Using TPE Desktop Web App, Part 1: Basics

Welcome to the first in a series of tutorials on how to use The Photographer’s Ephemeris Web App.

TPE was inspired by a number of events during 2008: (i) a winter weekend workshop photographing at Dream Lake in Rocky Mountain National Park with Glen Randall which opened my eyes to how to plan landscape shoots using topographic maps, compass, protractor and calculator; (ii) going to shoot Dream Lake again a few months later, and realizing I hadn’t planned properly and (iii) heading up to Loch Vale, a much higher lake in RMNP, for a shoot that was a total bust.

After all that hiking (and not a lot of photos to show for it), I realized the importance of proper planning. I reasoned too that I would rather plan at my computer than purchase maps for every location I intended to visit in the world. Finding no tools that combined all the right data or which worked on a Mac, TPE was born.

The screen layout

You may want to print out the TPE Quick Start Guide as a reference or print out this tutorial and follow along while using the web app. Let’s start by taking a look at the basics of the screen layout.

The most important thing of all is the primary position marker: the red pin. You can drag this freely to exactly the point you need. All information generated within TPE is taken from the position of the red pin.

Top left of the screen the current selected date is shown along with the time zone of the current red pin position and difference from UTC(universal coordinated time – effectively the same as GMT). You can change the selected date using the date selector; use today in the calendar to set the date to that of your computer. Alternatively, use the previous and next day buttons to change the date one day at a time. Use the now button to move to your computer’s current time displayed in the time zone of the red pin position.

Top right above the map is where the elevation above sea level and latitude/longitude of the current red pin position is displayed.

Under the map the events timeline shows the days’s events: times and directions of sunrise, sunset, moonrise and moonset (where they occur) twilight times, moon phase and new moon visibility information. On small screens you can scroll across the events timeline to view all of the day’s events.

At the very bottom of the screen the chart shows 24 hour sun and moon altitudes in graphic form. You can Drag the time slider to adjust the time and see the azimuth and altitude information displayed numerically in the legend.


  1. The red pin
  2. The current selected date and time zone
  3. The date selector
  4. The previous, now and next day buttons
  5. Elevation and latitude/longitude information
  6. The events timeline
  7. The chart, time slider and legend


Radiating out from the red pin on the map you can see the azimuths (relative to true north) of sunrise (yellow line), sunset (orange line), moonrise (light blue) and moonset (dark blue). Using the previous and next day buttons you can see the azimuth of an event change over time. The azim

The thinner coloured lines radiating out from the red pin correspond to the azimuth of the sun or moon at the time selected on the time slider at the bottom of the chart. Click and drag the time slider to see the azimuth and altitudes of the sun and moon change over the day.

Finding a different location

I’m guessing you’re probably not planning a shoot in Timbuktu, so let’s find somewhere else.


  1. Click in the location text field above the map and type the name of the place you are searching for


We will recreate the trip I took in 2008 (but for a date in 2014). Start by typing into the location text field the name of the closest town: Estes Park, CO, USA

Press enter to begin the search, or click the search button adjacent to the text box (magnifying glass). Google Maps will find the closest match to the specified location and reposition the map and red pin to that place.

Where possible, specify a county, state or province as well as the town name, in order to ensure the best match. After all, there’s Paris and there’s Paris, Texas.

The new location

OK. Now we’re in Estes Park, Colorado, USA near the east entrance to Rocky Mountain National Park. There are few things to note:

  • The elevation and lat/long have updated reflecting the new location
  • The red pin lies over the town of Estes Park
  • The time zone has changed to ‘America/Denver’. TPE will automatically determine both time zone and daylight saving rule for any place and date you select


  1. Elevation and lat/long information
  2. The red pin
  3. Time zone information


Moving into the park

Let’s assume we’re going to shoot sunrise at Dream Lake. You can manually pan around the map, zoom in and out and drag the red pin to a precise position.

I’ve moved the red pin to the eastern shore of the lake, from where a photograph of Hallett Peak and Flattop Mountain may be composed.


Where will the light fall?

The yellow sunrise line terminates at the red pin position, but our subject lies to the west. As you drag the time slider the sun and moon +6° shadow circle will appear (you can find out more about that feature here - but it's fine to leave it for later too).

I’ve set the date for Saturday 19 July 2014. Look in the timeline and you can see the sunrise is at 05:49. Clicking on this event in the timeline sets the selected time of day to that moment. Use the time slider to advance the time a couple of minutes (or click once on the slider and use your keyboard cursor keys to advance in one minute increments).

The dark line overlaying the sun extension line is the sun shadow line. Advance the time slider to see this shadow line shorten as the sun gets higher in the sky. Notice too that once the sun rises above +6˚, the circle turns black. The yellow circle is just a visual way of indicating when more golden light is typically available.

Click the sunrise event in the timeline again to go back to sunrise and advance the time slider by a couple of minutes.


  1. The +6° shadow circle is shown as the time of day is adjusted with the time slider
  2. The sunrise time is shown in the timeline
  3. The time slider

On this date it’s clear that the rising sun will come from the north east providing imperfect illumination of Dream Lake and the valley walls above. Perhaps this is not the perfect time of year for the image…

(Alternatively, in the above example, you could reposition the marker farther up the valley to see where the light comes from. There are other good reasons to take this approach too, which we’ll cover in a subsequent tutorial.)

A better date

Let’s skip a few weeks ahead to Saturday 13 September 2014, using the date selector or advancing day by day using the next arrow. As we adjust the time of day, we can see that the rising sun will illuminate the drainage above Dream Lake perfectly, providing the possibility of good light conditions.

The sunrise this time is 06:42, great news! That means you can also have a slightly longer lie-in and still make the shot!


  1. The date selector
  2. The next arrow

Saving the location

Once you have a location identified, you may wish to save it for future use.

Click the bookmark button to the right of the search button on the location text field, this opens the locations page with your location saved at the top of the list.

The name of the location is Google’s suggested name for the red pin position.You can rename the location by clicking once on the name and typing in the field, then clicking the tick to confirm the name change.

You can also delete a location by clicking the trash button and add notes to the location by clicking in the notes field.


  1. The name field
  2. Confirm the name change by clicking the tick button
  3. The trash button
  4. The notes field 

That covers the basics. The same principles apply to any location you want to scout, including cities (for example, when will the full moon rise along 42nd Street in Manhattan).

You might also enjoy “Understanding Light with The Photographer’s Ephemeris” co-authored with renowned landscape photographer Bruce Percy. It’s available through Bruce’s web-site.

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  • 0
    Deon Kotze

    Good day. My TPE for Web on my laptop opens everytime on the date Friday July 2014. I change the date to today...but next time it opens in 2014 again. I also change the loaction in which it opens to Cape Town...but next time it opens at Timbuktu again! I dont mind  so much about changing the date but is there no way to set it that it opens in the same location every time? Thanx 

  • 0

    Hi Deon - please see this article. Basically, the bookmark you have saved includes both date and location - if you remove that part, the app will always open at current date/time and last used location.

  • 0
    Deon Kotze

    Hi Stephen. I must be missing something. I did check the article but the writing in those screendumps are too small. Anyway..when I bookmark a place it goes straight to the "locations" and there I cannot delete part of it.....only all of it. And there is no date to be seen in the bookmark itself. And then the article says you must access that bookmark and the app will open there.....what is the use of that then....I want the app to open at a spesific bookmark every time...looks like it cant be done then. 

  • 0

    Hi Deon - the short version is this: after you bookmark the TPE web app, edit the bookmark so that it reads - you should delete all the stuff appended to the end of the bookmark, as that refers to a specific place and time. If you're still having trouble, please email us or create a ticket via the help center portal.

    PS. I've made the images in both this article and the one about opening in wrong locations click-to-enlarge. I'll have to work through the other articles to update them gradually.

    Edited by Stephen
  • 0
    Deon Kotze

    Hi Stephen. Stupid me...thanx for making the pics to enlarge...I got it right now :-) stupidity...the answer was in the word "bookmark"...anyway I am sorted Thanx!

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