Rokinon 135mm and Sigma ART Ring Systems

Posted on Wednesday, August 6, 2025 by RICHARD HARRIS, Executive Editor

The Nightfall Ring Platform for the Sigma ART 85mm F1.4 lens is built for widefield astrophotography setups that require stability and the ability to mount several components in one place. It is compatible with Canon and Nikon versions of the lens and can hold accessories such as a ZWO Electronic Auto Focuser, a guidescope, a filter wheel, an ASIAIR or miniPC, and a power distribution unit. A piggyback camera can be attached when using the optional ballhead adapter plate.

Rokinon 135mm and Sigma ART Ring Systems

The platform is made in the USA and uses 3D printed parts from PETG and PLA+ thermoplastics, which can handle outdoor temperatures from -15°F to 175°F. All mounting hardware is stainless steel, and the thumbscrews are red anodized aluminum for visibility.

The standard mounting kit includes two heavy-duty mounting rings, a Vixen accessory saddle rail, two red anodized thumbscrews for the accessory saddle, two red anodized thumbscrews for the mounting rings, various stainless steel mounting screws, and two M6 socket screws for attaching the mounting rings to a dovetail bar.

The optional ZWO EAF mounting kit comes with everything from the standard kit, plus a focus gear assembly, timing belt, timing pulley, and a ZWO EAF mounting bracket with a stainless steel screw. This makes it easy to integrate automated focusing into the setup, which can improve sharpness and reduce manual adjustments during long imaging sessions.

The Nightfall Ring Platform for the Rokinon 135mm F2.0 lens, also compatible with the Samyang 135mm F2.0, is designed for users who want a secure and stable mounting solution that can hold multiple accessories for a fully automated widefield imaging setup. The design of this platform addresses common issues found in other lens mounting systems, such as undersized or weak rings, poor mounting space for accessories, and inefficient dew heater placement.

One improvement is the forward placement of the front ring mount. This allows a dew heater to be installed directly on the metal barrel of the lens, which improves heat transfer to the optical elements compared to heaters mounted only on the plastic lens hood. The rings are larger and more durable than many other systems, providing more room to mount devices like a miniPC, a power distribution module, or a USB hub. The spacing between the front and rear rings is also increased to accommodate larger accessory plates, giving more room for additional gear.

This model is made for use with dedicated astro cameras, such as the ZWO ASI series, due to the rear-mounted ZWO EAF design. This arrangement does not leave enough clearance for DSLR bodies. The platform is manufactured in the USA, using PETG and PLA+ materials that withstand harsh weather conditions, and all screws and fittings are stainless steel.

The standard kit includes two heavy-duty mounting rings, a Vixen accessory saddle rail, two red anodized thumbscrews for the accessory saddle, two red anodized thumbscrews for the mounting rings, miscellaneous stainless steel screws, and two M6 socket screws for attaching the mounting rings to a dovetail bar.

The ZWO EAF mounting kit includes all the parts from the standard kit, plus the focus gear assembly, timing belt, timing pulley, and the EAF mounting bracket with its stainless steel mounting screw. This makes it possible to add fully automated focusing to the Rokinon 135mm imaging setup, allowing for reliable and repeatable focus control during long imaging runs.

The Nightfall Ring Platform for the Sigma ART 50mm F1.4 lens is made for astrophotographers looking to create a widefield imaging system with one of the widest fields of view available for this type of setup. The platform can support accessories such as a ZWO Electronic Auto Focuser, guidescope, filter wheel, ASIAIR or miniPC, and a power distribution unit. The optional ballhead adapter plate allows mounting a piggyback camera as well.

Like the other models, this platform is made in the USA using PETG and PLA+ thermoplastics for durability in outdoor conditions. Stainless steel hardware and red anodized aluminum thumbscrews are used throughout for reliability and ease of use in the field.

The standard mounting kit includes two heavy-duty mounting rings, a Vixen accessory saddle rail, two red anodized thumbscrews for the accessory saddle, two red anodized thumbscrews for the mounting rings, various stainless steel mounting screws, and two M6 socket screws for attaching the mounting rings to a dovetail bar.

The ZWO EAF mounting kit adds the components needed for automated focusing: a focus gear assembly, timing belt, timing pulley, and a ZWO EAF mounting bracket with stainless steel mounting screw, in addition to all parts from the standard kit. This allows integration of autofocus into the setup, which can help keep focus consistent during imaging runs.

All three Nightfall Ring Platform models share the same overall design concept, with heavy-duty rings, a Vixen accessory saddle, and optional support for a ZWO EAF system. Each is designed for a specific lens and offers the ability to mount additional imaging and control equipment, creating a complete widefield astrophotography rig.

The Sigma ART 85mm version is suited for medium-wide field imaging, offering about twice the field of view of a 135mm lens. The Rokinon 135mm version is a longer focal length option with a track record for producing sharp and detailed widefield images. The Sigma ART 50mm version has the widest field of view, making it possible to frame entire constellations in a single image.

Each platform is constructed from durable, weather-resistant materials and includes stainless steel hardware for long-term reliability. Optional ZWO EAF mounting kits allow automated focusing for improved precision, especially during long exposure sequences and remote operation. These platforms are aimed at astrophotographers who want a sturdy and expandable solution for building a complete imaging system around their lens of choice.

Nightfall Ring Platform for Sigma ART 85mm F1.4 Lens specifications

  • Designed, engineered, and manufactured in the USA
  • Components 3D printed using advanced thermoplastics PETG and PLA+ (tough)
  • Water-resistant and withstands outdoor conditions from -15°F to +175°F
  • All hardware is 18-8 stainless steel
  • Thumbscrews are red anodized aluminum
  • Compatible with Sigma ART 85mm F1.4 lens for Canon or Nikon
  • Standard mounting kit includes:
  • Two heavy-duty mounting rings
  • Vixen accessory saddle rail
  • Two red anodized thumbscrews for accessory saddle
  • Two red anodized thumbscrews for mounting rings
  • Misc. 18-8 stainless steel mounting screws
  • Two M6 socket screws for mounting rings to dovetail bar
  • ZWO EAF mounting kit includes:
  • All items in the standard mounting kit
  • Focus gear assembly
  • Timing belt
  • Timing pulley
  • ZWO EAF mounting bracket with stainless steel mounting screw
     

Sigma ART 135mm F1.4 Ring Platform specifications

  • Designed, engineered, and manufactured in the USA
  • Components 3D printed using advanced thermoplastics PETG and PLA+ (tough)
  • Water-resistant and withstands outdoor conditions from -15°F to +175°F
  • All hardware is 18-8 stainless steel
  • Thumbscrews are red anodized aluminum
  • Front ring mount positioned forward to allow dew heater installation directly on the metal lens body for efficient heating
  • Heavy-duty, larger ring mounts to prevent breakage and provide more mounting space
  • Maximum spacing between front and rear rings for larger accessory plates and more components
  • Compatible only with dedicated astro cameras (e.g., ZWO ASI series) due to ZWO EAF clearance requirements
  • Compatible with Rokinon 135mm F2.0 and Samyang 135mm F2.0 lenses
  • Standard mounting kit includes:
  • Two heavy-duty mounting rings
  • Vixen accessory saddle rail
  • Two red anodized thumbscrews for accessory saddle
  • Two red anodized thumbscrews for mounting rings
  • Misc. 18-8 stainless steel mounting screws
  • Two M6 socket screws for mounting rings to a dovetail bar
  • ZWO EAF mounting kit includes:
  • All items in the standard mounting kit
  • Focus gear assembly
  • Timing belt
  • Timing pulley
  • ZWO EAF mounting bracket with stainless steel mounting screw
     

Sigma ART 50mm F1.4 Ring Platform specifications

  • Designed, manufactured, and assembled in the USA
  • Components 3D printed using advanced thermoplastics PETG and PLA+ (tough)
  • Water-resistant and withstands outdoor conditions from -15°F to +175°F
  • All hardware is 18-8 stainless steel
  • Thumbscrews are red anodized aluminum
  • Compatible with Sigma ART 50mm F1.4 lens for Canon or Nikon
  • Standard mounting kit includes:
  • Two heavy-duty mounting rings
  • Vixen accessory saddle rail
  • Two red anodized thumbscrews for accessory saddle
  • Two red anodized thumbscrews for mounting rings
  • Misc. 18-8 stainless steel mounting screws
  • Two M6 socket screws for mounting rings to a dovetail bar
  • ZWO EAF mounting kit includes:
  • All items in the standard mounting kit
  • Focus gear assembly
  • Timing belt
  • Timing pulley
  • ZWO EAF mounting bracket with stainless steel mounting screw
     

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