Tele Vue Panoptic 24mm 68° Eyepiece - 1.25"

The 27mm Field Stop: Maximum True Field in a 1.25" Barrel

The true field of view you see is determined by the eyepiece's internal field stop diameter and your telescope's focal length. The Panoptic 24mm's 27mm field stop is the 1¼" maximum in Al Nagler's guide. Tele Vue's 32mm Plössl also has a 27.0mm field stop, so both show the same true field, the Panoptic at more magnification.

To calculate your true field of view (TFoV), use the formula: TFoV = (Eyepiece Field Stop ÷ Telescope Focal Length) x 57.3. For example, in a telescope with a 1000mm focal length, the Panoptic 24mm delivers a true field of (27mm / 1000mm) * 57.3 = 1.55°. That fits the Pleiades (M45) and the Double Cluster, and suits sweeping the Milky Way; the Andromeda Galaxy (M31), about 3° long, needs a shorter telescope.

6 Elements, 68° Field and Exit Pupils

The Panoptic 24mm has 6 elements in 4 groups. Al Nagler's guide gives Panoptics a 68° apparent field, against 50° for Plössls and 82° for Naglers.

• Exit Pupil Characteristics: Tele Vue's chart gives 5.3, 4.6, 3.4, 2.4 and 1.7mm at f/4.5, f/5.2, f/7, f/10 and f/14.
• Weight: 8.2 oz (232 g).

15mm Eye Relief and Dioptrx Compatibility

The Panoptic 24mm has 15mm of eye relief, the low end of the 15mm to 20mm suggested for observers who wear glasses to correct astigmatism.

For those who require astigmatism correction, the Panoptic 24mm is compatible with Tele Vue's Dioptrx system. The chart marks it Y*, adapter required: Tele Vue's DEA / DNA adapters convert eyepieces with small eyeguards to larger eyeguards so Dioptrx fits. Dioptrx corrects astigmatism in place of glasses and comes in ¼ to 3½ diopters.

Fast Newtonian Performance with the Paracorr Type-2

Owners of fast Newtonian and Dobsonian reflectors (f/5 or faster) will notice that stars at the edge of the field can appear elongated, a common aberration known as coma. 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.

The 24mm then acts like a 20.9mm. The Paracorr keeps faint stars from disappearing at the edge of the field and reduces the need to keep nudging the scope to hold an object in the "sweet spot."

Magnification Versatility with Barlows & Powermates

While the Panoptic 24mm excels at wide-field observing, its magnification can be easily increased using Tele Vue's image amplifiers. A 2x Barlow lens will effectively turn it into a 12mm eyepiece, doubling the power for closer views of globular clusters or lunar craters. Tele Vue makes Barlows and Powermates in 2x, 2.5x, 3x, 4x and 5x.

Building an Eyepiece Set: Panoptic 24mm vs. Plössl 32mm and Panoptic 19mm

Choose low and medium power eyepieces in field stop ratios such as 1.4 or 2.0. With the 1¼" maximum 27mm field stop, the 24mm is the widest-field 1¼" eyepiece in a set.

• vs. Tele Vue 32mm Plössl: Both eyepieces have a 27mm field stop and show the exact same amount of sky. The Panoptic gives more magnification, a smaller exit pupil and a 68° apparent field against the Plössl's 50°; the Plössl has 22mm of eye relief and is Dioptrx ready (Y).
• vs. Tele Vue 19mm Panoptic: The 19mm Panoptic uses a smaller 21.3mm field stop, showing a narrower true field but at higher power. Both have a 68° field; the 19mm has 13mm of eye relief, and both need the Dioptrx adapter (Y*).