The Spacewalk View, Now in High Power
The Tele Vue Nagler T7 5.5mm 82° eyepiece brings the legendary "spacewalk" viewing experience to high-magnification targets. This eyepiece is engineered to deliver an expansive, sharp, and immersive field of view, transforming your observations of planets, double stars, and compact deep-sky objects. It leverages Al Nagler's original wide-field design philosophy to correct for aberrations that plague simpler eyepieces at the edge of the field, especially in fast telescopes.
The Seven-Element Nagler Optical Design
At the heart of the 5.5mm Nagler is a seven-element optical configuration. This design is not just about creating a wide field; its primary purpose is to deliver a sharp, flat field by actively correcting for aberrations like coma and astigmatism. For owners of fast Newtonian reflectors or Dobsonians (f/4 to f/5), this means stars at the edge of the field remain sharp points, not distracting comets or seagulls.
This level of correction allows you to use the entire field of view with confidence. You can place a planet at the edge and let it drift across the field without it distorting or losing focus. The result is a more natural and comfortable observing session, as your eye is not forced to concentrate only on the "sweet spot" in the center.
An Immersive 82° Apparent Field of View
The 82° apparent field of view is the defining characteristic of the Nagler experience. This wide vista fills your eye's natural peripheral vision, creating a sensation of being immersed in the starfield rather than looking through a narrow tube. The effect is that the eyepiece body seems to disappear, leaving only the target suspended in space.
On a target like the Orion Nebula (M42), the 5.5mm focal length provides the power to resolve the Trapezium star cluster at the core, while the 82° field is wide enough to frame the surrounding nebulosity. This combination of power and field width is difficult to achieve with conventional eyepiece designs and is what makes the Nagler a versatile instrument for both planetary and deep-sky work.
Maximizing Contrast with Advanced Coatings
Every glass-to-air surface in the Nagler T7 5.5mm is fully multi-coated with Tele Vue's proprietary anti-reflective coatings. This ensures that the maximum amount of light from the telescope reaches your eye, which is critical for observing faint planetary details or teasing out dim stars. The coatings are tuned to provide a neutral color balance, rendering the ruddy tones of Mars or the subtle blues and greens of planetary nebulae accurately.
To further enhance contrast, the lens edges are meticulously blackened. This absorbs stray light that can bounce between elements, which would otherwise reduce contrast and wash out fine detail. This attention to internal baffling is what gives Tele Vue eyepieces their characteristically high-contrast, "contrasty" views, where the background sky appears truly black.
High Power in a Compact 1.25" Barrel
Despite its complex optical design, the 5.5mm Nagler is housed in a compact and lightweight 1.25" barrel. This makes it compatible with nearly any telescope, from small refractors to large Dobsonians, without causing significant balance issues. The smaller format is particularly useful for binoviewing, where the weight and size of two eyepieces are a primary concern.
The single biggest trade-off for this compact power is its 12mm of eye relief. While comfortable for many observers, it can be tight for those who must wear eyeglasses to correct for significant astigmatism. For those observers, the Tele Vue Delos line may be a more suitable choice if longer eye relief is the top priority.
Practical Observing with the Nagler 5.5mm
In a telescope with a 1000mm focal length, this eyepiece yields 182x magnification. Point it at Jupiter on a night of steady seeing, and the view is electric. The 82° field means you can watch the planet and its Galilean moons drift across the eyepiece for a long time before needing to nudge the scope, and the high-contrast optics will resolve distinct cloud bands and, conditions permitting, the Great Red Spot.
Move to a dense globular cluster like M13. The high power resolves the core into a spray of individual stars, while the wide field of view frames it against the dark background sky. This ability to deliver both resolving power and a rich context is what defines the Nagler T7 5.5mm as a premier high-performance eyepiece.
Is the Nagler 5.5mm good for planetary viewing?
Yes, it is an excellent choice for high-power planetary observation. Its sharp optics and high contrast excel at revealing fine details in Jupiter's cloud bands, Saturn's rings, and features on the surface of Mars, provided atmospheric seeing is good.
Will I need a Paracorr with this eyepiece in my Dobsonian?
In fast Dobsonians (f/5 or faster), a Paracorr is highly recommended. While the Nagler design corrects for many aberrations, adding a Paracorr will ensure the sharpest possible stars across the entire 82° field of view.
How does the Nagler T7 5.5mm compare to the Nagler T6 5mm?
Both are top-tier high-power eyepieces. The T7 5.5mm offers a slightly less powerful, brighter view, while the T6 5mm provides a bit more magnification. The choice depends on the specific focal length of your telescope and which magnification falls into your most-used range.
Is the 12mm eye relief enough for glasses?
The 12mm of eye relief is generally considered too short for observers who need to wear glasses to correct for astigmatism. For a more comfortable experience with glasses, consider the Tele Vue Delos line, which features 20mm of eye relief.
What's the best way to clean the Nagler 5.5mm eyepiece?
First, use a blower bulb to remove any dust or grit. For fingerprints or smudges, use a high-quality optical cleaning fluid and a microfiber cloth. Apply the fluid to the cloth, not directly to the lens, and wipe gently in a circular motion from the center outwards.
