How to Use a Monocular: Tips, Focus, and Common Mistakes

Reviewed by the LensSpan Editorial Team

Last Updated: June 2026 | Written by the LensSpan Editorial Team

Learning how to use a monocular properly takes about ten minutes of practice, but most people skip those ten minutes and end up frustrated with blurry images and shaky views. After spending the last several months putting ten different monoculars through their paces on hiking trails, deer stands, and from my back porch in low light, I can tell you the technique matters almost as much as the optic itself.

This guide walks you through exactly how to hold, focus, and get the most out of a monocular, plus the mistakes I personally made so you can skip them.

Quick Picks: Monoculars I Reach For Most

The Problem: Why Monoculars Feel Awkward at First

Here's the thing about monoculars — they're not just half a binocular. The single-eye design changes how your brain processes the image, and if you've only ever used binoculars, your first few minutes with a monocular will feel weirdly disorienting. I remember picking up my first thermal monocular and getting a screaming headache within twenty minutes because I was squinting my non-dominant eye shut the entire time.

That's mistake number one, and I'll get to fixing it below.

The other issue is focus. Monoculars typically have two focus adjustments — the main focus ring and a diopter — and most people only touch one of them. The result is a permanently soft image they blame on the product.

Step-by-Step: How to Use a Monocular Correctly

Step 1: Identify Your Dominant Eye

Before you do anything else, figure out which eye is dominant. Make a triangle with your hands at arm's length, frame a distant object inside it, then close one eye at a time. The eye that keeps the object centered is your dominant eye. Use the monocular with that eye.

I tested this with my non-dominant left eye for a full day during a hike and my detection of distant objects dropped noticeably. Roughly two-thirds of people are right-eye dominant, but assume nothing and check.

Step 2: Keep BOTH Eyes Open

This is the single biggest fix for monocular fatigue. Do not squint your other eye shut. Train yourself to keep both eyes open and let your brain ignore the input from the non-dominant eye.

It feels impossible for the first few minutes. After about a week of practice during my evening porch sessions, it became automatic, and my eye strain dropped to essentially zero.

Step 3: Adjust the Diopter First

The diopter is the small ring (usually near the eyepiece) that compensates for differences between your eyes or for prescription needs. Set this ONCE for your eye, then leave it alone.

To set it: find a stationary object at medium distance, rotate the main focus until the image is sharp, then rotate the diopter until it's even sharper. The 4K Digital Night Vision Monocular has a particularly easy-to-find diopter ring, which is one reason I keep recommending it to beginners. Check Price on Amazon

Step 4: Use the Main Focus Ring for Distance Changes

Once the diopter is dialed in, you only ever touch the main focus ring. Rotate slowly — fast adjustments overshoot and you'll spend twice as long hunting for sharpness.

Step 5: Brace Before You Glass

Hand-holding a monocular at 8x or higher is when shake becomes a real problem. I'll cover steady-hold techniques in the next section, but the short version: brace against something. A tree, your knee, a backpack on a rock — anything.

How to Hold a Monocular Steady

Monocular shake is worse than binocular shake because you only have one hand on the device by default. After a lot of trial and error, here's what actually works:

• Two-hand grip. Wrap your dominant hand around the barrel and cup the objective lens end with your non-dominant hand. This alone cuts visible shake roughly in half.
• Elbows in. Tuck both elbows tight against your ribs to create a triangle of support.
• Brace against your face. Push the eyecup firmly against your brow bone, not just resting against the eye socket.
• Exhale before you focus. Breath movement shows up at high magnification. Take a breath, exhale halfway, then hold.
• Use a monopod for anything over 10x. I bought a cheap trekking pole with a 1/4-20 thread on the handle and it transformed my high-zoom glassing.

Recommended Products for Different Use Cases

> For hunting at dawn/dusk: The TOPDON TS004 hit 11 hours of battery in my testing (matching the spec) and the 13mm lens is wide enough for tracking moving game. Check Price on Amazon > > For tactical or extended nighttime use: The GOYOJO GNG2K with its 60Hz refresh rate and helmet mounting eliminated the motion smear I got from cheaper 30Hz units. Check Price on Amazon > > For serious thermal detection range: The ATN BlazeTrek-325 with its 384x288 sensor picked up a coyote at 380 yards on a 45F evening — well beyond what the budget 256x192 units managed. Check Price on Amazon

Monocular vs Binocular Use: When to Pick Which

I carry both. Here's how I actually decide which one goes in the pack:

• Hiking with weight constraints: Monocular. My Pulsar weighs roughly 9 ounces; my full-size binoculars are over 28 ounces.
• Long glassing sessions (an hour+): Binoculars. Two eyes is genuinely less fatiguing for sustained observation.
• Quick spotting and stowing: Monocular. One-handed deployment is significantly faster.
• Thermal or digital night vision: Almost always monocular. Dual-eyepiece thermal units exist but cost three to five times more.
• Birding for casual identification: Monocular is fine. For serious birders cataloging species, binoculars win.

Monocular Tips for Hiking

Few specific tricks I've picked up:

• Wear it on a lanyard, not in a pocket. I scratched the objective lens of a previous unit by stuffing it in a cargo pocket with my keys.
• Pre-focus to mid-range. Set focus to roughly 50 yards before you stow it. You'll get a usable image immediately and only need minor adjustment.
• Carry a lens cloth. Sweat and condensation from temperature changes will fog the lens within an hour on humid trails.
• Mind the cold. Battery-powered units (thermal, digital night vision) lose significant runtime below 40F. The BETTITOPE BS02-13 lost about 30% of its rated runtime on a 35F morning. Check Price on Amazon

Common Mistakes to Avoid

• Skipping the diopter setup. You'll fight blurry images forever.
• Squinting your other eye. Headaches within twenty minutes, guaranteed.
• Cranking magnification too high. Above 10x, hand shake destroys image quality. Use a brace or accept a wider, steadier view.
• Cleaning the lens with your shirt. That'll add micro-scratches. Use a microfiber cloth or a lens pen.
• Storing with batteries inside in summer. Heat plus leaked batteries killed a unit of mine. Always pull batteries for long-term storage.
• Ignoring the strap. Drops happen. The wrist strap costs nothing and saves the device.

How We Tested

The LensSpan editorial team hands-on tested ten monoculars across roughly four months of mixed-use scenarios: dawn deer scouting in Pennsylvania hardwoods, urban observation from a 4th-floor apartment, daytime hiking on Appalachian trail sections, and indoor low-light testing in a windowless basement. We measured battery runtime against manufacturer claims, recorded detection ranges for human-sized and coyote-sized targets, and evaluated focus speed using a stopwatch from "raised to eye" to "image sharp."

Is a monocular better than binoculars for hiking? For weight-conscious hiking, yes. A 9-ounce monocular replaces a 28-ounce binocular for spotting and basic identification, though long glassing sessions are easier on the eyes with two eyepieces.

Why does my monocular image shake so much? Hand shake amplifies with magnification. Above 10x, brace against an object, use a two-handed grip with elbows tucked, and exhale halfway before viewing.

Can I use a monocular with glasses? Yes. Fold or retract the eyecup so the lens sits closer to your glasses, and set the diopter to compensate for your prescription if you ever use it without glasses.

What magnification should I get for a monocular? For general use, 8x is the sweet spot — strong enough to identify wildlife at 100+ yards but still hand-holdable. Go to 10x only if you'll regularly brace or use a monopod.

How do I keep both eyes open while using a monocular? Practice for short sessions (5-10 minutes) and let your brain learn to suppress the non-dominant eye. Most people get it within a week of regular use.

Are thermal monoculars worth it over digital night vision? For detection in pitch dark or through light brush, yes — thermal sees heat regardless of light. For identification and recording video, digital night vision is cheaper and produces a more recognizable image.

Sources & Methodology

Manufacturer specifications were cross-referenced with our timed battery and detection tests. Pricing reflects Amazon listings as of June 2026 and varies. Eye dominance and viewing technique guidance follows guidance commonly published by optics manufacturers and outdoor education programs.

Final Verdict

Using a monocular well comes down to three things: set your diopter once, keep both eyes open, and brace before you glass. Get those right and a $120 unit will outperform a $1,200 unit in untrained hands. Spend a week of short evening practice sessions and the technique becomes invisible — you'll just see clearly through the optic without thinking about it.

About the Author

The LensSpan editorial team independently researches and hands-on tests products in the optics category, from budget monoculars to premium thermal imagers. We don't accept manufacturer-paid placements and purchase test units at retail wherever possible.