How do you use it...what do you use it for? Is it good for stand-alone phonography?
I use it for my view cameras. I can chose 4x5 option in cameras and pick the focal length according to the lens I have, say 210mm and it will give me that view in the correct aspect ratio, so I can look at the phone and first off work out whether its worth the effort of setting up a large format camera, then I can work out where to potion the camera and whether to use portrait or landscape......a good composing tool.
You can also flick through other lens, to see whats best and use add magnifying adjustments for zooming in.
Thinking about making a clip to hold the phone to the hot shoe, so I can get a better view when using my ancient Bessa 1 6x9 and maybe my 4x5 press camera, by hand held.
It will do 35mm, 6x6, 6x7, 6x8 and 4x5. You can use a lens chart to find the corresponding lens for the same aspect ratio. So 35mm and 6x9 are the same aspect ratio as is 4x5 and 8x10.
You are constrained by how wide the lens is on your phone, my galaxy 4 phone isnt very wide and just shows a shaded area of what it misses.
You can take a photo at any time if you wish.
There are other apps, some cost money and have more features, this one was free. You need to remember to turn it off as it drains the battery when left on.