TeleVue Plössl 40mm 43° Eyepiece - 1.25"

The Limit of the 1.25" Format

The true field of view in an eyepiece is physically constrained by the inner diameter of the barrel. With a 27mm field stop, the TeleVue 40mm Plössl hits the absolute wall of what is possible in a 1.25" accessory. While it features a narrower 43° apparent field compared to the 32mm Plössl (50°), both eyepieces show the exact same amount of sky. The 40mm choice is specifically for those who prioritize a larger exit pupil and greater eye relief over apparent field width.

For observers using f/10 or f/12 instruments, the 40mm focal length provides the necessary exit pupil to keep images bright when hunting faint, extended objects like the North American Nebula or M31, where every photon counts.

Superior Contrast and Optical Coatings

TeleVue’s Plössl design uses high-index glass and proprietary multi-coatings to ensure maximum light transmission. In a four-element design, the reduction of air-to-glass surfaces minimizes scattering, providing a "jet-black" background that enhances the visibility of low-contrast deep-sky structures.

• Edge Correction: TeleVue Plössls are specifically corrected for astigmatism and aberrations at the edge of the field, even in faster focal ratios, though they truly excel in telescopes of f/6 and slower.
• Diffraction-Limited Performance: This is not a "budget" Plössl. It is built to the same exacting standards as the Delos or Nagler series, ensuring the 40mm focal length doesn't introduce unwanted flare or ghosting.
• Chrome-Plated Barrels: Precision-machined barrels with safety undercuts ensure the eyepiece sits securely and square in the optical axis, maintaining collimation integrity.

Exceptional Comfort for Eyeglass Wearers

With 28mm of eye relief, the 40mm Plössl is one of the most comfortable eyepieces in the TeleVue catalog. If you suffer from astigmatism and must observe with your glasses on, this eyepiece allows you to see the entire field stop without pressing your lenses against the rubber guard.

• Dioptrx Compatibility: The 40mm Plössl is fully compatible with the TeleVue Dioptrx system. This allows you to attach a professional-grade astigmatism corrector directly to the eyepiece, finally allowing you to observe without spectacles while maintaining a perfect point-spread function.
• Adjustable Eye Guard: To prevent stray light and help position the eye for those not wearing glasses, the eyepiece features a fold-down rubber eyeguard that assists in maintaining the proper exit pupil distance.

Technical Trade-offs: 40mm vs. 32mm

A common question among experienced observers is whether to choose the 32mm or 40mm Plössl. Since both share the 27mm field stop, the true field of view is identical.

• The 40mm Advantage: Provides a 25% larger exit pupil. This makes the image appear brighter in slow telescopes (f/10+) and is often preferred for use with narrow-band filters (OIII, H-Beta).
• The 32mm Advantage: Provides higher magnification and a wider 50° apparent field, which darkens the sky background—a benefit for city-dwelling observers battling light pollution.