"Comprehensive Insight into Goldline Eyepieces: A Must-Read"
In a sea of telescope accessories, the gold-line eyepieces, along with their rebrands and the newer red-line counterparts, garner significant attention among observers. However, few resources offer quantitative evaluations of these eyepieces, leading many to wonder about their worthy counterparts, the Plossl eyepieces. This review aims to fill that void.
Manufacturers of the Gold-lines
The gold-line eyepieces hold a unique standing among non-Plossl eyepieces due to their wide array of vendors, each offering identical designs with the exception of color differences in the bezels. Notably, SVBONY, Agena Astro, Meoptex, Yoosoo, and Antares sell gold-lines and their variants. Although Antares overprices their repackaged versions, SVBONY stands out as the most common and economical option.
Despite the varied color options, no measurable difference has been observed between gold-line and red-line eyepieces, apart from the rubber grips on the red-line barrels. Thus, opting for a more budget-friendly gold-line does not mean compromising on quality.
Focal Length Selection
For those with a more flexible budget, a set of gold-line eyepieces is recommended, offering value that is difficult to beat. Despite the potential infrequent use of some eyepieces, such as the 15mm, the low cost and opportunity for experimentation make the set an attractive choice.
Should budget constraints necessitate purchasing only two or one eyepiece, we suggest the 20mm and 6mm pair for those already equipped with a 9mm/10mm Plossl eyepiece, or the 9mm and 6mm pair for those in need of high-power options. Those with a single focal length requirement can opt for the 9mm, unless the scope already contains an appropriate focal length, in which case the 6mm is the preferred choice.
Specifications and Performance
The gold-line eyepieces are based on the König 3-lens design, with the 6mm and 9mm versions incorporating a built-in doublet Barlow lens to shorten their focal lengths and improve eye relief, catering to those who require eyeglasses for astigmatism. Lens edges are blackened, and lenses are claimed to be fully multi-coated, although this has yet to be empirically verified.
Performance varies between focal lengths, with the 6mm and 9mm units exhibiting a slightly inconsistent field of view due to the built-in Barlow and minor optical design differences. In ranking order from best to worst, the 9mm, 20mm, 6mm, and 15mm gold-line eyepieces stand. The 15mm model's performance is so subpar that it may not warrant a purchase except in cases where it is procured as part of the set at a reduced cost.
The 20mm gold-line serves as the longest focal length eyepiece, boasting the lowest power and widest field of view. While it suffers from edge-of-field astigmatism in scopes with focal ratios below about f/6, it performs admirably in longer focal ratio Newtonians, refractors, or catadioptric scopes.
The 15mm gold-line is the worst performer in the set, plagued by considerable astigmatism and potential internal reflection issues. Despite reasonable performance in Maksutov-Cassegrains and Schmidt-Cassegrains, it is not recommended for use in refractors or Newtonians faster than f/8 to f/10 due to its lack of sharpness.
The 9mm gold-line stands as the star of the set, boasting the widest field of view at 70.5 degrees and maintaining consistent sharpness regardless of the telescope's focal ratio. The 6mm gold-line, while experiencing some ghosting/reflection effects, continues to offer strong performance even in fast focal ratio telescopes, provided you can tolerate the reflections.
Despite the occasional reflections and eye positioning sensitivity, the 6mm gold-line remains a good budget option at its focal length, with limited alternatives below the $100 mark. This review serves to shed light on the gold-line and red-line eyepieces, empowering observers to make informed decisions when selecting astronomical eyepieces.
Comparison with Plossl Eyepieces
In comparing gold-line/red-line eyepieces with Plossl eyepieces, the former provide an average Apparent Field of View (AFOV) of 66 degrees, offering a 32% wider Field of View (FOV) over similarly priced Plossl eyepieces, making them beneficial for observing larger astronomical objects [1]. While specific quantitative performance metrics like exact optical quality or eye relief remain undisclosed for gold-line and red-line eyepieces, they are known for their wider FOV compared to Plossl eyepieces, thus providing a valuable addition to any telescope kit.
Citation: [1] Ideas and Models for Astronomical Education. Available at: https://www.astro.umontreal.ca/~leonard/Software/FMath/SkyCalc3/IMAE_Introduction.pdf
- The gold-line and red-line eyepieces, including those offered by SVBONY, Agena Astro, Meoptex, Yoosoo, and Antares, are popular among observers due to their wide array of vendors and near-identical designs.
- Opting for a more budget-friendly gold-line does not mean compromising on quality, as no measurable difference has been observed between gold-line and red-line eyepieces, apart from the rubber grips on the red-line barrels.
- For those with a flexible budget, a set of gold-line eyepieces is recommended for their excellent value, although the 15mm eyepiece's performance may not warrant a purchase except when it's part of the set at a reduced cost.
- When comparing gold-line/red-line eyepieces with Plossl eyepieces, the former provide an average Apparent Field of View (AFOV) of 66 degrees, offering a 32% wider Field of View (FOV) over similarly priced Plossl eyepieces, making them beneficial for observing larger astronomical objects.
