Sight-Pin Sizing: 6 things you need to know

Archery sights come in all shapes, sizes and configurations. One of the most common sight features you'll see is fiber-optic pins. There’s a reason for that.The fibers gather light all along their lengths, and that light makes the ends glow. So when you take aim with your bow, you’ve got a small, glowing light that you can paste on the target.Years ago, before fiber-optic sights existed, archers used to dip the ends of their solid, metal pins into bright-colored paint to try to make them easier to see. The tiny plastic fibers work much better.If you look closely at today’s fiber-optic pins, you’ll notice they come in different sizes. And so you might ask yourself, “What size should I have?”Ultimately, it’s a matter of personal preference, but as you make your decision, here are six things you need to know about sight-pin sizes.

1. The most common fiber-optic pin sizes are .010, .019 and .029 inches. That’s 10, 19 and 29 thousandths of an inch. To a lesser extent, you can also find pins in .015, .040, .060 and .125 inches. The lower the number, the smaller the pin.
2. The larger the pin, the more light it transmits. The smaller the pin, the less light it transmits. (That's assuming the fibers for both are the same length. See No. 3 for the effect of length.) So big pins will still glow in low light, where the small pins could go dark. This could be important for bowhunters and 3-D archers, who each might find themselves in dark woods. Older archers, whose eyes maybe aren't as sharp as they used to be, typically can see the .029 pins well in normal light; they can see the .019 pins with the aid of a battery-powered light; and they usually have trouble seeing the .010 pins under any conditions.
3. Generally, the longer the fiber strand, the more light it’s going to absorb. You’ll see sights where the fiber wraps all the way around the scope – sometimes multiple times. All that fiber surface area is catching light, which is transmitted to the end you use to aim. A pin with 2 inches of fiber is gathering comparatively less light to transmit. It’s going to go dark well before the other one. (Take note that a crack in the strand breaks the light transmission. The pin head will only receive light collected between the crack and the head.)
4. Many fiber-optic sight housings allow you to add a battery-powered light to make your pins glow regardless of ambient lighting conditions. Understand that, unless you can control the intensity of the light, it will make the pins seem bigger. So a .019 pin might seem like a .029 when you turn on your battery-powered light.
5. The smaller the pin, the more precise you can be with your aiming. Large pins will cover more of the target than the smaller ones. So where a large pin might completely cover the 10-ring on a target, a smaller one might allow you to aim at spots within that 10 ring. The more precisely you can aim, the more deliberate you can be about where you want to place an arrow.
6. The farther away from your eye that you move the pin, the smaller it’s going to appear. The closer it gets, the bigger it will appear. This is relevant when you consider the length of your sight bar. A .019 sight pin is going to seem smaller on a sight that sits 6 inches beyond the riser, as compared to one that’s 2 inches out.There’s a similar effect as you back up from a target. That target and your desired point of impact are going to shrink in your sight picture as you back up. The size of your pins, however, remains constant. That's why some sights feature pins of varying size. They'll have the largest pins for the closest distances, and then smaller pins for shooting longer distances.