AR15, thanks for your commenst and explanations. But there's still something about it that doesn't seem right.
It's physically impossible (optical laws of refraction of light rays as they travel through one medium to another) for a rifle scope to have the target image focused exactly on the reticule and the aiming eye seeing the reticule in sharp focus and not have both target image and reticule as sharp as can be as seen by the human eye.
For a given focal length of the combined lenses in front of the reticule, there's only one finite point where a target at a given range will focus sharply. Same for the eyepiece and the human eye; there's only one finite point in front of the eyepiece lens that the human eye can naturally focus on.
If you're referring to the side adjustment (focus or parallax, whatever one chooses to name it) being set to a range but the target image from that range isn't in sharp focus, then I understand what you're saying.
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master