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.

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:

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:

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:

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.

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 http://photoephemeris.com

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

Additional tutorials are available at http://photoephemeris.com/support

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 http://stephentrainor.com.