When it comes to focal plane and scope systems there is no wrong, or bad, choice; there are just choices based on use. The best choice, and reticle, largely comes down to what you prefer, though stronger use cases can be made for either one depending on the situation. This article will briefly walk you though the major differences and discuss where each might have advantages in terms of application.
The fundamental difference is that with a first focal plane scope (FFP) the reticle grows as the magnification increases. On a second focal plane scope (SFP) the reticle will always be the same size.
Pictured above is the Vortex PST Gen2 5-25x50, a great FFP option.
FFP
In a FFP, because the reticle grows and shrinks with the magnification, so does the size of the reticle. Below are two examples of a FFP on 10x, the first is the Meopta 3-18x50 and the second is the Burris Signature HD 5-25x50.
When designing reticles for FFP scopes, manufacturers have to strike a balance between what is usable at low, and high, magnifications. In the first example (Meopta, left) on 10x in the sight picture it is easy to read the subtensions (distance indicators under the main crosshairs) on 10x. This reticle is very legible at all magnification settings from 3 to 18. You want the reticle to be large enough to use on the lowest power, but also such that it is still useful on the highest. Again, neither one of these is necessarily better, it is more accurate to say they are each "better" at doing different things.
On the right is the reticle from a scope (Burris Signature HD) that magnifies from 5-25x set to 10x. Notice how the stadia lines are more difficult to pick up? Again, the designers are tying to strike the balance between usability at high and low magnifications. In this case, the scope has 7 more magnification settings on the high side so, to be useable on high settings, the reticle has to be smaller on lower settings. This can create challenges when it comes to effectively using the crosshairs on lower settings (maybe 5-8x in this case).
When selecting a FFP scope it is helpful to identify your most common use, the magnification you will need to do this, then select a magnification range and reticle that is well suited to the task. If all of your shooting is at targets at long distances, then the usability of a reticle on the lowest power probably matters a lot less than if you are using a scope in a hunting application where shots are of varying distances and can be at close range. Regardless of magnification and reticle selection, if the scope is FFP and has stadia lines, the measurements those lines represent remain constant at all magnification settings.
SFP
In a second focal plane scope (SFP) the crosshairs always stay the same size. These scopes come with the same wide array of reticle choices as the FFP scopes but there two important distinctions. The first is that because the reticle is always the same size, it is easier to see the crosshairs on target on lower magnifications because they don't "shrink." This is particularly useful when hunting as crosshairs that are easy to see make it easier to get on target quickly. The drawback, however, is that because these crosshairs don't scale with magnification, the posts and crosshairs can appear extra thick on high magnification which can partially obscure the target. For example, my LPVO (PST Gen 2 1-6) has crosshairs thick enough that on 6x at 100 yards they completely cover the bullseye on the target making it hard to see. The other consideration is that if you have subtensions on the scope they are only accurate as advertise on the highest magnification. As an example, if you had 3 stadia lines representing 2,4, and 6 MOA etched on your scope reticle, and your scope is a 4-16x, those 2,4,6 values are only good at 16x. The relationship between power and stadia is that if you halve the power, you double the values. So, on 8x your stadia values become 4,6, and 12. That has a couple of implications: 1. you need to memorize these values or do the math in your head on the fly and 2. At lower magnifications your stadia lines will have such high MOA values they will probably not be very useful.
Conclusion and What I Shoot
I hope this was a helpful article and you learned something about the fundamental differences between FFP and SFP scopes. For me, when I am doing serious target shooting I want a FFP with a Christmas tree reticle (I like the Burris XTR II 5-25 with the SCR and the Vortex PST gen 2 5-25) with exposed turrets. For distance hunting (I like the 6.5cm round) I like a FFP reticle with subtensions, capped wind, and a locking exposed elevation turret (Meopta 3-18 x 50). For hunting where I know most shots are 300 yards and in (my .243), I use a SFP and zero to MPBR and only dial if I exceed that distance. Using a dead hold, I like a duplex reticle with capped windage and elevation (Meopta 3-18 x 56). For hunting at 300 yards and in, I again go SFP with a heavier bullet (my 30 30) I use a duplex with locking elevation and capped wind (Leupold VX3-HD 2.5-8). For a sporting rifle (like an AR platform) I always want to have a true 1x in the package so go with an LPVO (mentioned above). This is a SFP scope with subtensions (the only one I have) and I would probably prefer it FFP, though it is a pretty darn good scope. That's it for now, be safe and have fun.
Comments