The Sightron Objective Stop Ring for 50mm Riflescopes (Model: SI-70016) is a precision screw-in optical accessory engineered to restrict the front lens aperture on compatible riflescopes. Designed to thread directly into the front objective threads of Sightron 50mm optics—or stack with a factory 50mm sunshade—the stop ring functions as an optical diaphragm. By stopping down the entrance pupil, it increases the system's effective focal ratio, which significantly deepens the optical depth of field while mitigating optical distortion caused by barrel heat and ground mirage under bright daytime conditions.

Key Features

• Aperture Restriction: Functions as a mechanical diaphragm stop over the objective assembly, narrowing the entrance pupil to increase depth of focus across varied target distances.
• Mirage Management: Reduces the visual impact of radiant ground shimmer and barrel heat, allowing precision shooters to retain reticle sharpness and accurately gauge wind via mirage lines.
• Thread-In Integration: Threads straight into standard Sightron 50mm front objective lens assemblies, operating either standalone or joined directly to compatible 50mm sunshades.
• Passive Mechanical Build: Functions entirely without batteries or internal electronic circuits, providing centrefire-rated recoil resilience when threaded securely.

Specifications

• Model / SKU: SI-70016 (70016)
• Product Type: Riflescope objective stop ring
• Compatible Objective Size: 50mm
• Compatible Series: Sightron riflescopes with 50mm objective bells (including 50mm models across SIII, SV, and S-TAC series)
• Operating Mechanism: Passive optical aperture restriction
• Power Requirements: None

Who is the Sightron Objective Stop Ring For 50mm Riflescopes for?

• Long-range precision rifle competitors — controls radiant barrel mirage and heavy ground shimmer during high-heat matches by stopping down the light path on compatible 50mm riflescopes to preserve reticle and target clarity.
• F-Class and benchrest target shooters — sharpens the overall depth of field across long target distances and aids in reading wind-driven heat lines through a 50mm objective lens stop ring.
• Varmint hunters — deepens focus across open paddocks during intense, bright daytime sunlight when targeting small pests through a 50mm riflescope.

Less suitable for: Low-light hunting at dawn, dusk, or under heavy overcast conditions, where reduced aperture throughput restricts the exit pupil; shooters facing these conditions are better served by an unrestricted standard 50mm objective lens or an open 56mm large-objective optic to maximise light transmission. Furthermore, it cannot mount to 40mm, 42mm, 56mm, or 60mm scopes, which require dedicated stop rings sized to their specific objective bell diameters.