Tele Vue Nagler T6 5mm 82° Eyepiece - 1.25"

Nagler Type 6 Optical Design for High Power

The 5mm Nagler T6 is built on a 7-element optical design that controls aberrations like astigmatism and field curvature, even at this demanding focal length. Using a unique pairing of high-index glasses, this design delivers sharp, high-contrast images from the center to the edge of the field. The result is a flat, well-corrected view that allows you to study fine planetary detail without constant re-centering.

This level of correction is what separates the Nagler from simpler wide-field designs. When you use the 5mm in a quality telescope, planetary limbs are sharp, and stars in the tight cores of globular clusters resolve into distinct points. It’s an optical system engineered to handle the high magnifications needed for detailed lunar and planetary work.

Fully Multi-Coated for Maximum Contrast

Every air-to-glass surface in the 5mm Nagler T6 receives a robust multi-coating optimized for maximum light throughput and minimal scatter. At high magnifications, where targets are often dim and subtle details are critical, this is not a luxury. The coatings ensure that the faint festoons in Jupiter's belts or the delicate Cassini Division in Saturn's rings are rendered with as much contrast as your telescope and seeing conditions will allow.

The lens edges are also blackened to further suppress internal reflections. This attention to detail reduces stray light, which enhances the perceived blackness of the space background. This makes faint objects, like the central stars of planetary nebulae, easier to detect against the sky.

The 82° Spacewalk Experience

The signature feature of any Nagler is the 82° apparent field of view. At the high power a 5mm focal length provides, this wide field is transformative. Instead of a narrow, restrictive view of a planet, you see the target suspended in a wide, black field of space, allowing you to observe for longer periods without the object drifting out of sight. This makes for a more relaxed and immersive session.

On a target like the globular cluster M13, the 5mm Nagler provides enough power to resolve the core while the 82° field frames the cluster beautifully. The experience is less like looking *at* an object and more like being *in* the starfield. This is the core of the "spacewalk" effect that made the Nagler design famous.

Consistent Eye Relief and Viewing Comfort

The Nagler T6 series was designed with a consistent 12mm of eye relief across all focal lengths. This means you can switch between them without having to significantly change your head position. The 5mm model features an adjustable rubber eyeguard that you can raise to set the perfect distance, which is crucial for blocking stray light and maintaining a stable view.

While 12mm of eye relief is not enough for observers who must wear glasses to correct for significant astigmatism, it is comfortable for most users. The design provides a generous eye lens, making the eyepiece feel less constricted than typical high-power oculars. This eyepiece is also compatible with Tele Vue's DIOPTRX astigmatism correctors.

Standard 1.25" Barrel and Filter Compatibility

The 5mm Nagler T6 uses a standard 1.25" barrel, making it compatible with the vast majority of telescopes and focusers. The barrel is threaded to accept standard 1.25" filters, a vital feature for planetary observers who rely on color filters to enhance specific details, like Mars's polar caps or Jupiter's Great Red Spot. The barrel also features a safety undercut to help prevent it from accidentally falling out of the focuser.

Small Form Factor for Easy Balancing

Unlike many extreme wide-field eyepieces, the Nagler T6 series is intentionally compact and lightweight. The 5mm model weighs only 7.2 ounces, which means it won’t cause significant balance issues when used in smaller refractors or on Dobsonians. Its size also means it is nearly parfocal with Tele Vue's Plössl eyepieces, minimizing the amount of refocusing needed when switching between low-power finding and high-power observing.

This makes the 5mm T6 an excellent choice for a "grab-and-go" kit. It provides the performance of a much larger eyepiece in a package that doesn't demand a heavy-duty mount or extensive counterweighting. It is a limitation, however, that the compact size contributes to its shorter eye relief compared to larger eyepieces like the Delos series.

Observing with the Nagler T6 5mm

On a night of steady seeing, place the 5mm Nagler T6 in a quality 8-inch Schmidt-Cassegrain telescope for a magnification of 406x. Center on Saturn. The planet and its rings fill a pleasing portion of the 82° field, leaving ample black space around them. As your eye settles, the Cassini Division snaps into focus as a sharp, dark line tracing the ansae.

You can hold the view for long stretches, watching the subtle banding on the planet's globe without the need to nudge the telescope constantly. The wide field makes tracking effortless, even on a manual mount. This is where the Nagler design proves its worth, combining high-power planetary reach with the comfort of a wide-field view.

Choosing Your High-Power Nagler

The Nagler T6 series offers several high-power options. The 5mm is often the right choice when you need a significant step up in magnification for planetary viewing or splitting tight double stars.

• vs. Nagler T6 7mm: The 7mm is an excellent all-around high-power eyepiece, but the 5mm provides a 40% increase in magnification. When seeing conditions are good, the 5mm will reveal finer detail on Jupiter and Saturn that the 7mm may only hint at. The 7mm is more forgiving on nights of average seeing.
• vs. Nagler T6 3.5mm: The 3.5mm pushes magnification to the limit for most telescopes and atmospheric conditions. The 5mm is a more versatile choice, hitting the sweet spot for high-power observing on more nights of the year. The 3.5mm is a specialist tool for exceptional seeing or for use with shorter focal length telescopes.