Is there any real utility to ULF?

[sanking]

Along with this, are there any figures about what resolution the eye can perceive at various viewing distances?

Kirk,

John Williams has a chapter on this in his book, Image Clarity: High Resolution Photography.

He says basically this. And it is based on optimum viewing distance of about ten inches, and is related to studies of the actual fovea of the eye which process light.

1. 5-7 lppm has traditionally been accepted as about as much detail as the eye can appreciate, but that this figure is based on a false premise.

2. Studies which show that the eye can resolve from 40 seconds to one minute of arc suggest that the resolving power of the eye is really in the 15-20 lppm range.

3. Some differences in perceived quality may be seen by persons with very good eyesight in the 20-25 lppm range.

4. Resolution beyond 25 lppm can not be appreciated by the human eye.

Sandy King