Tele Vue Panoptic 19mm 68° Eyepiece - 1.25"

A 19mm, 68° Medium-Power Eyepiece

Al Nagler's guide gives Panoptics a 68° apparent field, against 50° for Plössls and 82° for Naglers. At 19mm the magnification darkens the sky background on galaxies and nebulae while the field still frames open clusters.

Calculating True Field: The 21.3mm Field Stop in Your Telescope

The true field, the patch of sky you see, depends on the field stop diameter and your telescope's focal length. The Panoptic 19mm has a 21.3mm field stop. Tele Vue's formula:

True Field (°) = (Eyepiece Field Stop ÷ Telescope Focal Length) x 57.3

For example, in a telescope with a 1000mm focal length, the Panoptic 19mm yields a true field of 1.22°. In a larger Schmidt-Cassegrain with a 2000mm focal length, it gives 105x and a 0.61° true field, room for the Hercules Cluster (M13) or the small Ring Nebula (M57).

Exit Pupil & System Speed: Performance from f/4.5 to f/14

The exit pupil, the beam of light leaving the eyepiece, sets how bright the view looks. Divide the eyepiece focal length by the telescope's focal ratio.

Tele Vue's chart gives 4.2, 3.7, 2.7, 1.9 and 1.4mm at f/4.5, f/5.2, f/7, f/10 and f/14:

• At f/4.5 (Fast Dobsonian): 4.2mm exit pupil, for sweeping the Milky Way.
• At f/7 (Apochromatic Refractor): 2.7mm exit pupil, a darker background for galaxies and nebulae.
• At f/10 (Schmidt-Cassegrain): 1.9mm exit pupil, for globular clusters and planetary nebulae.
• At f/14 (Maksutov-Cassegrain): 1.4mm exit pupil, a medium power for smaller targets.

Observing Comfort: 13mm Eye Relief and Dioptrx Compatibility

With 13mm of eye relief, the Panoptic 19mm requires you to get close to the lens to see the full 68° field. Observers who wear glasses to correct astigmatism are best served by 15mm to 20mm of eye relief, so with glasses you may not see the whole field.

For the sharpest possible views, this eyepiece is compatible with the Tele Vue Dioptrx astigmatism corrector. The Panoptic 19mm is marked as "Y*", meaning it requires a DEA/DNA adapter to fit the Dioptrx unit. Tele Vue's DEA / DNA adapters convert eyepieces with small eyeguards to larger eyeguards so Dioptrx fits. Dioptrx is always completely aligned to the eyepiece optics, and you're more likely to see a sharper, higher contrast image than with eyeglasses.

Correcting Fast Optics: The Panoptic 19mm with Paracorr Type-2

Newtonian and Dobsonian telescopes show coma, which makes off-center stars look like little comets; no eyepiece removes it. Tele Vue's Paracorr Type-2 eliminates it, with the greatest results in scopes faster than f/5.0.

It goes in a 2" focuser like a 2" Barlow and has a 1.15x magnification factor, so the 19mm acts like a 16.5mm and the exit pupil gets slightly smaller. With Tele Vue eyepieces an object will be equally sharp anywhere in the field.

Panoptic 19mm vs. The Alternatives: Building Your Eyepiece Set

Comparisons from Tele Vue's chart:

• vs. Panoptic 24mm: The 24mm Panoptic has a 27.0mm field stop, the 1¼" maximum in Al Nagler's guide, and 15mm of eye relief. The 19mm gives 26% more magnification and a darker sky background.
• vs. Nagler 16mm Type 5: The 16mm Nagler offers a more immersive 82° apparent field and a slightly larger 22.1mm field stop. It has 10mm of eye relief and is marked N for Dioptrx; the 19mm Panoptic has 13mm and accepts Dioptrx with an adapter (Y*).

Choose low and medium power eyepieces in field stop ratios such as 1.4 or 2.0. From the 19mm's 21.3mm, a 1.4 step lands near 15mm, such as the 12mm Delos (15.0mm).