Tele Vue DeLite 18.2mm 62° Eyepiece - 1.25"

The DeLite 62° Concept: Sharpness, Linearity, and Contrast

Each DeLite has 20mm of eye relief and a 62° apparent field. Drawing on Tele Vue's Delos design experience, the DeLite keeps the size and weight down while achieving the best sharpness, linearity (freedom from pincushion distortion) and ghost suppression over the entire field for any speed (f/#) telescope.

Understanding the 19.1mm Field Stop and True Field

The field stop is the ring inside the barrel that limits the field. The 18.2mm has a 19.1mm field stop, the largest in the line. It is not the 1¼" maximum, which is 27mm.

To calculate the true field for your telescope, use Tele Vue's formula: TFoV = (Eyepiece Field Stop ÷ Telescope Focal Length) × 57.3. For example, in a telescope with a 1200mm focal length, the DeLite 18.2mm would yield a true field of (19.1mm ÷ 1200mm) × 57.3 ≈ 0.91 degrees, nearly twice the full Moon's width. The Pleiades (M45), about 2° across, need a shorter telescope: in a TV-76 (480mm) the field is 2.3°.

20mm Eye Relief and the Adjustable Locking Eyeguard

The DeLite is designed for optimum viewing whether or not you wear eyeglasses; 20mm is at the top of the 15mm to 20mm suggested for eyeglass wearers. The adjustable, locking eyeguard housing is in two pieces: grasp a grip ring with each hand and twist the lower ring to the left to loosen it, to the right to tighten.

• For Eyeglass Wearers: In the down position the housing gives full eye relief.
• Without Eyeglasses: Pull the eyeguard fully out, then slide it down while looking through the eyepiece until you just see the full field with your peripheral vision. Note the height with the green indicator lines engraved on the inner barrel.
• Locking Mechanism: Leave it loose or lock it by turning the lower grip ring to the right. The system minimizes outside light for the highest contrast, and the 20mm of eye relief minimizes eye lens fogging in cold weather. Be careful not to unscrew the lower barrel section when rotating the housing.

System Integration: Performance with Paracorr, Powermates, and Dioptrx

The DeLite is ideal for DIOPTRX (Y in the chart), which attaches and locks onto the top and corrects astigmatism in place of glasses. It also works with the FoneMate smartphone adapter (SFA-0001), which clamps to the eyepiece for still, video or timelapse images, and BandMate filters.

For owners of fast Newtonian and Dobsonian telescopes (f/5 or faster), coma can soften stars at the edge of the field. Tele Vue's Paracorr Type-2 eliminates coma, with the greatest results in scopes faster than f/5.0. It has a 1.15x magnification factor, so the 18.2mm acts like a 15.8mm. Tele Vue makes Barlows and Powermates in 2x, 2.5x, 3x, 4x and 5x; a 2x makes it act like a 9.1mm.

DeLite 18.2mm vs. Delos 17.3mm and Panoptic 19mm

Comparisons from Tele Vue's chart:

• vs. Delos 17.3mm: The Delos offers a wider 72° apparent field. It has a 21.2mm field stop and weighs 14.4 oz against the DeLite's 7.6 oz. Both have 20mm of eye relief and are Dioptrx ready.
• vs. Panoptic 19mm: The Panoptic has a wider 68° apparent field and a larger 21.3mm field stop, providing a slightly larger true field of view. The DeLite has 20mm of eye relief against 13mm and accepts Dioptrx without an adapter (Y against Y*).

Building a Set: Choosing Eyepieces by Field Stop Increments

Build a set in uniform steps of field stop diameter. A factor of 2 halves the diameter, a 4x decrease in area; a factor of 1.4 also works.

The DeLite 18.2mm, with its 19.1mm field stop, fits perfectly into this system. From a 35mm Panoptic (38.7mm), the 18.2mm is a factor-2 step; the 9mm DeLite (9.6mm) is the next. With 1.4 steps, the 13mm DeLite (13.8mm) sits between.