Astrodymium ZWO EAF Adapter/Mount for Rokinon - Samyang 135mm lens

AstrodymiumSKU: RS-EAF.S

Location: Side Mounted
Sale price$19.99


Please note: This adapter is meant only for use alongside the Astrodymium Ring System - it will not work without it.

Get autofocus for your Rokinon/Samyang 135mm lens!

The ZWO EAF adapter for the Astrodymium Ring System will allow you to electronically control focus on the 135mm lens. This opens up the possibility of unattended/automated imaging sessions, where you don't have to worry about focus shift due to temperature or filter changes.

The Astrodymium Ring System is the only autofocusing solution on the market that has the choice of where to position the ZWO EAF on the 135mm lens. 

Please note that there are pros and cons to each location. Most users should choose the side-mounted version, but refer to the following table for more details to consider:

Location Pros  Cons
  • Less expensive
  • Easier to install and remove (5min)
  • Center of gravity is closer to the rotation point, resulting in less weight needed for proper balance (good for star tracker users)
  • Weight is off-center to one side
  • Setup is not lifted any higher, risers may be needed for better clearance (RS-RISER).
  • Only 1 side of the lens is free to add additional accessories to.
  • Entire ring system is lifted over 2" (50mm) from the dovetail bar, allowing ample clearance for filter wheels or accessories
  • Weight of the ZWO EAF is in line with the rest of the lens, due to being below it and in the center
  • Both sides of the lens are free for additional add-ons
  • More expensive
  • Installation and removals take longer (10min)
  • Higher center of gravity, resulting in more counterweight needed for proper balance (not an issue on regular mounts)


All printed parts for the EAF adapter are made out of PETG plastic that can handle temperatures of up to 75C (149F), and down to -25C (-13F). 

What's included (see each picture for specifics):

  • Fasteners
  • 1x Timing belt
  • 1x Metal pulley
  • Printed parts (Focus ring, eaf bracket, etc)

Lens, dovetail bar, Ring System, and ZWO EAF are not included and only shown for illustrative purposes.

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