First Focal Plane and Second Focal Plane Scopes [Complete Guide]
9/17/2018Primary Arms Staff10/2/2020 9:01 amwww.primaryarms.com
A quality rifle scope is essential to optimizing the performance of your modern sporting rifle, hunting rifle, or favorite .22 caliber plinker. Find the perfect scope for you, your rifle, and your shooting needs and you will be pleasantly surprised at how much faster, more accurate, and more consistent you are with your firearm. You’ll love to shoot it more too. So a little education to get in moving the right direction when choosing a scope is in order.
Today we are talking First Focal Plane (FFP) and Second Focal Plane (SFP) rifle scope configurations. How each configuration works makes a big impact on what kind of shooting application the scope is best suited for. If you do not understand the differences between these configurations and how to best employ them to work in your favor, you run the risk of having a rifle that is best suited for one job and a scope that is best suited for something else. That’s a real quick way to get frustrated on the range or in the field. So we are going to run down everything you need to know about FFP and SFP scopes in this first installment of Scope University. You’re probably going to want to take notes.
What’s The Difference?
The easiest way to tell whether any variable zoom optic is first focal plane or second focal plane is to simply look through it while turning the magnification ring to change the scope’s power setting. If the reticle appears to grow as you scale through the magnification settings, it’s a first focal plane scope. If the reticle looks the same regardless of magnification, it is a second focal plane scope. Now that we know what we’re looking at, let’s look at these differences in a little more detail…
In FFP scopes, the reticle’s size appears to grow and shrink as you scale up and down in magnification, you can get the reticle out of the way, so to speak, and see more of the target with an unobstructed field of view at lower powers. When you want to take a very precise shot, and scale up the reticle, advanced features and precision points of aim become larger on the reticle, and easier to use. Because the reticle’s size stays the same relative to the target at any magnification, those advanced features like BDC and ranging are always mathematically accurate and can be utilized at any magnification setting.
In SFP riflescopes, as you scale from low magnification to high magnification, the target will get larger and larger filling up more of your field of view. However, the reticle will always appear the same size, so these reticles are usually designed with that in mind. Very fine crosshairs or points of aim must be used so as not to obstruct the view of the target at high power. At low power, it can become difficult to put such fine crosshairs accurately onto a smaller target. For an SFP scope, additional reticle features like bullet drop compensation (BDC) or ranging will only be true at one magnification setting.
Get The Right Tool For The Job
Second focal plane scopes are most often found in low-power variable zoom optics. First focal plane is usually a more popular option in precision optics with their maximum magnification higher than 10x power. There are many exceptions to this, but it is still useful to consider FFP and SFP applications in each type of optic separately. Let’s take a closer look.
Low Power Variable Optics: 1-4x, 1-6x, 1-8x
Low power variable optics favor quick target acquisition over long-range precision. Intended for use at close to medium ranges, most have large and simple reticles that catch the eye quickly. There is not much of an advantage to the FFP configuration when using a simple crosshair that does not have advanced features, so manufacturers generally steer clear of spending the extra money that it takes to manufacture FFP scopes when producing low power variable optics. We will talk about why they’re more expensive later.
Many shooters do appreciate second focal plane designs because the sight picture is always consistent. However the most significant disadvantage of SFP scopes when compared to FFP is that any advanced features like bullet drop compensation and ranging can only be calibrated to be accurate at one magnification setting. With very few exceptions, BDC and ranging in SFP scopes are calibrated to be accurate at the highest magnification setting. It makes sense; the highest power magnification is likely where you’ll be taking a long-range shot anyway, so that is where those features are most useful. However, if you have ever lost the opportunity to take a good shot because that trophy 10-point ducked under some brush while you were fiddling with your optic, you can understand the potential upsides of being able to range estimate and account for bullet drop at any magnification.
The FFP design enjoys reticle calibrations that are true at all magnifications. Ranging is always true, and a 400-yard shot using the 400-yard BDC mark will always hit your target at any magnification setting. However, in low power scopes, sometimes it isn’t so easy to use those features at the lowest powers. If the reticle is designed poorly and the features aren’t prominent enough, you won’t be able to see them at anything less than full power anyway. If they’re too prominent at lower power, they’ll be impossibly obtrusive at the higher magnification ranges. Many shooters say they’d never take a shot at distance using anything less than full power magnification. Why sacrifice any greater accuracy potential that comes with a more magnified sight picture?
New Low Power Paradigm: ACSS Raptor
But that’s not to say FFP low power variable scopes are always a bad choice. A well designed FFP scope and reticle can take full advantage of the scope’s flexibility to give you truly optimal performance in a number of applications. A perfect example is the Primary Arms 1-6x24 FFP scope with our ACSS Raptor reticle. The Raptor has advanced features for precision shooting at medium to long range. The patented ACSS Chevron tip does not obscure the view of the target, and two forms of ranging features are built into the reticle, allowing you to quickly estimate your distance to targets as far away as 600 yards. Wind holds for 5 and 10 mph and moving target leads are present as well – it’s packed with features.
What makes the Raptor unique – and purpose-built for a FFP configuration – is that all the advanced features of the reticle are contained inside the familiar ACSS CQB Horseshoe. As you shrink the reticle down to 1X power, the horseshoe begins to function more like a red dot sight or holographic reflex sight. It is a small, easy to acquire point of aim, and the Raptor’s true 1X magnification makes it possible to shoot with both eyes open, just like using a red dot sight or similar optic. Medium range shots can be taken accurately and quickly with the Raptor when deployed at medium magnification by quickly centering the horseshoe on your target and then shifting to the chevron for precision. At the highest magnifications, the 11 illumination settings make it easy to dial up a perfect sight picture that contrasts on your target but won’t block your field of view. At the low settings, the illumination gives a red-dot-type sight picture. This is one example of a well-designed FFP low power optic that is built to take advantage of the FFP’s flexibility. You’ve got to be an informed buyer to get the most out of your scope.
High Magnification Precision Optics: 10x Maximum Power and Beyond
Precision rifle shooting at long range involves a different set of challenges that must be addressed by scope manufacturers. Of course, it is important to remember that one inevitable challenge is that the higher magnification capability a scope has, the larger and heavier it will be. A first focal plane scope’s ability to keep the reticle in true calibration at all magnifications becomes supremely valuable as the number of available magnification settings and overall magnification power increases. For instance, a Primary Arms 6-30x56 Platinum scope features 6x magnification as the lowest magnification setting. Many low power variable optics top out at 6x power. It’s not hard to see how the challenges change when the capabilities of the scopes themselves are so different. In these high-power scopes, the reticle’s advanced features are useable throughout the entirety of the magnification range, and attention to precision at every power is important. Since FFP reticles remain properly calibrated and accurate at all magnifications, long range shooters are able to use them at any magnification setting they wish in order to best find, follow, and engage targets. Because of that flexibility, FFP scopes are unmatched in their utility for precision rifle competition, long range hunting, and precision military or law enforcement applications.
One exception may be benchrest shooting, when small group size is the goal and targets are at known distances – 600 to 1,000 yards. SFP scopes can be more useful for this niche shooting application because all shooting is done at maximum magnification on identified targets, and a supremely thin crosshair reticle is able to provide the most precise point of aim. Because ranging is unnecessary, the reticle is simple, and adjustments are made using very fine 1/8 MOA clicks instead of holdovers. In the benchrest application, your scope will be so purpose-built that SFP and FFP is almost irrelevant. SFP is likely your winner.
Construction Zone Ahead
Is there a difference between how first focal plane and second focal plane scopes are constructed? It is impossible to tell by just looking at the outside of the scope. For example, Primary Arms offers 1-6x24mm scopes in both focal plane configurations that look practically identical. The FFP versions are eight-tenths of an inch longer. That is the only difference – on the outside. The real difference is in the internal location of the reticle. And since this is Scope University, let’s discuss how these advanced reticles themselves are produced.
How the reticle is made
Today’s precision reticles are made using a variety of advanced processes. One of the most advanced is to chemically etch the reticle into a piece of glass, which is most widely used in applications where small and heavily detailed reticles are required. This piece glass has absolutely zero effect on magnification. Its only purpose is to contain the reticle. Carefully-applied chemicals eat away at the surface of the glass to form the shape of the reticle, and the resulting area is filled up with a special chemical paint to provide contrast. With the etched glass carefully prepared and cleaned, a second piece of glass is permanently affixed overtop of it, protecting the reticle’s etching. Why is it important to discuss this part of the scope-making process in a discussion about first focal plane versus second focal plane construction? Because the reticle’s location inside the scope is the determining factor that differentiates FFP and SFP configuration.
Location, location, location
SFP scopes locate the reticle lens at the ocular end of the scope. That is the part of the scope you look through. Here, the lens itself is the last thing the light passes through before hitting the eyepiece and then your eye, forming an image. When windage and elevation are adjusted, the adjustment knobs push on the objective end of the internal erector tube containing the magnification lenses, opposite of the shooter. Because the reticle is closer to your eye, the adjustments being made are really only a perception of where the reticle is looking within the wider field of view of the objective lens.
The first focal plane design places the reticle lens at the end of the erector tube, underneath the adjustment knobs. When windage and elevation are adjusted, the adjustment knobs still push on the front end of the erector tube like they do in a SFP scope. The difference is, this time it’s moving the reticle glass too. When you turn your scope’s power ring to increase magnification, the magnification lenses inside the erector slide forward, towards the reticle doublet and the objective lens. Turning in the opposite direction slides the magnifications lenses to the rear, closer to your eye and the ocular lens. This is what makes the reticle appear to grow and shrink as you scale up and down. The reticle is not physically moving within the scope, but the magnification lenses – and thus your eyes – are perceiving it in the same way as they are perceiving the target you are aiming at. Because both the target and the reticle doublet are essentially downrange in relation to the magnification lenses, both appear to grow and shrink as you adjust magnification.
More Money, More OptionsIf the reticle lens location is the only difference in configuration, why are first focal plane scopes generally more expensive than second focal plane scopes? Some folks claim that FFP scopes are more fragile and therefore must be made more durable with more expensive materials. Or perhaps they have extra parts or additional lenses inside that add manufacturing expense. That’s not the case.
The fact is, because of where the first focal plane reticle is located inside the light path of the optical system in a first focal plane scope, it must be etched much smaller than a second focal plane reticle. Think about how much an image grows when you scale up a riflescope. The reticle in a FFP scope has to start off small enough to account for the magnification range. And that can mean they are impossibly small, and incredibly difficult to manufacture. The rate at which FFP reticles have to be scrapped because of production issues is far higher than the rate of SFP reticles that don’t pass quality control. The tolerances for FFP reticles are much more strict as well.
Here’s an example:
Imagine two reticle lenses have the same tiny manufacturing flaw in them; an unwanted speck of debris on the lens. The speck might be too small for the eye to see in a 1-6x24 SFP scope because the reticle (and the speck) will always appear to be the same size at all magnifications. In the equivalent 1-6x24 FFP scope, the tiny speck will be magnified, appearing much larger at the 6x magnification setting. Suddenly a speck too small to notice at 1x will cause the scope to fail its quality control inspection at 6x. High magnification precision FFP scopes magnify any flaw in the reticle lens to such obvious proportions that the scope will never be useable in the field.
For this reason, reticle and scope manufacturer’s “clean room” facilities must be held to higher standards when constructing first focal plane scopes, and the technology used to clean and precisely assemble FFP scope internals must be upgraded significantly. The quality of the glass itself or the multi-coating treatment may also have to be improved for the FFP version of a scope to meet expectations. This brings the total cost of the FFP scopes up compared to the easier-to-manufacture SFP scope design.
The Bottom Line
So, which is better, first focal plane or second focal plane? To sum up:
Second Focal Plane Is Best For:
- Shooters using low power variable scopes with fine reticles
- Shooters with poor eyesight who need a large reticle at all times
- Shooters who want a consistent sight picture at all magnifications
- Shooters looking to maximize performance within a strict budget
- Shooters who will always use maximum magnification for medium to long range shooting
- Shooters participating in benchrest or other highly specialized competition disciplines
First Focal Plane Is Best For:
- Shooters using low power variable scopes with a red-dot style sight picture at 1x
- Shooters who want to range estimate and/or use holdovers extensively rather than counting clicks
- Shooters who want to use reticle features like bullet drop compensation and wind leads at any magnification without doing math
- Shooters with a budget that allows for a slightly more expensive optic
- Shooters who want to maximize flexibly for a variety of shooting situations
- Shooters who want to shoot accurately at medium to long range using multiple magnifications
Armed with your knowledge of the distinct differences between first and second focal plane scopes, you should feel incredibly confident that you will be able to identify your needs and shooting preferences and make an educated decision when selecting a new rifle scope. Each configuration has their areas of excellence and their own limitations to consider, but you now have the knowledge to match these configurations to your specifications and get the most out of your next optic. As always, be safe out there and we will see you on the range.