The DI Optical FC1 is the 3rd rifle optics that I have reviewed from the South Korean optic manufacturer. I have previously reviewed the DI Optical RV2 for Guns&Tech and the EG1 for Firearms News in print. The FC1 in its name is short for “Falcon 1”, and the FC1 is the commercial version of the DI Optical DCL23 military sight. Due the the South Korean arms export law, the DCL23 is restricted to sales to military and law enforcement only. DI Optical USA told me that all of the commercial sights are build to the same spec as their military sights, the renaming and minor design changes are mostly to separating them from the military models.
At the first look, the FC1 looks like the miniature version of the bigger EG1 since both are based on DI Optical’s prism red-dot design. It’s a technology that uses a single prism instead of multiple lens as the optical element in the design. The prism is completely filled the space between the front and rear lens. The advantage is that it offers better sealing from the environment, and the glass prism reinforces the billet aluminum sight housing to making it even stronger.
Not to be confuse with the magnified prism sight like the Trijicon ACOG or even the true 1x prism sight like the Vortex Spitfire AR 1X, the prism in the DI Optical FC1 sight is non-magnified with unlimited eye-relieve and has no eyebox restriction. The DI Optical FC1 a true red-dot sight.
Small and relatively lightweight, the DI Optical is in the same class as the popular Aimpoint Micro. Two of the big improvement the DI Optical FC1 has over its military model are the build-in height adjustable modular mount base, and its smaller digital illumination control that uses just a single button instead of the analog rotary dial found on the DCL23 military version.
The DI Optical FC1’s field of view (FOV) is huge for such a small sight. To me eyes, its square shaped ocular window feels almost 1/3 larger than the typical 20mm circular lens used on the Aimpoint Micro T1, T2 and its clones. I would say the DI Optical FC1 has a FOV as large as that of the Trijicon MRO with it’s 25mm objective size. Fortunately, the DI Optical sight has none of the Trijicon’s various optical anomalies.
Also see in the above picture is the bright red reflection of the dot illumination. The DI Optical FC1’s 2-MOA dot illumination is more than bright enough to use with a desert background on a sunny summer day. As a matter of fact, I found the DI Optical FC1’s top illumination level (#7 daylight setting) to be too bright for normal use and it produces a halo effect from the LED illumination. Noted that unlike the full size EG1 model, the illumination component on the FC1 is moved to the right side. Which I can assume that the relocation was for lowering the overall height of the FC1.
With the mount spacer installed, the DI Optical FC1 offers a lower 1/3 co-witness with the standard AR15/10 sight height. Take out that spacer, it’s too low for absolute co-witness on an AR15, however, it’s the perfect sight height for using the FC1 on the FN SCAR, the various Sig rifles, or Korea’s K1 or K2 rifles.
Like the full size EG1 model, the FC1 comes with a simple knurled thumb screw mount base. For a QD mounting option, the stock base could be replace with a ARMS #17 QD mount.
The DI Optical FC1 on my DDI AK. I removed the thick spacer in the FC1’s mount base and lowed the sight height by a bit. Although it’s usable, the DI Optical sight is a bit tall for use with straight AK stock, such as this Circle 10 AK Triangle Stock, without a cheek riser.
The DI Optical FC1 is mounted on the new Midwest Industries Gen 2 Mini Picatinny rail AK side mount. The field of view from the FC1 is awesome on the AK as with using it on the AR15.
DI Optical FC1 Specification:
Objective: 21mm x 15mm multi-coated prism
Body: CNC 6061-T6 Aircraft grade aluminum construction w/ Hard anodized
Size: 1.89-in (L) x 1.69-in (W) x 1.69-in (H)
Weight: 6 oz.
Reticle: 2 MOA dot
Adjustment: 40-clicks, 1 MOA per click
Illumination: 14 levels, 7 day and 7 NV settings
Power: 1x CR2032 size lithium battery
Battery Life: 1,000 hours at high, 3,000 hours at middle setting, 5,000 hours at low and NV setting
Water Submersible: 10 ft