Using a spyglass is straightforward: extend the draw tubes, hold it to your eye, and slide the tubes in or out until the image snaps into focus. But getting a crisp, steady view takes a bit of technique, and keeping your spyglass in good shape requires some basic care. Here’s everything you need to know.
How to Extend and Collapse the Tubes
A traditional spyglass is a refracting telescope with nested brass or metal tubes that slide inside one another. To open it, grip the main barrel in one hand and gently pull the smallest tube (closest to your eye) outward. If there are multiple draw tubes, extend each one in sequence until the spyglass is at full length. You should feel a slight resistance as each section seats into place.
To collapse it, reverse the process: push each tube back in starting with the one nearest your eye. Never force a stuck tube by twisting hard, as this can scratch the interior and misalign the optics. If a section won’t budge, warm it slightly with your hands to loosen any moisture or corrosion that may have seized the joint.
Focusing for a Clear Image
Once fully extended, point the spyglass at a distant, well-lit object like a rooftop or tree line. Slowly slide the innermost draw tube in or out in small increments. You’re changing the distance between the objective lens (the large one at the front) and the eyepiece lens, which shifts the focal point until it lands precisely on your eye. When the image looks sharp, stop.
Closer objects require the tubes to be extended slightly farther apart, while very distant targets need them pushed slightly closer together. Each time you change targets at a different distance, you’ll need to re-focus. The adjustment is subtle, often just a few millimeters, so move slowly. If the image gets blurrier in both directions and you can’t find a sweet spot, make sure all tubes are fully seated and none are cocked at an angle.
Where to Place Your Eye
The eyepiece creates a small bright disk of light called the exit pupil, which floats a short distance above the lens. Your eye needs to be at that exact distance to see the full, unobstructed image. Too close and your eyelashes will brush the glass. Too far and you’ll see a shrinking circle surrounded by a dark ring (called vignetting).
For most spyglasses, the sweet spot is about 10 to 15 millimeters from the eyepiece, roughly the width of your pinky finger. If you wear glasses, look for eyepieces with longer eye relief in the range of 25 to 30 millimeters, which gives enough clearance for your lenses. Start by holding the spyglass just off your eye socket and slowly bringing it closer until the dark edges disappear and the image fills your view completely.
Holding It Steady
A spyglass magnifies everything, including the natural tremor of your hands. Brace your elbows against your ribs, a railing, or a windowsill. If you’re standing in the open, widen your stance and press the barrel against a post, tree trunk, or any solid surface. Exhale slowly while you look, the same way a marksman steadies a shot. Even small improvements in stability make a dramatic difference in image clarity at high magnification.
Cleaning the Lenses
Dust and fingerprints are the most common enemies of a clear view. Clean your lenses with a simple kit: a rubber bulb puffer (an ear syringe from the pharmacy works), cotton swabs, and plain facial tissue with no perfumes or lotions.
- Blow first. Use the bulb puffer to remove loose dust and grit. Never blow with your mouth, as tiny saliva droplets will leave spots on the glass.
- Blot stuck particles. If anything remains, lightly moisten a tissue or cotton swab with glass cleaner (Windex works) and gently blot the surface without rubbing.
- Wipe for smudges. Moisten a fresh cotton swab or tissue with rubbing alcohol or reagent-grade acetone and wipe gently from the center outward in a slow circular motion. Move slowly enough that the liquid follows the swab and gets reabsorbed rather than pooling. Use a fresh swab for each pass to avoid dragging contaminants back across the glass.
Avoid nail polish remover, which contains perfumes and oils that leave a film. The same goes for scented or lotion-infused tissues.
Storing Your Spyglass
Keep your spyglass in a cool, dry, dust-free spot at room temperature. Moisture is the biggest long-term threat: glass fungus, a type of mold, can permanently etch optical surfaces when lenses are stored in warm, humid conditions. Always replace the dust caps on both ends before putting it away. Those caps protect the interior from dust, pollen, and insects.
If you’ve been using the spyglass outdoors in cold or damp conditions, don’t immediately seal it in a case. Put the dust caps on, bring it inside, and let it warm to room temperature gradually so condensation can evaporate. Only close the storage case once everything is completely dry. It doesn’t matter whether you store it pointing up, down, or sideways, as long as the caps are on and moisture stays out.
Protecting Brass From Corrosion
Brass spyglasses are especially vulnerable near saltwater. The zinc in brass can leach out over time when exposed to salt air and moisture, a process called dezincification that weakens the metal and leaves it pinkish and porous. Wipe the exterior with a dry cloth after every outing, and apply a thin protective wax or lacquer coating to exposed brass surfaces. This coating has a limited lifespan, so inspect it periodically and reapply when it starts to wear through or flake.
Vintage spyglasses made with older alloy formulations that include a small amount of tin (sometimes called admiralty brass) hold up better against this kind of corrosion. If you own a modern reproduction, it’s worth being more diligent about drying and coating the metal after any exposure to humid or salty environments.
Fixing Sticky or Loose Draw Tubes
Over time, draw tubes can become either too tight (from corrosion, grime, or temperature changes) or too loose (from wear on the friction surfaces). If a tube is stiff, collapse the spyglass and clean the outside of each inner tube and the inside lip of each outer tube with a soft cloth dampened with a small amount of alcohol. Remove any grit or buildup, then extend the tubes again. A very light application of dry lubricant can help, but avoid oily or greasy products that could migrate onto the lenses.
If the tubes are too loose and slide freely without holding position, look for small set screws or tension adjustment screws along the barrel. Tightening these increases friction on the draw tube so it stays where you put it. Some spyglasses also have a locking thumbscrew near the eyepiece that you can snug down once you’ve found focus. If your spyglass lacks these features and the tubes won’t stay extended, a thin wrap of cotton thread around the base of the inner tube can add just enough friction to hold it in place.