I find these apps very helpful...
Artist's Viewfinder, Mark II
For iOS, US$30/€33
As the first photo below shows, this is a digital Director's Viewfinder. Fairly new to the app, I have it on my iPhone and find it invaluable for scouting. If I like a particular view with a particular focal length, I can capture it from the app for later planning. It sure is a step up from a wire or cardboard frame and a piece of string. It looks like this app has been around for several years, and it's actively developed. No instructional videos on YouTube, but there's a thorough 75 page manual. For me, the performance easily justifies the price.
Photo Pills and PlanIt!
For iOS and Android, $10
These are two of the leading apps for planning astronomy photographs. They're also brilliant for planning an outdoor shoot if you want to know the path of the sun or moon and where either will be, at a given time, in relation to your camera and subject. Photo Pills was used to plan the second photo below, telling the photographer in advance exactly where the moon would be in relation to his camera, and when. Want to know what days of the year a specific phase of the moon will be in the position in the photo? Or, when you can photograph Manhattanhenge over the next year, and what the view will be from a given position? These apps will tell you.
The developers of these apps are in competition and they are both proactive on enhancements and new features. Each app has its adherents. There's a view, which I share, that Photo Pills is more intuitive; or, put another way, that PlanIt! has a longer learning curve. Both have YouTube channels with detailed instructional videos. I like the presentation style of the Photo Pills videos, but some may prefer the more businesslike PlanIt! videos. I have both apps, due to curiosity and because they're inexpensive, but you only need one of them. These apps offer a lot of information. They're OK on a phone screen, but I prefer to use them with the larger screen of an iPad.
Artist's Viewfinder Screen with User Specified Frame Lines
Photograph Planned with Photo Pills
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