Flag Lock 101: How to lock, and Why It Matters

Flag Locking or Pin Seeking is the feature that separates a golf rangefinder from a hunting scope. It helps the laser pick out the flagstick instead of the trees behind it. Once you know how it works, you can get a clean lock on the first try and, with a connected rangefinder, see exactly where that pin sits on the green.

How pin seeking works

A laser rangefinder fires short pulses of light and times how long they take to bounce back. When you aim at a flag, the beam often hits several things: the flagstick, the green behind it, and a tree line farther back.

Pin seeking mode prioritizes the closest target it detects. Because the flag is almost always the nearest object in your sight line, the rangefinder reports the flag distance and ignores the background. When it locks, the display confirms it so you know which reading you got.

Why you get the wrong number

Most bad readings come from one of three things:

• Shaky hands. The crosshair drifts off the stick and catches the trees behind it.
• Something in front. A mound, bunker lip, or overhanging branch sits closer than the flag and gets locked first.
• Too far away. At long range, the flagstick is a thin target and fewer pulses hit it.

The technique for a clean lock

1. Brace yourself. Tuck your elbows into your chest, or rest your forearm on the cart. Steady hands do more than any setting.
2. Aim at the flag (the cloth part or the stick). Put the crosshair on the middle of the flag, where it stands clear of the green.
3. Hold and sweep. Press and hold the button, then move slowly across the flag. Pin seeking will grab the closest object it passes.
4. Wait for the lock confirmation. Release once the display shows the lock and vibrates twice on the Swingman.
5. Double-check on blind or long shots. A second reading takes a few seconds and catches the occasional miss. 

Check your lock against the green

Here is a trick only a connected rangefinder can do. On a Swingman paired with TheGrint (annual Pro membership required for green data), the lens shows Front, Center, and Back distances alongside your laser reading.

Use them as a sanity check. If the green runs from 140 to 165 yards and your laser says 182, you locked onto the trees, not the flag. Shoot it again.

Read where the pin sits, front to back

Once you lock the flag, the Swingman lens shows the pin's position on the green, front to back. This turns a single yardage into a real picture of the shot.

Why it matters: green depth can be bigger than you think. A 25-yard-deep green is a two-club difference from front to back for most players. Knowing the pin is tucked 4 yards on, versus sitting in the middle, changes your target.

• Front pin: the margin short is small. Play to the center and take your two-putt. Or if the green is guarded by bunkers, maybe a layup is the best shot to avoid bunker penalties
• Middle pin: the best chance to attack. Club for the flag number.
• Back pin: going long is often the bigger danger. Aim at the middle and putt uphill. If you are uncomfortable with lofted shots, go for the front of the green and roll it back (as long as theres a backstop). 

Frequently asked questions

What is pin seeking on a rangefinder? A mode that prioritizes the closest target in the beam, so you get the flag distance instead of the background.

How do I know the rangefinder locked the flag and not the trees? Wait for the lock confirmation. On a connected Swingman, also check that your reading falls between the Front and Back green distances.

Does the Swingman show where the pin is on the green? Yes. After you laser the flag, the lens shows the pin's relative position front to back. This feature requires an annual TheGrint Pro membership.