I don't know if this is the right place for this post, if there's a better one let me know.
It seems that whenever I come across a really good shot, the Sun is inevitably in the worst possible position. (You'll find this phenomenon listed under "Flotsam's Law" in the Focal Encyclopedia).
As it is now, I just make a mental note to come back at a different time of day when I guess that the light will be better but this is really a rough estimate especially if the position is critical and I have to hike and get set up before the light peaks.
What I would love to do is be able to take a compass bearing on the scene when I'm there and the light is wrong and then, at home, using a calculator or computer program, determine exactly when the sun will be in it's desired position in relation to the scene so that I can return in plenty of time to set up and catch the light.
Does anyone know of if a program or calculator like this exists? The only ones that I can find only deal with the night sky.
I carry a PocketPC type PDA with me when I'm out shooting. I downloaded a program by Jonathan Sachs (the guy who wrote Lotus 1-2-3 and Picture Window image editor, and a photographer himself, http://www.dl-c.com/) called Ephemeris that is good for this very thing. It will tell you the phase and rise- and set-times of the moon and sun, and will also calculate the elevation and azimuth (compass direction, with magnatic variation inlcuded) of the sun throughout the day selected. It takes a few tries to find the porper time of year for an exact location of the sun, but if you want the angle the next day it will tell you the time. See a description of the program here: http://www.luminous-landscape.com/reviews/...pocket_pc.shtml
Sachs has also written an existing light program, and a depth-of-field calculating program, both for the PocketPC and for the Palm devices.
For the PC there are a number of astronomy planetarium type programs that will do the same thing. Check download.com and search for 'astronomy'.
And to toot my own horn, I've written a (mostly) freeware database applet for recording photo information that runs on the SprintDB database on a PocketPC: http://handango.com/PlatformProductDetail....=1&platformId=2 It contains most fo the functionality of Sachs programs (though slower) except for the ephemeris.
There ARE calculators with programs specifically for photographers, among them also the program you speak about. Although I know this I don't have unfortunately any more info about it except that some years ago it cost about 300$. Long before they came on market I made my own program for a Casio calculator (with algorithmes taken from the official Almanac for computers, final edition 1991) which I used all over the world. It even shows graphically the sun direction so it can be used as an electroinc compass too. It's a very useful accessory. If you go for your own version you can make your own programs - lens subject/ object distances, magnification, bellows extension and filter factors etc. For landscapes you can check on maps at what time you will have the light you need - saves a lot of waiting and disappointment on terrain.
I have been doing this since 1991 using a hand-held global positioning receiver. It is important to know the latitude as the sun arc across the sky will change depending upon latitude, as will rise/set times of both the sun and moon.
I use a Trimble Scout. Once it is programmed with the correct time offset from Greenwich Mean Time (GMT) for the time zone you are working in, it will do the rest as it knows the time from the satellites, and (obviously) can calculate latitude and longitude. It will then tell azimuth, altitude, and compass direction of the sun or moon in 5 minute increments. You can also use it to predict future positions, because it will let you enter a future time and date in the sunrise/sunset, moonrise/moonset function.
This device along with a Brunton Pocket Transit (compass with built in levels to "shoot" elevations) have proven invaluable in many photo situations. You might want to check out the Magellan Platinum. I know it will do sunrise/sunset and moonrise/moonset functions, but I don't know if it will allow entry of future times and dates. It does have a built-in compass function along with its GPS location function. Unlike many hand-held receivers, it does not have to be moving to tell compass direction.
About GPS, I have a Magellan Map 330, and the sun/moon screen will allow you to set whatever date you like, but it will only report the sunrise and sunset times, not the compass direction. There is another screen what will show you the compass direction of the sun is at the moment, but that screen will not show future sun positions.
I'm thinking that the sun/moon screen will progress in features from the Map 330 version to ones more useful to landscape photographers, but I haven't been following the latest Magellan and Garmin models to know how they've developed.
Thanks to all.
This is exactly the information that I needed. Now I know that there are several existng solutions to the problem. I'll look into them all and hopefully settle the method that works best for me.