Up to just recently, you and I have heard little about this. Why? Because the choice in hunting scopes has always been made by the manufacturer as second focal plane in the rear of the scope after the erector lens’ where the reticle (crosshairs) does not magnify or shrink with the image as you turn the magnification dial, only the target enlarges.

See Images and website below by looking for images of first vs second focal plane.

http://www.bing.com/images

Second Focal Plane works to the advantage of many hunters that are shooting small targets such as distant prairie dogs or exacting long range bullseyes at known distances in competition like F- Class because the crosshairs do not thicken and cover the bullseye center.

The downside is that the reticle crosshair hash marks in Mils or MOA lose their true meaning unless set at a specific power setting but for F-Class or game that has been ranged with a rangefinder, who cares, we know the distance.

If the reticle (crosshair) is put in the front of the scope ahead of the erector magnification lens system, called first or front focal plane, the lens will magnify/enlarge the crosshairs as the magnification dial is turned and the hash marks are accurate at any power in Mils or MOA. The benefit in holdover on a target with unknown distances can be seen in that way as your mil/MOA marks are accurate like in a moving shooter situation and unknown distances such as tactical situations. Below is a great discussion by Leupold at GunTalk.TV.

Hope that helps! From a scenario such as a long range hunter with a laser rangefinder or F- Class then shooting Second Focal Plane makes sense. If you shoot tactical and unknown distances and need the hash-mark to be accurate and don’t care if your crosshair gets larger then shoot First Focal Plane.

Good Shooting!