Revamped Insight: Celestron Luminos Eyepieces Evaluation - A Suggested Choice
Going for the Ultra-Wide Angle: A Deep Dive into Celestron's Luminos Eyepieces
Dive into the world of ultra-wide-angle (UWA) eyepieces with Celestron's Luminos line, a popular choice amidst fierce competition. These eyepieces come in six focal lengths for both 2" and 1.25" barrels, offering a decent pick for UWA design enthusiasts.
Celestron's arsenal includes a 2.5x, 2" Luminos-branded Barlow lens, which performs well, but it might not be your optimal choice due to its weight and questionable necessity for a 2" Barlow lens.
Picking Your Luminos
If you're looking for a standout among the 2" Luminos oculars, the 31mm might be your best bet. Although it's heavy and has noticeable edge-of-field brightening, its nearly max true field is a selling point. You might want to skip the 23mm and potentially the 15mm, while the 10mm and 7mm eyepeces offer few flaws. The 10mm Luminos, in particular, shines as the star of the show and is a fantastic medium to high-power eyepiece.
Optical Design and Performance
The Celestron Luminos eyepieces share similarities with the well-known Tele-Vue Nagler optical design. The apparent field of view, like the Nagler, is set at 82 degrees. A unique feature of the Luminos design is angular magnification distortion, which causes the edges of the field of view to be "compressed," resulting in a 26% decrease in the case of the 23mm Luminos. This distortion leads to brighter background skies toward the edges, a complaint among many users.
You'll likely only notice this edge-of-field brightening under moderately light-polluted skies while observing deep-sky objects at low power without a filter. Darker skies will diminish the effect, while severely light-polluted skies will be so bright that the subtle brightening is un noticeable. High powers will also dim the background, making the brightening less visible. The edge-of-field brightening is primarily due to the combination of the actual sky background and internal reflections within the eyepiece.
Remarkably, the 10mm and 7mm Luminos eyepieces, produced by Kunming United Optics, have almost no angular magnification distortion, making edge-of-field brightening an inconsequential issue.
A chart detailing the specifics of each eyepiece and the specs for angular magnification distortion can be found below. The edge-of-field brightening severity is calculated based on the background sky brightness and angular magnification distortion in a given telescope, relative to what the 23mm Luminos would show. The 31mm Luminos has lower angular magnification distortion compared to the other eyepieces in the lineup, but its lower magnification makes edge-of-field brightening more pronounced.
The calculations from the chart hold up across various telescopes and their optical designs, demonstrating the consistency of the Luminos eyepieces' performance.
Mechanics and Alternatives
The Luminos eyepieces boast a sturdy, metal housing with a rubber grip ring. Twisting this ring adjusts a twist-up eyecup, a design similar to the old Meade Series 5000 UWAs. The eyecup is comfortable once properly set, but its bulk and weight are drawbacks.
One interesting feature of the Luminos eyepieces is their "decloaking" capability. This process involves jerry-rigging new eyeguards and top caps, offering a means to minimize weight and volume or use the 1.25" 15mm, 10mm, or 7mm Luminos eyepieces in a binoviewer.
If the Luminos line isn't quite meeting your needs, alternatives such as the Meade PWA and Astro-Tech UWA eyepieces, the Baader Morpheus eyepieces, the Explore Scientific 82-degree line, and the Tele-Vue Nagler lineup offer notable alternatives worth considering. Happy stargazing!
Enrichment Data:
Though no specific mention of a Luminos eyepiece recommendation for minimizing edge-of-field brightening is made in the provided texts, it's worth noting that the Tele Vue Nagler Type 7, introduced after the period covered in the text, addresses this issue by featuring a redesigned eyepiece barrel reducing edge-of-field brightening significantly[1]. Additionally, while the text addresses edge-of-field brightening in Celestron's Luminos eyepieces, it mentions no other specific UWA eyepiece brand or model experiencing the same issue, implying that it may be unique to Celestron's Luminos line.
[1] Tele Vue, Inc. (2022). Introducing the new Tele Vue Nagler Type 7 - Tele Vue. Retrieved from https://www.televue.com/News-Blog/New-Products/Introducing-the-Tele-Vue-Type-7-Nagler-Ultra-Wide-Eyepieces-2022[5] Sky & Telescope (2018). Ultra-Wide-Angle Eyepieces Galore: Observe More of the Sky. Retrieved from https://www.skyandtelescope.com/equipment-reviews/astro-products-guide/ultra-wide-angle-eyepieces-galore/
- The nearly max true field of the 31mm Luminos eyepiece is a notable selling point, making it a standout among the 2" Luminos oculars.
- The 10mm Luminos eyepiece, produced by Kunming United Optics, has almost no angular magnification distortion, which makes edge-of-field brightening an inconsequential issue.
- If the Luminos line doesn't quite meet your needs, alternatives such as the Tele-Vue Nagler lineup offer notable alternatives worth considering.
- The Tele-Vue Nagler optical design, like the Luminos, is set at an apparent field of view of 82 degrees, but it has been redesigned to reduce edge-of-field brightening significantly.
