Options for making good shots on the edges of day.
It's common to encounter big game as light diminishes. Illuminated reticles and red dot sights can be a big help.
Riflescope lenses don't really "gather" light. They can only deliver incident light. Still, riflescopes can extend shooting hours by concentrating incident rays into a shaft of light the diameter of your scope's exit pupil. When the exit pupil is at least as big as your eye's pupil, you get maximum benefit.
In truly dark conditions, even the biggest, brightest lenses leave you with a dim sight picture. Eventually you lose not only the target image but the reticle as well. Which you lose first depends on the nature of the target and the design of the reticle.
Many years ago I found myself face to face with a bull elk in the last minutes of legal shooting time. When I raised my rifle, the Lyman Alaskan showed me only the faint image of the elk. My three-minute dot reticle had disappeared. I tried looking off-center in the scope. No luck. Then I spied a spot of ivory-colored grass. Centering that thatch, I could faintly see the tiny gray dot. Gluing my eye to it, I swung it into the black mane and tawny ribs and fired.
There's an easier way. Electronic or illuminated reticles show up even when night has fallen. Battery-powered, most are adjustable for brightness. A rheostat allows you to turn down the brightness under dark conditions, and up when the standard black reticle has just begun to fade.
You're smart to use the lowest setting practical. Too much brilliance and your reticle appears bigger or thicker than necessary, hiding your target. It also loses its clean-edged profile and prompts your eye's pupil to contract so you receive less light around the reticle and consequently lose track of your target.
Red dot sights offer a similar view and controls but are of different construction. Aimpoint built the first red dot sight in 1975. On current models, a compound front lens corrects for parallax, bringing the dot to your eye in a line parallel with the sight's optical axis. With an Aimpoint, you hit where you see the dot, even when your eye is off-axis and the dot appears off-center in the field.
Aimpoint sights with no magnification boast unlimited eye relief, so you can aim fast with both eyes open. The company's latest circuitry reduces power demand, boosting battery life to 50,000 hours with the brightness set at seven.
I've shot a couple of moose with an Aimpoint sight. Probably neither would have dropped had I been using iron sights or a conventional scope. The first animal, a bull, was in dark timber at 90 yards, all but invisible with the naked eye. But the Aimpoint dot found a sliver of shoulder.
The second animal, a cow, galloped at twilight through heavy rain in shaded forest. Iron sights or a black reticle would have been swallowed by the gloom, but with Aimpoint's dot at a low setting, I made the fast shot easily.
Trijicon offers the AccuPoint line--1.25-4x24, 3-9x40 and 2.5-10x56 models--with red or yellow pyramid-on-post reticles that are powered by a combination of tritium and fiber optics. Brightness can be adjusted by turning a ring on the scope, and best of all this system requires no batteries. Trijicon's new TriPower uses similar technology but adds a battery backup.
I used an AccuPoint recently on an elk hunt. Sneaking into bedding cover with an 1895 Marlin, I slipped into a herd, looking for antlers. A bull slipped from behind a deadfall thick enough to claim my first bullet, and I missed the second shot but landed the third perfectly just as the elk reached heavier cover.
Against the mottled woods, that bright yellow delta shone clearly and made fast follow-ups possible.
On scopes of high magnification, I forego lighted reticles. Here's why. Powerful optics are best suited to long shooting in open places under good light. They also suggest still targets, deliberate shooting and a requisite for precision, and if a shot's that far and it's so dark I can't see a black reticle, I don't want to take the shot.
Also, I like slim, simple, lightweight sights, and though some makers have replaced those ugly battery warts with cleverly tucked compartments in the turret, I'd rather limit my battery indulgence to red dot sights.