Ever wonder what a scene would look like in a frame? Ansel Adams used to put the thumb and index fingers of both hands to make a rectangle or a square to frame a scene. There's a DYI version I think is better. The viewfinder in the photo is made from flexible 1/16" acrylic, but you can make it from a student's plastic report cover (for those who date to before Word and emailing a report). The outer dimensions are 4.5 x 3.75" and the inner rectangle is 2 3/4 x 1 13/16", which gives a perfect 3:2 ratio for a full frame camera. The distance from your nose will depict these mm views:
25" = 400mm (my arm's length)
6" = 100mm and 105mm
4" = 70mm
3" = 50mm
1" = 35mm
right at the tip of the nose = 24mm
pressing on the nose = 16mm
There is a $30 phone app available which will do something similar, but takes several minutes to start the phone, then the app, set the focal length, etc. and then you still see the whole screen image with a dotted line around the rectangle of your mm choice. It's hard to mentally exclude the image elements surrounding that rectangle.
This is a 1-2-3 solution that takes 10 seconds to see the frame at any focal length, one after the other. The 3/4 to 1" surrounding black material forms an excellent frame, giving a real-life impression of a photo at that focal distance. A number of photo sites recommend this viewfinder, but I found none ready-made.
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