SM-Threaded Adapters for Square Filters

  • Mount Square Optics on SM-Threaded Components
  • Ideal for Plate Filters


SM1 (1.035"-40) Adapter for 1" Square Optics


SM2 (2.035"-40) Adapter for 2" Square Optics
(Filter Not Included)





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Item # SM1FH SM2FH
Accepted Optic Size 1" or 25 mm Square 2" or 50 mm Square
Max Optic Thickness 0.18" (4.6 mm)
Clear Aperture Ø0.95" (Ø24.0 mm) Ø1.90" (Ø48.3 mm)
Threading External SM1 (1.035"-40)
0.25" (6.3 mm) Deepa
External SM2 (2.035"-40)
0.25" (6.3 mm) Deepa
Included Locking Ring SM1NT1 SM2NT1
Outer Diameter 2.00" (50.8 mm) 3.00" (76.2 mm)
  • Without the included 0.11" (2.8 mm) thick locking ring installed.


  • Mount Square Optics onto Internally SM-Threaded Components
  • Spring-Loaded Clips Secure Optic

These adapters accept square optics and have external SM threading for mounting to other internally SM-threaded components, such as lens tubes. Each adapter has two spring-loaded clips that can hold an optic up to 0.18" (4.6 mm) thick. The SM1FH adapter has SM1 (1.035"-40) threads and accepts 1" or 25 mm square optics, while the SM2FH adapter has SM2 (2.035"-40) threads and accepts 2" or 50 mm square optics. The spring-loaded clips can be tightened using a 0.05" (1.3 mm) hex key.

Each adapter includes a locking ring that allows the optic to be positioned in a specific orientation when the adapter is attached to an SM-threaded component. The locking rings can be tightened by using the SPW502 spanner wrench (for Item # SM1NT1) or SPW503 spanner wrench (for Item # SM2NT1). The adapters are also designed with outer diameters that allow them to be mounted in our smooth-bore mirror mounts.

We also offer Fast-Change Filter Holders for use in lens tube systems and a wide variety of Post-Mountable Rectangular Plate Optic Mounts.

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SM Thread Adapters for Square Filters

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
SM1FH Support Documentation
SM1FHNEW!SM1-Threaded Adapter for 1" Square Filters
SM2FH Support Documentation
SM2FHNEW!SM2-Threaded Adapter for 2" Square Filters