sunset shots.

    All we need now is an Android version ;)

  • Richard Healy June 20, 2010 07:51 am

    Wow! I love it!

    Now I shall have to get a Iphone. Damnit!

  • Danferno June 20, 2010 07:20 am

    This is so coool. Thanks for sharing.