Okay, So the variable viewfinder is for 35mm actually. So at 6x9 with the dimensions mentioned above, what would be the best frame line to set the viewfinder at to get me in the ballpark for this pinhole camera? I have 35, 50, 90, and 135, I can also set it in between each of these
Use the frame lines for a 35mm lens and you have a practically perfect match for your camera. Same angle of view and different format = different focal length. So you need to select which lines to use based on angle of view, not focal length.
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