When considering the purchase of a rifle scope it’s important to know what you’re investing in and how it affects your shooting. An often misunderstood concept when choosing a rifle scope is the difference between first focal plane (also called a front focal plane) and second (or rear) focal plane scope. There are pros and cons to each but what does first and second even mean?
FIRST FOCAL PLANE (FFP)
First, or Front, Focal Plane scopes have the reticle installed toward the front of the erector tube, the part of the scope that houses the erector lens and responds to adjustments in windage and elevation via the knobs on the top and side of the scope. This is significant because as the shooter adjusts the magnification of the scope the zoom lenses inside the erector tube also move toward or away from the reticle resulting in the reticle “growing and shrinking” as the adjustment is made. The crosshairs remaining a constant size in relation to the target.
Note the difference in size of the reticle from low to high power. The size in relation to the target, however, stays the same.
FFP Scopes have the disadvantage of being expensive and in certain situations the reticle can actually obscure a target that may be particularly far down range. The constant reticle calibration is however a big advantage that many shooters find to be worth the extra cash. Especially for competitive shooters who may face a number of different ranges in a given match.
SECOND FOCAL PLANE (SFP)
Second, or Rear Focal Plane scopes have the reticle installed toward the back of the erector tube. As such it is not subject to the perceived resizing when adjusting the magnification from the movement of the erector lenses. The reticle stays constant in relation to the shooters eye instead of the target.
In this example the reticle stays the same size relative to the shooters eye as they switch from low to high power.
Although cheaper to produce and purchase, a disadvantage of a SFP is that the reticle is only in correct calibration at one specific power. These scopes are best used when you’re shooting at known distances.
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