The Three Foot Rule
- Thread starter JazzDad
- Start date
santafewillie
Same Ol' Buzzard
Allen McClelland is the first person that I read that used this phrase, but I don't know if it originated with him. He was in HO.
In 1:1 you're probably too close. In Z scale I cannot see it at three feet.
In 1:1 you're probably too close. In Z scale I cannot see it at three feet.
It then becomes the "cross-eyed" rule.
Good to Know!
Selector
Well-Known Member
It's a personal choice over the amount of detail you'd like to see, or the realism. As you must know, some models offer more details, and of course they cost that much more. Others have details added by someone who can do it and who appreciates the increased realism. But, there comes a point where there are diminishing returns.
If one likes model photography, as I do, one must either suspend disbelief when he sees an HO model in an otherwise good image, or he needs to increase realism by adding details until the scene 'pops'. For Z scale, one would need to have one's eyes about one foot away, and the subject would need good lighting, to see added details such as number boards, builder's plates, rivets, etc.
The human eye's ability to see details is a function of the diameter of the iris. In optical systems, of which the eye is one, the diameter of the main objective or iris sets the limit of how fine a separation of two small items set very close to one another can be detected. For example, the human eye can often tell that the North Star, or Polaris, can be seen as two objects. What isn't seen until one uses a much larger iris or objective lens, such as on binoculars, is that one of the pair is also binary in nature. So, a total of three stars comprises the North Star!
To make this perhaps more understandable, suppose you typed two periods very close to one another on an otherwise blank page. You could back up until they appear to be one elongated period, and eventually you would see only a dot if you backed up even more. Now, take a small pair of opera glasses, maybe with 4X magnification and 20 mm objective lenses up front, and you'd easily see the pair once more. You've magnified the image, yes, but you've also greatly widened the 'aperture' of your optical system with those twin 20mm objective lenses.
So, proximity to the object, separation, incident light, and the distance across the main aperture of the optical system all play a part in showing details.
Stand 3 feet away from the layout.
I like Crandell's explanation best.
If with my spectacles on, I roll my chair 6' away from my monitor, I could read it without much difficulty. If I rolled it back another 3', I couldn't. If I rolled my chair back in close up to the desk and took them off, I could read it then as well. If I sat where I normally sit, with them still off, couldn't read a word.
So I guess the verdict is, if I want to read my monitor comfortably, I should position my chair where I normally do, AND wear my spectacles.
If with my spectacles on, I roll my chair 6' away from my monitor, I could read it without much difficulty. If I rolled it back another 3', I couldn't. If I rolled my chair back in close up to the desk and took them off, I could read it then as well. If I sat where I normally sit, with them still off, couldn't read a word.
So I guess the verdict is, if I want to read my monitor comfortably, I should position my chair where I normally do, AND wear my spectacles.
Or.... You could supply the other types of glasses and keep them copiously filled and no-one would be seeing anything too clearly very quickly. And all would have 3 feet.
