Vintage-Fernrohre aus den 1980er-Jahren, wie das hier abgebildete Celestron-Modell, wiesen oft deutlich größere Prisma-Gehäuse im Vergleich zu ihren modernen Entsprechungen auf. Dieses Paar von 20x80-Fernrohren zeigt, dass sich trotz ähnlicher Gesamtabmessungen mit seinem zeitgenössischen Gegenstück die ältere Bauweise durch voluminösere Gehäuse auszeichnet, um die optischen Komponenten zu beherbergen. Der physische Vergleich unterstreicht, wie sich die Größen der Prisma-Gehäuse im Laufe der Zeit verändert haben, selbst wenn grundlegende Spezifikationen wie Vergrößerung und Objektivdurchmesser konstant blieben.
Can you recommend a compact pair of binoculars suitable for indoor and outdoor concerts, plays, and sports? I’m currently trying the Nikon Travelite but would prefer something a bit smaller.
Larger prisms allow more light to pass through, resulting in a brighter view.
Why do newer binoculars tend to have smaller prisms? It’s rare to see the large round housings now.
Older binoculars often use porro prisms, which are larger than modern roof prisms. Many people today prioritize portability over performance. For example, most birders use 8×42 binoculars for their balance of size and function. If cost and weight were no concern, larger models like 8×100 would allow extended use from dawn until late at night.
No, you wouldn’t benefit from an 8×100 binocular. It has a 12.5mm exit pupil, but even a teenager’s pupils only dilate to about 7mm, so the extra light can’t enter the eye. For someone middle-aged with pupils around 5mm, the largest practical binocular would be an 8×40.
Does this also apply to Galilean optics? I have a pair of 2.1×42 binoculars for stargazing, which should give a 20mm exit pupil, but they still help me spot stars that aren’t visible to the naked eye.
No, that doesn’t apply here. Galilean optics are quite different from prismatic optics. I believe, though I may be mistaken, that Galilean optics don’t have a true exit pupil. Essentially, you move your eye within the image to see the full field of view. This isn’t a subject I know much about, except to note that familiar binocular concepts don’t necessarily apply. Hopefully, another regular in this subreddit who knows the topic can explain why your low-power Galilean binoculars bypass the usual rules of thumb regarding exit pupil.
Many vintage binoculars feature a wide or ultra-wide field of view, which requires large prisms to support the correspondingly large field stop. These big prisms necessitate larger housings. Modern binoculars generally have narrower fields of view, allowing for smaller prisms and housings.
Additionally, prisms must be large enough to avoid truncating the light cone, which depends on factors like objective size and focal ratio. If prisms are too small, they restrict the light cone, reducing the effective aperture. For example, a 20×80 binocular might function as a 20×70 if the prisms are undersized. Using smaller prisms cuts manufacturing costs and reduces size and weight, but this practice can compromise performance. Many older binoculars were designed to function at their full claimed aperture, with appropriately sized prisms to prevent light loss.
Marketing perception may also have played a role. High-quality models like the Bausch & Lomb from the mid-20th century had distinctive large, rounded prism covers, a design that other manufacturers often emulated.
My vintage 7×35 11.5-degree binoculars have the same large round housings, so that makes sense. Thanks for the explanation.
Manufacturing technology has evolved significantly. Older binoculars like the 1980s Celestron Giant featured metal bodies shaped by the metal-forming techniques of that era. Modern binoculars, including recent Celestron models, often use polycarbonate bodies. Advances in plastic molding now allow for more complex shapes that were impractical decades ago, enabling smaller, more compact, and cost-effective designs.
Design philosophy has also shifted. Traditional binoculars were built for maintenance and repair, with large, flat prism covers secured by screws and removable ocular housings. In contrast, many modern binoculars are designed as disposable products. Their prism housings are tightly wrapped around the prisms since they are not intended to be disassembled, leading to a throwaway approach when issues arise.
Thank you for sharing your knowledge.
Older binoculars often had larger prism housings because the prisms themselves were bigger. The main advantage was that larger prisms could gather more light, which improved image brightness, especially in low-light conditions.
I’ve never seen an 8×40 with an 11.5° field of view and wonder if you might be referring to a 7×35 at 11.5°. At 8x magnification, the widest field of view I’m aware of is a claimed 10°, and I own one that I like a lot. Yes, my 10° 8×40 has very large prisms. If you don’t mind sharing, what is the make and model of the 8×40 with an 11.5° field? It would set a new record.
I say “claimed” because vintage ultra-wide binoculars often measure slightly narrower than advertised. This was possible because the Japanese Telescope Inspection Institute, which enforced technical standards for export and applied silver or gold oval stickers to certify quality, allowed a tolerance on the stated field of view.
At 7x magnification, many vintage Japanese binoculars have an 11° field, and some are wider. I have a Montgomery Wards model at 11.8°, if I recall correctly, and a Swift 7×35 that claims well over 12°. However, the Swift isn’t particularly good and would benefit from a narrower field.
You’re right. I didn’t have them on hand to check and confused them with another pair (B&L 8×40). I’ve updated my comment.
Older prisms likely had a lower refractive index. Similar to eyeglasses, higher refractive index materials can achieve the same optical power in a thinner form than those with a lower index.
Older binoculars often have larger prism housings because they were designed to accommodate Bak4 prisms, which have been in use for a long time. For example, all three of my World War II-era 7×50 binoculars feature Bak4 prisms.
Porro prism binoculars, with their larger offset eyepieces, generally provide better image quality for the price compared to the more compact roof prism design. However, they are heavier and bulkier. Most consumers prioritize portability over optical performance, which is why few manufacturers still produce porro prism models.