Tele Vue DeLite 15mm 62° Eyepiece - 1.25"

DeLite Series: 62° Field and 20mm Eye Relief

Tele Vue's DeLite manual says each DeLite has 20mm of eye relief and a 62° apparent field, and that its Delos design experience let it keep the size and weight down.

It achieves the best sharpness, linearity (freedom from pincushion distortion) and ghost suppression over the entire field for any speed (f/#) telescope.

The 16.0mm Field Stop: Calculating True Field of View

The true field, how much sky you see, depends on the field stop diameter and the telescope's focal length. The DeLite manual lists 16.0mm for the 15mm. Tele Vue's formula:

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

• In a Tele Vue-76 (480mm focal length): (16.0mm / 480mm) x 57.3 = 1.91° of true field, about the size of the Pleiades (M45), which just fill it.
• In an 8" f/10 SCT (2032mm focal length): (16.0mm / 2032mm) x 57.3 = 0.45° of true field at 135x, room for the globular cluster M13.

Exit Pupils from f/4.5 to f/14: Matching Eyepiece to Telescope

The exit pupil, eyepiece focal length divided by the telescope's focal ratio, sets how bright the view looks.

Tele Vue's chart gives:

• f/4.5 (Fast Dobsonian): 3.3mm exit pupil, for nebulae and galaxies.
• f/5.2 (Dobsonian with Paracorr): 2.9mm exit pupil.
• f/7 (Apochromatic Refractor): 2.1mm exit pupil, a darker background for star clusters and planetary nebulae.
• f/10 (Schmidt-Cassegrain): 1.5mm exit pupil, 135x in an 8" SCT, for the Moon and planets.
• f/14 (Maksutov-Cassegrain): 1.1mm exit pupil, for double stars.

Ergonomics: The Adjustable, Locking Eyeguard Mechanism

The DeLite's adjustable, locking eyeguard housing is in two pieces. With this much eye relief it is important to learn your own position: an eye too far in or out causes edge darkening and field loss.

To operate the eyeguard, grasp the upper rubber grip with one hand and the lower grip ring with the other. Twist the lower ring to the left to loosen it. Without glasses, 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 on the inner barrel, then leave it loose or lock it by twisting the lower ring to the right. Tele Vue cautions against unscrewing the lower barrel section when rotating the housing.

20mm Eye Relief: A Clear View with Eyeglasses or Dioptrx

The locking eyeguard housing gives eyeglass wearers full eye relief in the down position. 20mm is at the top of the 15mm to 20mm suggested for observers who wear glasses to correct astigmatism.

The DeLite is ideal for DIOPTRX, which attaches and locks onto the top and replaces your glasses; the chart marks the 15mm Y, no adapter. Dioptrx is always completely aligned to the eyepiece optics, so you're more likely to see a sharper, higher contrast image.

System Integration: Use with Paracorr, Barlows, and Powermates

Tele Vue's material covers both:

• Paracorr Type-2: It eliminates the coma of Newtonians and Dobsonians, with the greatest results in those faster than f/5.0. Its 1.15x factor makes the DeLite 15mm act like a 13mm.
• Barlows and Powermates: Tele Vue makes them in 2x, 2.5x, 3x, 4x and 5x. A 2x makes the 15mm act like a 7.5mm.

DeLite 15mm vs. Delos 14mm and Plössl 15mm

Comparisons from Tele Vue's chart:

• vs. Tele Vue 14mm Delos: The Delos offers a wider, more immersive 72° apparent field and a slightly larger 17.3mm field stop. The Delos weighs 14.4 oz against the DeLite's 7.5 oz. Both have 20mm of eye relief and are Dioptrx ready.
• vs. Tele Vue 15mm Plössl: The Plössl has a 50° field, a 12.6mm field stop, 10mm of eye relief and no Dioptrx (N). The DeLite has 62°, 16.0mm, 20mm and Dioptrx (Y).

Build, Accessories, and Lifetime Limited Warranty

The DeLite 15mm weighs 7.5 oz (213 g). The 1¼" barrel takes M28.5x0.6 filters, and Tele Vue's insert lists BandMate filters. The manual warns: "To avoid getting dust and dirt into the eyepiece Do not unscrew the chrome barrel!"

Its manual also lists the FoneMate smartphone adapter (SFA-0001), which clamps to the eyepiece for still, video or timelapse images. Tele Vue eyepieces carry a Lifetime Limited warranty against defects in material or workmanship.