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.
Let’s take a look at the evolution of Prism scopes through the years and compare modern options from four well-known brands: Vortex, Swampfox, Primary Arms and Bushnell.
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.
Reticle Design
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.
It’s best used with shotguns and PCCs, being optimized for 100 yards and closer. All other 1x scopes are focused at 100 yards.
User Interface
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.
Batteries
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.
Lens Covers
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.
Recoil Resistance
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.
Conclusion
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.
Good comparisons although you said that all of these optics came with lens covers. Not so with the Lil P.
I’m going to choose my words carefully here.
Nonetheless–rangefinding and bullet drop compensating reticles have ABSOLUTELY NO PLACE in a non-magnifying sight. A non-magnifying sight like these is for fast work at close quarters. Given that an M16A2 rifle’s iron sight battlesight zero is three hundred meters, and given that the prismatic optical sights at least theoretically eliminate all the difficulty of aligning and centering iron sights to make the shot, a simple 2 MOA dot in the center is all the reticle anybody should need to put metal on target on demand out to a quarter mile. And if you are lobbing bullets into the air to try to drop them on target further away, a non-magnifying sight is not the optimum tool for the job.
Give me a 17.5 MRAD diameter circle with a half-mil circular dot in the center and I’m happy. If a standing man fills the circle bottom to top he’s 100 meters out. If a standing man fills half the circle, from the center dot to the top edge, he’s 200 meters out. It’s conceivable that a pistol caliber carbine user might find that a useful feature. Otherwise, give me that two minute dot and please refrain from distracting me with rangefinders, lead indicators, racing stripes, good luck charms, and fuzzy dice. If I’m using a low power variable optic instead of a nonmagnifying prismatic, keep everything the same and make sure that 2 MOA dot is 2 MOA at 1x, shrinking proportionally as magnification goes up.
If y’all can’t restrict yourself to a dot, then give me a post reticle, square on top, 1/2 mil wide at the tip, tapered out to 1 mil wide at the bottom edge of the field of view. Simple, simple, simple. No confusing profusion of multiple concentric circles. No chevrons. No rangefinders. No lead indicators. No bullet drop compensators. If I am using a lightweight carbine like an M4 for close work I want no distractions other than “put reticle here and press trigger.”
Actually I will say that things like the mil dot reticle have their place–in a 20x scope bolted to a precision bolt gun for offensive work, where the operator has the leisure of estimating wind speed and counting mils for deflection to compensate before breaking the shot. But on a lightweight carbine for home defense that is unlikely to be used at distances past 50 meters? Simple is fast and fast wins the fight.
The optic’s field of view is irrelevant when shooting with two eyes open;
http://ultimak.com/UnderstandingE-Sights.htm#fie
“Cumulative” or “Composite” Field of View is always around 180 degrees.
That the manufacturers keep publishing the same specs as for a telescope demonstrates that they still don’t quite get it. You’d be concerned about FOV in a 1x, or any BAC, optic only if you were missing and eye.
If Trijicon can illuminate an etched reticle in their BAC models without an LED, using fiber optics and even tritium, obviously the challenge isn’t insurmountable.
Good article. I’ve been debating picking a 1X Prism vs a 1-6 Variable for my AR in 5.56. For what I’m looking for this answered many of the questions I had. Thank you.
Will C.T.D be selling scope mounts used when firing the gun sideways?
What is the most effective scope used by
A Russian man 91.30
B Mauser K98
C Enfield MKI
D. FRENCH Libel
Young people can have astigmatism too. Ive had it in my right eye since i was little.
Just sayin…