NotebookLM Experiment: Fact-Check! "Evolution of Swift Audubon Binoculars - Featherweight to 804 Redesign"

 

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Technical Analysis and Historical Review of the Swift Audubon Model 804 Binoculars

Source guide

The source provides a comprehensive technical analysis and historical review of the Swift Audubon Model 804 binoculars, an iconic wide-angle Porro prism instrument designed for serious ornithology between 1960 and 1999. Its reputation stems from an intentional user-driven design that resulted in the unconventional 8.5x44 configuration, celebrated for achieving an optimal balance between stable, hand-held viewing and ample light transmission. While the instrument is renowned for its outstanding central sharpness and expansive 8.2° True Field of View, which creates a celebrated "spacewalk experience," this wide-field advantage is achieved at the cost of pronounced edge softness and field curvature. The source also details the collectibility of the Japanese-made models and warns prospective vintage buyers that the classic 804 models are susceptible to internal contamination due to the lack of modern sealing and purging.

Technical Analysis and Historical Review of the Swift Audubon Model 804 Binoculars

I. Genesis of a Legend: Historical Context and Design Philosophy

The Swift Audubon Model 804 represents one of the most significant and enduring wide-angle Porro prism binoculars ever produced. Its reputation stems not from accidental success but from an intentional design process engineered to meet the stringent demands of serious ornithology during the mid-20th century. The longevity of the Model 804 series firmly established it as a benchmark in high-performance field optics.

I.A. The Swift Optics Legacy and the Birth of the Audubon Line

The development of the 8.5x44 configuration was a highly calculated decision. The research indicates that the specifications for the original Swift Audubon binoculars were derived directly from a survey conducted among the world's leading ornithologists.[1] This user-driven design led to the selection of the unconventional 8.5x magnification, which is frequently cited as the optimal "sweet spot" for prolonged, steady hand-held viewing.[2] This power provides adequate magnification for identification while statistically minimizing the effects of natural hand tremor, a magnification leverage issue common in 10x instruments.[3, 4]

The optical configuration combines this stability with a substantial 44mm objective lens, which yields an ample 5.2mm exit pupil ($44/8.5\approx 5.2$).[3] This optimized ratio maximizes light transmission to the human eye, ensuring bright images even in the challenging low-light conditions often encountered during deep woods birding, solidifying the model's intent as a specialized tool for demanding birdwatchers.[5] The history of the classic Model 804 spanned approximately 40 years, running from 1960 to 1999, cementing its status as an iconic instrument across multiple generations of observers.[6]

I.B. Manufacturing Provenance: The Era of Japanese Excellence

The enduring quality and collector desirability of the 804 series are inextricably linked to its Japanese manufacturing provenance.[7, 8] These instruments were produced during an era recognized for exceptional precision and robustness in Japanese optical manufacturing.

Specific variants are highly valued due to their factory origin. For example, some early examples are strongly associated with Tamron, an optical house renowned for producing some of the finest Japanese wide-angle binoculars of that period.[9] This association is sometimes confirmed by the presence of the Tamron symbol found on the hinge cover of early models, dating them potentially to 1959–1960.[10]

Further evidence of early production comes from factory codes and unique markings. An exceptionally clean, early model with the serial number 12-62242, for instance, has been identified as an early 1960s JE47 factory piece (Japan Export Optical Inspection mark plus assembler code).[11] Additionally, the stamping "Ultrar RLE 8.5x44.0" is noted as a rare feature, appearing only on very early production batches before 1965, serving as a critical marker for dating and confirming collectibility for vintage enthusiasts.[11] The 804's value is therefore intrinsically tied to this vintage construction, which many collectors believe prioritized robust, precision-machined components over the mass-produced ergonomic trends of later designs.

I.C. Evolution of the Model 804 Body: Variants and Revisions

Throughout its four-decade lifespan, the 804 underwent several major design adjustments, making identification of specific vintages essential for collectors.[6]

Although no specific "Mark I Audubons" were officially designated, a Mark I lineup meeting different engineering criteria existed concurrently with the Audubon line. The highly regarded Mark II models, which date back to the early 1960s, were Swift's "Premium Quality" series, defined by the core 5-element ocular system and three other specific quality construction characteristics.[6]

Later revisions included the 804R, where the "R" suffix explicitly stands for "revised".[6] Subtle body variations exist across these versions, such as the triangle marking on the prism plate sometimes displaying "Wide Field" and sometimes "Mark II".[12] Mechanical evolution is also visible in the focusing mechanisms. The earliest models employed a silver ribbed metal focusing wheel situated directly between the hinges. Subsequent designs relocated the focus knob to a position between the hinge and the bridge, or eventually incorporated rubberized features seen in later optics.[6]

A short-lived but important transitional variant, produced around 1983–1984, featured distinctive blue or gold ribbons on the left cover plate.[6] These "ribbon models" maintained the original optical core but incorporated certain features later consolidated into the smaller, subsequent 804R design.

II. The Optical Engine: Deep Dive into Technical Specifications

The optical performance of the Swift Audubon 8.5x44 Porro prism is predicated on a set of specifications deliberately chosen to maximize light grasp, stability, and field of view for field observers.

II.A. Defining Optical Metrics (8.5x44 Porro Prism)

The core structure of the 804 relies on the Porro prism design, which inherently grants superior depth of view and contrast compared to roof prism equivalents, due to its simple, non-folded light path.[3] Key optical measurements confirm its high-performance profile:

• Magnification and Aperture: 8.5x magnification combined with a 44mm objective lens.[3, 13]

• Exit Pupil and Twilight Factor: The resulting 5.2 mm exit pupil [3] ensures that the binoculars deliver ample light transmission to the eye, especially under twilight conditions. The calculated Twilight Factor of 19.34 further confirms the instrument's strong performance capabilities in transitional lighting.[3]

• Ocular System: The foundation of the 804's fame is its advanced optical architecture, which features a 5-lens ocular system paired with high-quality BaK4 prisms.[1, 3] The complex five-element eyepiece is crucial; it provides the technical necessary correction to achieve an extreme wide-angle view while preserving exceptional center sharpness.[11]

II.B. The Wide Field Advantage

The Model 804 is legendary for its expansive field of view, an attribute particularly valued by birders for rapidly acquiring and tracking subjects.

The True Field of View (TFOV) is an expansive 8.2°.[2, 3] This translates to a measurement of 430 feet at 1,000 yards, or 143 meters at 1,000 meters.[1, 3] For its era, this field measurement was exceptional, famously beating competitors in the premium birding segment, such as the Swarovski 8.5x42 EL, which offered 390 feet.[3]

This vast field yields an Apparent Field of View (AFOV) of approximately 69.7°.[3] This AFOV pushes the limit of what can be considered a truly wide-angle experience, creating what enthusiasts often describe as a "spacewalk experience" when used for sweeping the night sky.[2] This expansive perspective covers 90% more area of the sky than a typical 6° TFOV binocular would show.[2]

II.C. Physical and Mechanical Characteristics

The instrument’s physical design reflects its intended use as a dedicated field optic. The weight is generally around 24 oz (680g) [3], though some early models may reach up to 800g.[8] This relatively light mass for a full-sized 44mm Porro prism enhances portability. Construction was typically robust, utilizing materials like magnesium for the body to reduce weight in later, more modern iterations.[1]

Focusing capabilities are well-suited for nature observation, with a close focus distance of 10.0 feet (3m).[3] Dioptric adjustments are located on the traditional right eyepiece.[8] Eye relief (ER) is listed between 16mm and 17mm.[3, 8] While this range is typically considered sufficient for eyeglass wearers, user feedback indicates that some eyeglass users may still struggle to see the entire wide field of view.[14] The eyecups on earlier 804 models were often simple, stiff, fold-down rubber cups [2], a key ergonomic difference from the later 820 series which introduced the "pop and lock" eyecups for enhanced comfort.[1]

A critical consideration for vintage acquisition is weather resistance. The classic 804 models were generally not nitrogen-purged or fully sealed, a factor that renders them susceptible to internal moisture, fungus, and fogging.[15, 16] Although some variants were physically marked "waterproof" [8], this designation often implied basic rain resistance rather than the full sealing and inert gas purging found in the modern, fully Waterproof, Fogproof, and Shockproof 820T/ED successors.[1] The lack of modern sealing serves as the primary mechanism for internal degradation in many surviving vintage units.

II.D. Lens Coating Variations (MC vs. FMC)

The lifespan of the 804 spanned decades of anti-reflection coating advancements, leading to performance variations across vintages. Models varied from simple coated (C) to Multi-Coated (MC) to Fully Multi-Coated (FMC) optics.[13, 17] Superior lens coatings are essential for maximizing light transmission and reducing external reflections.[18]

Swift incorporated a prism coating technology called Cold Fusion Technology (CFT).[3] Users noted that the coating recipe sometimes impacted color fidelity. For instance, the Multi-Coated (MC) 804 was praised for providing the "easiest view," but was noted for imparting a slight yellow tint on overcast days.[17] This chromatic shift was likely a deliberate engineering choice in certain batches, designed to increase contrast when viewing targets in the shaded environments of deep forests, but it resulted in a view that observers found less color-accurate than some contemporaries.[19] This variance in coating history means that the visual experience, particularly concerning color accuracy, can differ significantly between production runs.

Table 1: Swift Audubon 804/804R Classic Porro Prism Technical Profile

Specification	Swift 804/804R (Classic Porro)	Source Reference	Design Implication
Magnification x Objective	8.5x44mm	[3, 13]	Optimal hand-held stability/light grasp balance.
Prism Type & Material	Porro Prism, BaK4	[1, 3]	Key to wide FOV and superior depth perception.
Optical System	5-Element Ocular	[1, 3]	Critical for achieving the expansive AFOV.
True Field of View (TFOV)	8.2° (430 ft @ 1000 yds/143m @ 1000m)	[3]	Wide-field dominance over contemporaries.
Apparent Field of View (AFOV)	$\sim 69.7^{\circ }$ (Approx. $70^{\circ }$)	[2, 3]	The "spacewalk" experience benchmark.
Exit Pupil	5.2 mm	[3]	Excellent low-light performance potential.
Eye Relief (Reported/Usable)	16mm - 17mm (Advertised)	[3, 8]	May be tight for some eyeglass users.[14]
Close Focus Distance	10.0 ft / 3m	[3]	Adequate for close-range birding.
Weight (Approx.)	24 oz / 680g (Varies up to 800g)	[3, 8]	Lightweight for a 44mm full-size Porro.
Weatherproofing	Non-Waterproof/Non-Fogproof	[1, 15]	Vulnerable to internal contamination; use restricted to dry conditions.

III. Performance Assessment: Clarity, Contrast, and Field Characteristics

The optical signature of the Model 804 is characterized by a deliberate performance trade-off, prioritizing immense field width and central fidelity at the expense of edge-to-edge flatness.

III.A. Center Sharpness and Resolving Power

The 804 is recognized for its "outstanding center sharpness" [2], providing "clear and detailed views of distant objects".[13] The sophisticated 5-element eyepiece, coupled with high-quality glass, ensures that the instrument achieves a level of resolving power usually unexpected for its size class.[2]

The exceptional resolution is particularly evident in astronomical observations, where stars focus down to "true pinpoints".[2] The resolving capability is such that the instrument can cleanly split tight double stars, such as 59 Andromedae (16.5 arc seconds separation), demonstrating a clean split with ample black space between the components.[2] The image generated through the center is consistently reported as "bright and incredibly crisp".[3]

III.B. Off-Axis Performance: The Wide-Field Compromise

The design choice to push the Apparent Field of View (AFOV) to nearly $70^{\circ }$ resulted in an inherent optical compromise: significant softness and distortion at the outer edge of the view.[2] This blurring is so pronounced that users have reported mistaking their specific sample for a defect ("a lemon") until realizing it is a characteristic shared across the 804 series.[2]

This edge degradation, caused by uncorrected field curvature and coma, manifests as objects stretching or distorting (stars looking like "seagulls").[2] In practical terms, astronomical observers noted that bright objects like the Full Moon must be positioned at least two diameters away from the field edge to maintain acceptable sharpness.[2] This performance trade-off confirms that the 804 was engineered specifically as a pure birding instrument, where maximizing the instantaneous, immersive field of view for target acquisition and prioritizing central detail (the "sweet spot") were deemed far more critical than achieving edge-to-edge flatness of field.

III.C. Build Quality and Durability Assessment

The overall physical construction of the Swift 804 is consistently rated as excellent.[2] Many vintage examples surviving today, despite their age, are described as durable and resilient.[20] The older 804 models are often praised for feeling more solid in the hand compared to the later, more ergonomic, and rubber-armored 820 series.[17] Users reported no structural issues over a decade of use with certain samples.[2]

However, some minor functional and accessory deficiencies are noted. Some models display noticeable, though usually unobjectionable, prism clipping, which suggests slight vignetting or imperfect alignment of the light path.[4] Furthermore, the original accessories were often not commensurate with the high quality of the optics. Specifically, the soft padded case sometimes supplied with the 804 was considered inferior to the hard cases of other Swift models, and the objective lens caps were frequently too loose, easily slipping off the barrels.[2] Mechanically, a common age-related failure point is the helical eyecup mechanism, which can lose friction over time and slip down when not held firmly against the eye socket.[4]

III.D. Application-Specific Reviews (Birding and Astronomy)

The wide-angle philosophy of the 804 proved highly effective in its intended domain. For birding, the vast field of view makes the binoculars outstanding for deep woods use, simplifying target acquisition and allowing the good depth of field to help observers penetrate complex brush and foliage.[14] The model’s effectiveness led to its official recommendation by the American Birding Association (ABA).[5]

For amateur astronomy, the 8.5x magnification is a favored power for hand-held scanning, and the 70° AFOV provides a spectacular and immersive visual experience.[2] Enthusiasts specifically celebrate the 804 for wide-field sweeping of the Milky Way, noting the truly unique "spacewalk experience" it provides.[2, 4]

IV. Comparison and Legacy: The 804 in Context

The stature of the Swift 804 is best understood by analyzing its relationship with its primary contemporaries and its modern successors. This comparison highlights competing design philosophies within the vintage high-performance birding market.

IV.A. Rivalry with the Bausch & Lomb Custom (8x36)

The Swift Audubon 8.5x44 and the Bausch & Lomb Custom 8x36 were two of the era's most significant Porro prisms, both enjoying Audubon Society endorsement.[21, 22] A direct comparison between a Swift 804R and the B&L Custom 8x36 revealed distinct differences in optical signature.[19]

Despite the 804R having a larger objective lens (44mm vs. 36mm) and a larger theoretical exit pupil (5.2mm vs. 4.5mm [23]), the B&L Custom was subjectively judged to be brighter and significantly superior in color accuracy and vibrancy (or 'pop') during terrestrial viewing under warm "golden hour" light.[19] The 804R was noted for rendering the golden light in a duller, washed-out fashion, closer to a "cold LED 5000k bulb".[19]

Crucially, the B&L Custom also exhibited better clarity and flatness toward the edges of the field than the 804R.[19] For astronomy, the B&L Custom was favored due to the superior precision of its focusing mechanism.[19] The B&L Custom also offered slightly better eye relief at 19mm [23], compared to the 804's 16–17mm.[8]

This competitive analysis reveals that the vintage high-end market was split between two primary camps: the Swift camp, which pursued maximum AFOV and central sharpness, and the B&L camp, which emphasized color neutrality, focusing precision, and better edge-to-edge flatness, often achieved by accepting a slightly narrower field of view.

IV.B. Successors: The Modern 820 and 820ED Series

Swift recognized the need to update the aging 804 design to compete with modern optics, leading to the development of the 820T and 820ED models. These successors retain the renowned 8.5x44 Porro configuration and the 5-lens ocular system, but integrate several key technological and ergonomic advancements.[1]

IV.B.1. The ED Glass Advantage

The most significant optical upgrade is the introduction of Extra-low Dispersion (ED) glass in the 820ED model. ED glass provides precise color definition, dramatically reducing chromatic aberration (CA), resulting in more vibrant colors and superior resolution compared to the non-ED 804.[1, 17] This addresses the color accuracy issues sometimes observed in the older multi-coated 804 variants.[19]

IV.B.2. Ergonomic and Environmental Upgrades

The 820 series features a transition to rubber armoring for improved durability and shock absorption, as well as a fully sealed and purged body, making them Waterproof, Fogproof, and Shockproof.[1] They also introduced the "pop and lock" eyecups, improving comfort and utility for users with and without eyeglasses.[1]

IV.B.3. Performance Trade-offs

While the 820ED provides superior CA correction and weather resilience, some vintage enthusiasts retain a preference for the older build. The 804 is consistently described as feeling more structurally "solid" than its successor.[17] Furthermore, some users noted that even the ED predecessor (the 804 ED variant) suffered from a "narrow sweet spot," making simultaneous sharp focus difficult even across small star groups.[14] The fact that the classic 804, with its simple coatings and robust construction, often still outperforms modern, mid-range roof prism binoculars (due to the inherent advantages of Porro prisms over roof prisms concerning phase shift and light loss) validates the high optical execution of the original design.[11]

Table 2: Comparative Analysis of the Swift Audubon 8.5x44 and Key Rivals

Model	Swift 804 (Vintage)	Bausch & Lomb Custom (8x36)	Swift 820ED (Modern Successor)
Magnification x Objective	8.5x44	8x36	8.5x44
Prism Type	Porro (BaK4)	Porro (BaK4, open hinge)	Porro (BaK4)
True Field of View (TFOV)	8.2° (430 ft) [3]	N/A (Likely Narrower)	8.2° (430 ft) [1]
Center Resolution	Exceptional [2]	Excellent [19]	Excellent (Enhanced by ED) [17]
Edge Performance	Significant Field Curvature/Softness [2]	Better Edge Sharpness/Flatness [19]	Improved, but still Porro traits [14]
Color Rendition	Can be "Washed out"/Yellow Tint (Varies by coating) [17, 19]	Excellent Color Pop/Accuracy [19]	Vibrant, Low CA (due to ED glass) [1, 17]
Weatherproofing	None/Rainproof only [8]	None/Rainproof	Waterproof/Fogproof/Shockproof [1]
Eye Relief	16-17mm [8]	19mm [23]	14.5mm (Advertised) [14]
Collectibility/Price (Used)	High, $\$85–\$200$ [24]	High, Niche Collector Item [21, 25]	Lower (Still produced)

V. Acquisition, Maintenance, and Collector Market

Owning a vintage Swift Audubon 804 requires an understanding of its mechanical vulnerabilities and the dynamics of the specialized collector market.

V.A. Common Issues and Maintenance

Given that the original 804 models lacked the sealing and nitrogen purging of modern optics, internal contamination is the primary risk factor. Internal moisture accumulation can lead to condensation residue, fungus, or dust inside the optical path.[15, 16]

Miscollimation, resulting in an "obvious double image," is also a frequent issue in used Porro prisms, typically caused by physical shock or neglect.[16] Correcting this requires accessing the internal collimation screws, often hidden under the leatherette or prism cover plates.[16, 26]

Do-it-yourself repair of the 804 is technically challenging. Internal components, specifically the prism block assembly, must be removed from the eyepiece side. Technicians have noted difficulty removing this block due to clearance issues with the neck strap fitting, requiring the assembly to be lifted and tilted at a precise angle.[26] Furthermore, successful recollimation after cleaning is a delicate process, demanding careful re-indexing of the eyepieces and adjustment of the internal prisms.[26] Because of these complexities, a buyer purchasing a neglected unit must anticipate potential professional servicing costs, which can substantially exceed the initial acquisition price.

V.B. Collectibility and Secondary Market Valuation

The Swift Audubon 8.5x44 Model 804 remains an iconic and highly desirable piece among optics collectors ("binoholics").[10] Its well-documented history across specialized forums ensures a consistent demand.[10]

Secondary market valuation is heavily dependent on condition. Prices for used 804 models show significant variation:

• Samples requiring work or exhibiting cosmetic flaws may sell for approximately $85.00.[24]

• Units described as being in "very nice condition" and including original accessories (case, lens covers) typically fetch higher prices, ranging from $124.00 to $199.99.[13, 24, 27]

Premium pricing is reserved for early, high-quality Japanese-built examples, particularly those linked to manufacturers like Tamron.[9, 11] Rare, well-preserved versions (such as a 1982 Extra Wide Angle model) command the higher end of the range.[24, 27] The purchase of an 804 is frequently viewed as an investment in a restoration project, where the collector recognizes the underlying optical quality of the assembly, despite superficial or mechanical flaws stemming from decades of use and the lack of modern weatherproofing.[10]

VI. Conclusions

The Swift Audubon Model 804 8.5x44 Porro prism binocular is rightfully regarded as a landmark achievement in vintage sports optics. Its enduring legacy is a product of its revolutionary design intent: an instrument purpose-built for ornithology, prioritizing maximum immersive field of view and outstanding central resolving power (achieved through the 5-element ocular system) above all other metrics.

The optical performance, characterized by extreme central sharpness and a class-leading 8.2° TFOV, validates the Porro design philosophy for field observation. However, its defining characteristic—the expansive field—simultaneously dictated its primary optical flaw: pronounced field curvature and edge softness.

For the modern collector, the Model 804 offers unparalleled optical immersion at a relatively accessible price point. However, prospective buyers must recognize that the acquisition of a vintage 804 is contingent upon accepting the risks associated with non-weatherproof optics, including potential miscollimation and internal contamination. While newer models like the 820ED offer superior chromatic correction, rubber armoring, and sealing, the classic 804 remains distinct for its historical significance, unique optical signature, and superior perception of build solidity, making it a highly desirable piece for both serious birders and wide-field astronomy enthusiasts operating in dry conditions.

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1. Swift Premier High Performance Binoculars - Swift Sport Optics, http://www.swift-sportoptics.com/binoculars.html

2. Swift Audubon 8.5x44 model 804 - Under 50mm - Cloudy Nights, https://www.cloudynights.com/articles/user-reviews/binoculars/under-50mm/swift-audubon-85x44-model-804-r1584/

3. Swift Audubon Porro Prism 8.5x44 Binoculars Review, https://www.bestbinocularsreviews.com/Swift8.5x44AudubonPorroPrism-29.htm

4. Swift Audubon 8.5x44 model 804 - Discussion of CN Articles, Reviews, and Reports, https://www.cloudynights.com/topic/101322-swift-audubon-85x44-model-804/

5. Swift Audubon 8.5x44 – ABA Approved Binoculars Every Birder Should Know! - YouTube, https://www.youtube.com/watch?v=aM0OWOkWS_U

6. Historical Review of Swift 804 Audubon Binoculars | BirdForum, https://www.birdforum.net/threads/historical-review-of-swift-804-audubon-binoculars.42944/

7. Swift Audubon 8.5x44 Model 804R Wide Binoculars Multi-Coated Optics Japan Read - eBay, https://www.ebay.com/itm/376350054097

8. Swift Audubon ED 8.5x44 - East of England Binoculars, http://www.eebc.co.uk/productDisplay.aspx?productid=672

9. my new Swift Audubon MK1 8.5X44 model 804 binoculars - Cloudy Nights, https://www.cloudynights.com/topic/964690-my-new-swift-audubon-mk1-85x44-model-804-binoculars/

10. The Swift Audubon - Binoculars - Cloudy Nights, https://www.cloudynights.com/forums/topic/809572-the-swift-audubon/

11. my new Swift Audubon MK1 8.5X44 model 804 binoculars - Cloudy Nights, https://www.cloudynights.com/forums/topic/964689-my-new-swift-audubon-mk1-85x44-model-804-binoculars/

12. Swift Audubon Mark II Model 804R 8.5x44 - Binoculars - Cloudy Nights, https://www.cloudynights.com/forums/topic/723159-swift-audubon-mark-ii-model-804r-85x44/

13. Swift Audubon 8.5x44 Model 804 Binoculars w/ Case Multi-Coated Optics | eBay, https://www.ebay.com/itm/286733187757

14. Any swift audubon 8.5x44ED user out there? - Binoculars - Cloudy Nights, https://www.cloudynights.com/topic/119192-any-swift-audubon-85x44ed-user-out-there/

15. Anyone know how to clean fogged binoculars??? : r/Hunting - Reddit, https://www.reddit.com/r/Hunting/comments/3vhill/anyone_know_how_to_clean_fogged_binoculars/

16. Swift Audubon 804 HR/5 sn95*****restoration project . | BirdForum, https://www.birdforum.net/threads/swift-audubon-804-hr-5-sn95-restoration-project.435021/

17. Swift Audobon 804 vs newer ED - Binoculars - Cloudy Nights, https://www.cloudynights.com/forums/topic/213936-swift-audobon-804-vs-newer-ed/

18. Fully coated lens coatings Vs Fully multi-coated optics. What is the difference. - YouTube, https://www.youtube.com/watch?v=5BVgVGxQLlw

19. No "Wow" from new Swift 804R. What's wrong? - Binoculars - Cloudy Nights, https://www.cloudynights.com/forums/topic/833205-no-wow-from-new-swift-804r-whats-wrong/

20. 1982 Swift Audubon Model 804 Binoculars EXTRA WIDE ANGLE, 8.5x44. NICE & RARE, https://www.ebay.com/itm/205837590383

21. Binoculars & Monoculars 8-9x Maximum Magnification for sale | eBay, https://www.ebay.com/b/Binoculars-Monoculars-8-9x-Maximum-Magnification/83880/bn_7339230

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26. Repair Swift Audobon #804, cannot remove prism plate due to screw for neck strap, https://www.cloudynights.com/topic/848111-repair-swift-audobon-804-cannot-remove-prism-plate-due-to-screw-for-neck-strap/

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