Helios, the handsome Greek god who drove the chariot of the sun across the sky each day is now in your pocket! The Brits at Chemical Wedding have introduced an advanced sun tracking app for the iPhone/iTouch called Helios. Far and away one of the best pieces of sun tracking software I've seen since Clear Day Software's SunWhere in the 1990s.

Helios allows the user to plot any given date and any given position, from their current GPS position to a pre-selected city around the globe to a custom GPS entry, and determine the exact position of the sun at any given moment of the day.

Once you have a date and position, the program has three primary interfaces: the heliometer, Sky View and a clinometer.

In heliometer mode, the display shows 3/4 of a compass and a yellow ball indicating the sun. There are indicators on the compass for the exact azimuth of the sunrise and sunset and sections highlighted in orange for pre-dawn and twilight. Where night falls, the compass is black. In the center of the compass are the selected day and date. Next are three boxes showing the exact time and compass position of the sunrise, the number of hours and minutes of daylight for that given day and the exact time and compass position for the sunset. Below that is the location you're receiving data for, based on your GPS or a preset location. You can easily set your favorite locations and scroll between them.

On the compass is an arrow indicating "high noon"—or, rather, the point at which the sun reaches its apex for the day. You can touch and drag the sun icon on the compass to any specific point and the app will calculate the exact minute of the day the sun will be in that compass position. At the far left of the heliometer is an indicator showing the sun's elevation in the sky (relative to the horizon) for any given moment. In addition, and I've never seen this before on any sun tracking software, the heliometer also gives you a shadow length ratio. For any sun position, you can calculate the length of an object's shadow by multiplying the ratio indicated by the height of the subject. The compass dial, itself, can also be rotated if the amount of daylight exceeds the 3/4 shown on the screen.

Helio's second interface is the Sky View. Here you have the same information and control as the heliometer, but presented in a different manner. You're looking at a sort of 2D representation of the sky, as imagined if you were lying on your back staring up. It's a bit confusing to understand, at first, but once you discern how to read the Sky View, it provides a lot of information at a glance.

Finally, the clinometer might be one of the handiest tools in the program. Utilizing the accelerometer function of the iPhone/iTouch, you sight along the edge of the iPhone to a point in the sky, touch the clinometer to measure and touch again to lock it and it will give you the exact time of day that the sun will be at that elevation. Want to know when the sun is going to rise above those trees at a location? The clinometer will instantly tell you. Want to know how long you'll have direct sunlight at a location before it passes behind surrounding buildings and shades your area? The clinometer will instantly tell you.

The tools available in this application set are incredibly intuitive, powerful and informative. People might not think they need such a tool, but imagine the wealth of information you can derive from this application in your pocket. Are you shooting a daytime interior and want to know if and when sunlight will come through a specific window? This application will provide you with an exact window of time that you'll have the light you want (or don't want) coming through that window. Are you entertaining a number of potential locations for a shoot (perhaps weighing those tax incentives)? Take a look at Helios to see the number of daylight (or night) hours and minutes you'll have each day for shooting. I was discussing potential locations for a feature shoot and Alaska was suggested. I was able to quickly consult Helios and see that we'd have 18 hours of daylight! That seems really great, until you look at the number of nighttime exteriors we had in the script and realize that we'd only have six hours of darkness each night to work in! In less than 60 seconds I could see the problems that would arise two months later 3,600 miles away and begin to discuss solutions or alternatives without ever leaving my desk in Los Angeles.

Since downloading Chemical Wedding's application, I have used it on almost a dozen shoots—not including my intensive testing—and it has never failed me. The functions are intuitive and easy to use. Helios has a very beneficial (along with witty and entertaining) help function, but it requires an Internet connection to access. If you're on an iTouch and out of WiFi range or your 3G is not getting connected, you cannot view the help.

Once you have data for a given location and day, you can use the e-mail function to send an extremely detailed report to yourself or someone else for printing.

If you have an iPhone 3Gs, Helios integrates with the compass function, but I was unable to test this feature myself.

If I have anything to complain about it's really only one thing: the app works in landscape mode, but it functions in upside-down landscape—as compared to most applications. It requires you to turn the phone clockwise, as opposed to counter-clockwise as with most every other application. But, I guess since a couple of Brits made it, it makes sense they're on the wrong side of the road. It is, admittedly, an extremely minor complaint.

All in all it's an incredibly powerful application that helps tame the brightest and most stubborn light source on the planet.

Helios Sun Position Calculator v2.1
3.4MB
Chemical Wedding
$29.99
iPhone OS 3.0 compatible, iTouch compatible