Prism scopes actually date back to World War I, being common at the time for use with machine guns and sniper rifles.
These optics use Porro prisms like binoculars for bending the light path and creating a focused sight picture (while being much more compact than refractive optics.) They also offered better contrast until the invention of lens coatings.
Prism Scopes History
The unmagnified prismatic scopes appeared in the early 2000s. Their major pluses are the clarity of the etched reticle and the ability to function without a battery, along with the option of using a complex reticle.
Without a curved mirror in the optical array, prismatic options don’t get fuzzy due to astigmatism in older users’ eyes.
The first widely available 1x scope, Leupold 1×14, was expensive and lacked built-in illumination desirable for a sight used with both eyes open. An add-on illumination module added to the cost, and battery life was disappointing.
Not all makers go with complex reticle designs: Vortex Spitfire uses a center dot with two concentric rings around it. Their emphasis is on rapid close-in performance.
Primary Arms Cyclops, while using almost the same optics, employs a more sophisticated DBC reticle to enable range-finding and drop compensation to several hundred yards.
Without magnification, the makers have to find a balance somewhere between features and simplicity to avoid cluttering the field of view. Swampfox Blade, newer design with impressively sharp glass, tried to nail that perfect compromise with the emphasis still on CQB.
Bushnell Lil P uses a simplified variation on the Blade design. While prism scopes have long eye relief, it’s far more restricted than with red dot and holographic sights.
Battery life is also shorter since the LED illuminator has to light up black etched elements.
White reticles was once tried by FN for their P90 sight and found lacking in contrast, so the trade-off between the contrast without illumination and adequate brightness for two-eye aiming remains.
Typical battery life is similar to holographic sights thanks to the use of more efficient LEDs rather than lasers.
Comparing 1x Prism Scopes
Let’s compare the four optics highlighted above by taking a look at features and numbers.
Weight and Dimensions
Weight and dimensions depend a little on which mounts, low or high, are used with Bushnell and Primary Arms models.
- Lil P is the smallest and lightest of the four at around 4.2 oz.
- Cyclops is more than twice the weight at 9.7 oz.
- Vortex Spitfire is similar at 11.2 oz.
- The Blade is the heaviest at just over 13 oz.
Prism scopes, in general, are quite dense. Physical sizes are roughly proportional to the weight.
Field of View
Field of view is remarkably similar, 70-76 feet at 100 yards. Eye relief is also fairly similar, from about 4″ on the full-size scopes to 3. 8″ on Lil P. The difference is in the brightness of the image and the size of the eyebox.
With the smallest lens size, Lil P is less forgiving of decentered eye placement than the Blade, and loses the details earlier at dusk.
With an unmagnified optic, the weak eye can make up for the loss of brightness, but the ability to see the reticle properly from a wider variety of positions can’t be made up like that.
Physical size also provides a more natural view: Lil P has a bit of a tunnel sight picture, while the edges of Blade pretty much disappear from view.
The reticle design shows completely different mindsets. Spitfire’s concentric circles with a small center dot are ideal for straight-stock shotguns like Utas XPR 12 and Fostech Origin 12.
Due to a fixed base, the Spitfire doesn’t work as well for guns with drop stocks. The reticle also works reasonably well for short-range pistol-caliber carbines.
For long-range shooting, the lack of vertical reference and minimal rangefinding features make it suboptimal. By contrast, PA Cyclops uses a very detailed ACSS rangefinding and BDC reticle to 400 or 300 yards, depending on the caliber.
The markings make for a busy sight picture, while actually seeing the target at far out without magnification is a bit uncertain. Blade’s reticle has leveling references and optimizes BDC for close range, from five yards to 200.
Depending on the caliber, the rest of the references work to 300-250 yards, but that’s not the emphasis. The result is a simpler, less-busy reticle that is still fully featured.
Lil P doesn’t even claim BDC function, and the reticle is mostly optimized for distances less than 100 yards. It has a robust vertical reference, but can be overly dense when kit up, obscuring some of the target.
For an optic focused at 50 yards, that’s a reasonable approach. Modular, Lil P works well on AR-15 and other straight-stock rifles—also (without a riser) on drop-stock shotguns and carbines.
It’s best used with shotguns and PCCs, being optimized for 100 yards and closer. All other 1x scopes are focused at 100 yards.
In the user interface, Lil P has 1MOA adjustment clicks and uncovered, though recessed, dials. The other three have 1/2MOA clicks and capped turrets.
Cyclops wins on the illumination design, being the quickest to operate with the rotary dial instead of buttons, and being NV-compatible. The Blade is also NV compatible, but the +/- button interface is slower.
The old model Spitfire has a dial, but it got replaced with buttons in the current version.
All four use 2032 battery that’s easy to swap out. All but Lil P claim 3,000-hour battery life, which seems accurate. Lil P claims slightly longer, possibly due to using a different illumination level for the test.
With 12 levels of brightness available, it can go remarkably dim or full daylight bright. Lil P and Cyclops use red light for the reticle, Spitfire can do red and green in the same unit; Blade can do one or the other.
All of these scopes come with lens covers. Blade also comes with a fairly pointless Killflash grid—the front isn’t reflective, and the included sunshade works well.
All of these scopes are quite recoil-resistant, not surprising given the utter simplicity of the internal optics.
While they might not be ACOG-level tough, they improve on the ACOGs in the much wider field of view and the availability of ocular adjustments to fit the shooter’s eyesight.
As long as your firearm permits receiver-mounted optics (as opposed to forend-mounted) , prism scopes give serious benefits in clarity and ability to work without a battery over red dot and holographic sights.
Do you have a favorite prismatic scope? Let us know your thoughts in the comments below.