Why is the Tele Vue Delos 24mm a 2-inch eyepiece while other Delos models are 1.25-inch?
Its 29.6mm field stop is larger than the 27mm maximum for a 1¼" eyepiece (46mm for 2"). A 24mm focal length with a 72° field needs that field stop, so the 24mm Delos is a 2" model only.
How does the Delos 24mm perform in a fast f/4.5 Dobsonian?
In a fast Dobsonian, the Tele Vue Delos 24mm works well; Tele Vue's Paracorr Type-2 is the companion for fast mirrors. The Paracorr will correct the coma inherent in fast parabolic mirrors, so stars stay sharp toward the edge of the 72° field. The eyepiece will produce a bright 5.3mm exit pupil, good for sweeping for faint galaxies and viewing large nebulae.
Can I use the Tele Vue Delos 24mm for planetary viewing?
It is mainly a deep-sky eyepiece. In long focal length telescopes such as SCTs it gives a moderate power for a first look at a planet; for planetary detail, pair it with a Tele Vue Barlow or Powermate or use a shorter Delos.
I wear glasses for astigmatism. Is the Delos 24mm a good choice?
Yes. The 22mm of eye relief is above the 15mm to 20mm suggested for eyeglass wearers. The eyepiece is also compatible with Tele Vue's DIOPTRX astigmatism correctors, which replace the need for glasses at the eyepiece and are more likely to give a sharper, higher-contrast image than eyeglasses.
What is the exit pupil of the Delos 24mm with my f/10 SCT?
The exit pupil is calculated by dividing the eyepiece focal length by the telescope's focal ratio. For the Delos 24mm in an f/10 telescope, the exit pupil would be 2.4mm (24mm / 10). That suits galaxies and globular clusters (Tele Vue chart: 2.4mm at f/10).
How do I adjust the eyeguard on the Tele Vue Delos 24mm?
The eyeguard has a locking mechanism. To adjust it, 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. You can then slide the eyeguard up or down. Once you find your ideal position, twist the lower ring to the right to lock it in place.
Is the Delos 24mm better than the Panoptic 24mm?
"Better" depends on your needs. The Delos 24mm offers a wider apparent field (72° vs 68°), a larger true field, and significantly more eye relief (22mm vs 15mm), However, the Panoptic 24mm uses a 1.25" barrel, making it lighter and more compatible with smaller telescopes. If your setup takes a 2" eyepiece and you value eye relief, the Delos fits that need.
What's the best way to build an eyepiece set around the Delos 24mm?
Build a set by choosing eyepieces with field stops that decrease in uniform increments. The Delos 24mm has a 29.6mm field stop. A good next step for higher power would be an eyepiece with a field stop around half that size (approx. 15mm), such as the Tele Vue Delos 12mm. This approach ensures you are getting meaningfully different true fields of view with each eyepiece.
Will the Delos 24mm eyepiece show me more of the sky than a 31mm Nagler?
No. The true field of view is limited by the field stop and telescope focal length. The 31mm Nagler has a 42mm field stop, while the Delos 24mm has a 29.6mm field stop. In the same telescope, the 31mm Nagler will show a significantly wider true field of view. The Delos 24mm will provide higher magnification.
Can I use the Tele Vue Delos 24mm for smartphone astrophotography?
Yes. The Delos 24mm is compatible with Tele Vue's FoneMate smartphone adapter. The FoneMate clamps to compatible Tele Vue eyepieces for still, video or timelapse images.
