Tele Vue DeLite 13mm 62° Eyepiece - 1.25"

The DeLite Line

Each DeLite has 20mm of eye relief and a 62° apparent field. Based on Tele Vue's Delos design experience, it 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.

The 13mm is a medium-power eyepiece: 156x in an 8" SCT, 46x in a TV-85.

The 13.8mm Field Stop and True Field Calculation

The true field depends on the field stop diameter and the telescope's focal length. The DeLite manual lists 13.8mm for the 13mm.

You can calculate the true field for the DeLite 13mm on your telescope using Tele Vue's formula:

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

• On a Tele Vue TV-85 (600mm FL): (13.8mm ÷ 600mm) x 57.3° = 1.32° true field.
• On an 8" f/10 SCT (2032mm FL): (13.8mm ÷ 2032mm) x 57.3° = 0.39° true field, room for the globular cluster M13.

Exit Pupils from 0.9mm to 2.9mm Across Common f-ratios

The exit pupil, the beam of light leaving the eyepiece, sets how bright the view looks.

Exit Pupil is calculated as: Eyepiece Focal Length ÷ Telescope f-ratio. Tele Vue's chart gives:

• 2.9mm at f/4.5: for nebulae in fast Dobsonians.
• 2.5mm at f/5.2
• 1.9mm at f/7: for galaxies and planetary nebulae.
• 1.3mm at f/10: for the Moon and planets in SCTs.
• 0.9mm at f/14: for double stars in Maksutov-Cassegrains.

20mm Eye Relief with a Locking Adjustable Eyeguard

Every DeLite has 20mm of eye relief, at the top of the 15mm to 20mm recommended for eyeglass wearers. The adjustable, locking eyeguard housing gives eyeglass wearers full eye relief in the down position.

Without glasses, grasp a grip ring in each hand and twist the lower one to the left to loosen it, 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, then leave it loose or twist the lower ring to the right to lock it. This minimizes outside light; take care not to unscrew the lower barrel section when rotating the housing.

DeLite 13mm vs. Delos 12mm & Nagler 13mm: A Comparison

Comparisons from Tele Vue's chart:

• vs. Tele Vue Delos 12mm: 72° apparent field, 15.0mm field stop, the same 20mm of eye relief, and 14.4 oz against the DeLite's 7.8 oz.
• vs. Tele Vue Nagler Type 6 13mm: 82° apparent field and a 17.6mm field stop, so more sky, with 12mm of eye relief and Dioptrx only with an adapter (Y*). The DeLite has 20mm and takes Dioptrx directly (Y).

Coma Correction with Paracorr Type-2 in Fast Newtonians

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, and scopes faster than f/5.0 see the greatest results.

It goes in a 2" focuser like a 2" Barlow and has a 1.15x magnification factor, so the 13mm acts like an 11.3mm. With Tele Vue eyepieces an object will be equally sharp anywhere in the field.

Reaching Higher Powers with Barlows & Powermates

Tele Vue makes Barlows and Powermates in 2x, 2.5x, 3x, 4x and 5x.

• With a 2x Barlow: the 13mm acts like a 6.5mm.
• With a 3x Barlow: it acts like a 4.3mm, 140x in a TV-85.

Weight and Accessories

The DeLite 13mm weighs 7.8 oz (221 g). The manual warns: "To avoid getting dust and dirt into the eyepiece Do not unscrew the chrome barrel!"

The DeLite is ideal for DIOPTRX (Y in the chart), which 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; the barrel takes M28.5x0.6 filters.