That is basically correct. A virtual image, however, can exist at any position. The reticle or red dot is a virtual image. It has all the characteristics of a real image, like parallax and focus. If you focus your eyes on the distant target, the red dot or reticle will also be in focus, even though the physical reticle or dot is very close. Better scopes have a parallax adjustment which can place the effective position of the crosshairs anywhere from a few tens of yards out to infinity. When no adjustment is present, the parallax free distance is set by the manufacturer; usually 100 yds for a rifle scope and 50 for pistol. I believe different parallax free distances are available for some scopes special order. An interesting thing about this is that the reticle or dot can actually be behind the target! Looking at a 200 yd target through a typical scope, the reticle is in front of the target (at 100 yds). Parallax is as you might expect for two objects at 100 and 200 yds respectively. If you move your head to the right, the reticle will shift to the left relative to the target. If you look at a target at 50 yds, the reticle is still at 100 yds. And the parallax is again as you might expect for objects in this configuration. Moving your head to the right will cause the reticle to also shift to the right. This is easier to understand if you imagine that the target is transparent and can be placed either in front of or behind the reticle. In spite of it's physical location, the reticle behaves as if it were at 100 yds.