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.