Products Home / Optomechanical Components / Lens Tube Systems / Adapters and Accessories / Lens Tube Couplers and Locking RingsLens Tube Couplers and Locking Rings
- Connect Two Lens Tubes Together
- Threaded and Clamping Couplers Available
- Locking Rings Create Mechanical Stop Along Threads
- Options for SM05, SM1, SM1.5, SM2, SM3, and C-Mount Threading
SM2T1
Couples Two
Externally Threaded
SM2 Lens Tubes
CMT10
Couples Two
Internally Threaded
C-Mount Lens Tubes
SM1S10
Spacer for Two Internally Threaded SM1 Lens Tubes
SM1CPL
Shown Clamping Two
SM1 Lens Tubes
Application Idea
SM1CMM Shown Coupling Two KCB1 Kinematic Mirror Mounts
CMNT1
Slotted C-Mount
Locking Ring
Please Wait
Thorlabs' Lens Tube Couplers are available with internal threading, external threading, or clamping designs, making it possible to couple our SM05, SM1, SM2, or SM3 Lens Tubes, as well as our C-Mount Extension Tubes. Our threaded lens tube couplers are designed to couple two components with external threads or two components with internal threads. Locking rings for securing externally SM05-, SM1-, SM1.5-, SM2-, SM3-, and C-mount threaded parts are available as well.
Our Non-Rotating Couplers for SM1 Lens Tubes are ideal for mounting SM1-threaded components that are sensitive to rotation, such as wired components or lens tubes with polarization optics. Coupling adapters are threaded onto the lens tubes and then clamped together, allowing components to be joined without rotating the component. These light-tight couplers are also ideal for bridging existing lens tube systems.
The Flexure Sleeve Couplers allow lens tubes to be locked independently. The flexure clamping mechanism allows lens tubes to be positioned with either external or internal threads facing outward. These couplers feature a light-tight design. The SM1CPL Flexure Sleeve Couplers hold SM1 lens tubes and C-Mount extension tubes while the SM2CPL Flexure Sleeve Couplers hold SM2 lens tubes.
Click to Enlarge
The SM1T20 Lens Tube Coupler can be used to join sliding 30 mm cage system segments. In the photo above, the locking rings on the SM1T20 Coupler are tightened to retain the rotational alignment of the two cage segments. The cage rod flexure screws on the CP02F Cage Plate must be loosened to allow the cage segment on the right to slide.
Thorlabs' Threading Specifications
Thorlabs' lens tubes utilize a series of non-standard threadings. Threading specifications are given below for our SM threadings utilized in our lens tube and cage system components so that you can machine mating components to suit your application. We also offer products with C-Mount and RMS threadings, and the specifications for these threadings are also given below. Please note that other manufacturers may have different tolerances for these threads. For other thread specifications that are not listed here, please contact Tech Support.
| SM05 Threading: Ø1/2" Lens Tubes, 16 mm Cage Systems | |||
|---|---|---|---|
| External Thread, 0.535"-40.0, UNS-2A | Internal Thread, 0.535"-40.0, UNS-2B | ||
| Max Major Diameter | 0.5340" | Min Major Diameter | 0.5350" |
| Min Major Diameter | 0.5289" | Min Pitch Diameter | 0.5188" |
| Max Pitch Diameter | 0.5178" | Max Pitch Diameter | 0.5230" |
| Min Pitch Diameter | 0.5146" | Min Minor Diameter (and 83.3% of thread) | 0.508" |
| Max Minor Diameter | 0.5069" | Max Minor Diameter (and 64.9% of thread) | 0.514" |
| RMS Threading: Objective, Scan, and Tube Lenses | |||
|---|---|---|---|
| External Thread, 0.800"-36.0, UNS-2A | Internal Thread, 0.800"-36.0, UNS-2B | ||
| Max Major Diameter | 0.7989" | Min Major Diameter | 0.8000" |
| Min Major Diameter | 0.7934" | Min Pitch Diameter | 0.7820" |
| Max Pitch Diameter | 0.7809" | Max Pitch Diameter | 0.7866" |
| Min Pitch Diameter | 0.7774" | Min Minor Diameter (and 83.3% of thread) | 0.770" |
| Max Minor Diameter | 0.7688" | Max Minor Diameter (and 64.9% of thread) | 0.777" |
| C-Mount Threading: Machine Vision Lenses, CCD/CMOS Cameras | |||
|---|---|---|---|
| External Thread, 1.000"-32.0, UN-2A | Internal Thread, 1.000"-32.0, UN-2B | ||
| Max Major Diameter | 0.9989" | Min Major Diameter | 1.0000" |
| Min Major Diameter | 0.9929" | Min Pitch Diameter | 0.9797" |
| Max Pitch Diameter | 0.9786" | Max Pitch Diameter | 0.9846" |
| Min Pitch Diameter | 0.9748" | Min Minor Diameter (and 83.3% of thread) | 0.966" |
| Max Minor Diameter | 0.9651" | Max Minor Diameter (and 64.9% of thread) | 0.974" |
| SM1 Threading: Ø1" Lens Tubes, 30 mm Cage Systems | |||
|---|---|---|---|
| External Thread, 1.035"-40.0, UNS-2A | Internal Thread, 1.035"-40.0, UNS-2B | ||
| Max Major Diameter | 1.0339" | Min Major Diameter | 1.0350" |
| Min Major Diameter | 1.0288" | Min Pitch Diameter | 1.0188" |
| Max Pitch Diameter | 1.0177" | Max Pitch Diameter | 1.0234" |
| Min Pitch Diameter | 1.0142" | Min Minor Diameter (and 83.3% of thread) | 1.008" |
| Max Minor Diameter | 1.0068" | Max Minor Diameter (and 64.9% of thread) | 1.014" |
| SM30 Threading: Ø30 mm Lens Tubes | |||
|---|---|---|---|
| External Thread, M30.5x0.5 | Internal Thread, M30.5x0.5 | ||
| Max Major Diameter | 30.480 mm | Min Major Diameter | 30.500 mm |
| Min Major Diameter | 30.371 mm | Min Pitch Diameter | 30.175 mm |
| Max Pitch Diameter | 30.155 mm | Max Pitch Diameter | 30.302 mm |
| Min Pitch Diameter | 30.059 mm | Min Minor Diameter (and 83.3% of thread) | 29.959 mm |
| Max Minor Diameter | 29.938 mm | Max Minor Diameter (and 64.9% of thread) | 30.094 mm |
| SM1.5 Threading: Ø1.5" Lens Tubes | |||
|---|---|---|---|
| External Thread, 1.535"-40, UNS-2A | Internal Thread, 1.535"-40, UNS-2B | ||
| Max Major Diameter | 1.5339" | Min Major Diameter | 1.535" |
| Min Major Diameter | 1.5288" | Min Pitch Diameter | 1.5188" |
| Max Pitch Diameter | 1.5177" | Max Pitch Diameter | 1.5236" |
| Min Pitch Diameter | 1.5140" | Min Minor Diameter (and 83.3% of thread) | 1.508" |
| Max Minor Diameter | 1.5068" | Max Minor Diameter (and 64.9% of thread) | 1.514" |
| SM2 Threading: Ø2" Lens Tubes, 60 mm Cage Systems | |||
|---|---|---|---|
| External Thread, 2.035"-40.0, UNS-2A | Internal Thread, 2.035"-40.0, UNS-2B | ||
| Max Major Diameter | 2.0338" | Min Major Diameter | 2.0350" |
| Min Major Diameter | 2.0287" | Min Pitch Diameter | 2.0188" |
| Max Pitch Diameter | 2.0176" | Max Pitch Diameter | 2.0239" |
| Min Pitch Diameter | 2.0137" | Min Minor Diameter (and 83.3% of thread) | 2.008" |
| Max Minor Diameter | 2.0067" | Max Minor Diameter (and 64.9% of thread) | 2.014" |
| SM3 Threading: Ø3" Lens Tubes | |||
|---|---|---|---|
| External Thread, 3.035"-40.0, UNS-2A | Internal Thread, 3.035"-40.0, UNS-2B | ||
| Max Major Diameter | 3.0337" | Min Major Diameter | 3.0350" |
| Min Major Diameter | 3.0286" | Min Pitch Diameter | 3.0188" |
| Max Pitch Diameter | 3.0175" | Max Pitch Diameter | 3.0242" |
| Min Pitch Diameter | 3.0133" | Min Minor Diameter (and 83.3% of thread) | 3.008" |
| Max Minor Diameter | 3.0066" | Max Minor Diameter (and 64.9% of thread) | 3.014" |
| Posted Comments: | |
伟林 何
(posted 2019-12-11 08:51:41.717) "CMNT - C-Mount(1.00英寸-32)锁定环，1.25英寸外径"这个是2.8mm厚的，有没有更薄的，比如2mm及以下的？ llamb
(posted 2019-12-12 03:16:55.0) Thank you for your feedback. We can indeed offer custom, thinner versions of the CMNT locking ring. We have reached out to you directly to discuss potential quoting.
感谢您的反馈意见。 我们确实可以提供定制的，更薄版本的CMNT锁紧环。 我们已直接与您联系，讨论潜在的报价。 user
(posted 2014-10-13 16:41:59.227) On SM05 and SM1 couplers, can I confirm, as suggested by the Autocad PDF files, that two retaining rings are supplied and so aren't required as an additional order i.e. SM05T2 is sufficient for mounting two tubes and locking them in place? cdaly
(posted 2014-10-13 02:14:55.0) Response from Chris at Thorlabs: The internally threaded SM05T1 and SM1T1 couplers do not come with retaining rings. The externally threaded SM05T2 and SM1T2 couplers do both come with the two locking nuts shown. SM05T2 can be used to mount together two internally threaded ends of lens tubes, locking them in place with the provided nuts. steve
(posted 2013-06-04 00:01:55.8) How about an electrical isolating version (external and/or internal threads). For example, many laser diodes have their case electrically live and thus when mounted to your tubes, the whole tube assembly and whatever is connects to becomes connected. Especially an issue if you also mount a bare photodiode into a tube wince photodiodes also often have their case electrically active. I see you make Delrin adaptors for thermal isolation. tcohen
(posted 2013-06-06 12:45:00.0) Response from Tim at Thorlabs: Thank you for your suggestion. The anodization process used on the majority of our optomech makes them fairly electrically isolated. tcohen
(posted 2012-07-19 10:56:00.0) Response from Tim at Thorlabs: Thank you very much for your feedback! This can be done with lens tubes and the adapters on this page, but I agree that this would be a much more convenient solution. Our design team will look at this. ~1/3 of our products are customer inspired, including the original versions of these. Thank you for sharing your feedback so that we can continue to increase our selection with products directly relevant to your applications. nkad
(posted 2012-07-17 15:29:53.0) A much longer range of externally threaded SM1 coupling tubes would be really helpful, this would allow for a huge range of adjustment between enclosed optics. I would suggest 4" and 6". acable
(posted 2007-12-12 10:14:08.0) It would be really helpful to have photos for each of the individual parts shown on this page. |
ZoomThe SM05T1 is an internally threaded coupler for joining two externally threaded SM05 (0.535"-40) components. It is designed to directly mate two of our SM05-threaded standard lens tubes.
Thorlabs offers three externally threaded couplers for joining internally SM05-threaded components. These feature external threads along the entire length of the part, allowing for optimization of the position and angle of the attached components. Each coupler ships with two SM05NT locking rings, which can be tightened by hand to secure the attached components. Additional locking rings can be purchased separately to limit the external thread depth of any SM05-threaded components. The use of multiple locking rings allows lens tubes to be locked independently, such as when using crossed polarizers (see the video above for a demonstration).
For applications where it is difficult to reach the locking ring by hand, we offer the SM05NT1 Slotted Locking Ring and SPW502 Spanner Wrench. This locking ring contains slots for the 3/4" end of the spanner wrench. The SM05NT1V locking ring is a vacuum-compatible version of the SM05NT1 locking ring. Made from 6061-T6 aluminum, this unanodized locking ring is vacuum compatible down to 10-6 Torr.
The table below lists the specifications for all available couplers and locking rings.
| Item # | SM05T1 | SM05T2 | SM05T10 | SM05T20 | SM05NT | SM05NT1 | SM05NT1V |
|---|---|---|---|---|---|---|---|
| Description | SM05 Lens Tube Coupler | SM05 Locking Ring | Slotted SM05 Locking Ring | Vacuum-Compatible Slotted SM05 Locking Ring |
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| Threads | Internal SM05 | External SM05 | Internal SM05 | ||||
| Lengtha | 0.28" (7.1 mm) | 0.5" (12.7 mm) | 1.0" (25.4 mm) | 2.0" (50.8 mm) | 0.11" (2.8 mm) | ||
| Lens Tube Separation Rangeb |
N/A | 0.22" - 0.34" (5.6 mm - 8.6 mm) |
0.22" - 0.84" (5.6 mm - 21.3 mm) |
0.22" - 1.84" (5.6 mm - 46.7 mm) |
N/A | ||
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ZoomThe CMT1 is an internally C-Mount-threaded coupler for joining two externally threaded C-Mount (1.00"-32) components. Its length of 0.35" is designed for direct mating of two C-Mount Extension Tubes.
The CMT2 and CMT10 externally threaded couplers are designed for joining internally C-Mount-threaded components. These feature external threads along the entire length of the part, allowing the relative position and rotation of a camera and lens to be adjusted. Each coupler ships with two CMNT Locking Rings, which can be tightened by hand to secure the attached components. Additional locking rings can be purchased separately to limit the external thread depth of any C-Mount-threaded components. The use of multiple locking rings allows lens tubes to be locked independently, such as when using crossed polarizers (see the video above).
For applications where it is difficult to reach the locking ring by hand, we offer the CMNT1 Slotted Locking Ring and SPW502 Spanner Wrench. This locking ring contains slots for the 1¼" end of the spanner wrench.
The table below gives the specifications for all available couplers and locking rings.
| Item # | CMT1 | CMT2 | CMT10 | CMNT | CMNT1 |
|---|---|---|---|---|---|
| Description | C-Mount Extension Tube Coupler | C-Mount Locking Ring | C-Mount Slotted Locking Ring | ||
| Threads | Internal C-Mount | External C-Mount | Internal C-Mount | ||
| Lengtha | 0.35" (8.9 mm) | 0.5" (12.7 mm) | 1.0" (25.4 mm) | 0.11" (2.8 mm) | |
| Lens Tube Separation Rangeb |
N/A | 0.22" - 0.34" (5.6 mm - 8.6 mm) |
0.22" - 0.84" (5.6 mm - 21.3 mm) |
N/A | N/A |
| Drawing |  |
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ZoomThe SM1T1 is an internally SM1-threaded coupler for joining two externally threaded SM1 (1.035"-40) components. Its length of 0.28" is designed for direct mating of two standard lens tubes (SM1Lxx series).
Thorlabs offers five externally threaded couplers for joining internally SM1-threaded components. These feature external threads along the entire length of the part, allowing for optimization of the position and angle of the attached components. Each one ships with two SM1NT locking rings, which can be tightened by hand to secure the attached components. Additional locking rings can be purchased separately to limit the external thread depth of any SM1-threaded components. The use of multiple locking rings allows lens tubes to be locked independently, such as when using crossed polarizers (see the video above for a demonstration).
For applications where it is difficult to reach the locking ring by hand, we offer the SM1NT1 Slotted Locking Ring and SPW502 Spanner Wrench. This locking ring contains slots for the 1¼" end of the spanner wrench. The SM1NT1V locking ring is a vacuum-compatible version of the SM1NT1 locking ring. Made from 6061-T6 aluminum, this unanodized locking ring is vacuum compatible down to 10-6 Torr.
For a one-component solution for spacing two externally threaded SM1 components at a fixed distance, please see our line of lens tubes without external threads, available in lengths ranging from 0.5" to 3.5". For a one-component solution for spacing internally threaded SM1 components at a fixed distance, see our selection of SM1 Lens Tube Spacers below.
The table below gives the specifications for all available couplers and locking rings.
| Item # | SM1T1 | SM1T2 | SM1T10 | SM1T20 | SM1T30 | SM1T40 | SM1NT | SM1NT1 | SM1NT1V |
|---|---|---|---|---|---|---|---|---|---|
| Description | SM1 Lens Tube Coupler | SM1 Locking Ring | Slotted SM1 Locking Ring | Vacuum-Compatible Slotted SM1 Locking Ring |
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| Threads | Internal SM1 | External SM1 | Internal SM1 | ||||||
| Lengtha | 0.28" (7.1 mm) | 0.5" (12.7 mm) | 1.0" (25.4 mm) | 2.0" (50.8 mm) | 3.0" (76.2 mm) | 4.0" (101.6 mm) | 0.11" (2.8 mm) | ||
| Lens Tube Separation Rangeb |
N/A | 0.22" - 0.34" (5.6 mm - 8.6 mm) |
0.22" - 0.84" (5.6 mm - 21.3 mm) |
0.22" - 1.84" (5.6 mm - 46.7 mm) |
0.22" - 2.84" (5.6 mm - 72.1 mm) |
0.22" - 3.84" (5.6 mm - 97.5 mm) |
N/A | ||
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- Use as Spacers Between Lens Tubes
- External SM1 Threading on Each End
- Six Lengths Ranging from 1.0" (25.4 mm) to 3.5" (88.9 mm)
These externally threaded Lens Tube Spacers are designed to connect two components with internal SM1 threads at a fixed distance. They are internally unthreaded and have a clear aperture of Ø0.95" (Ø24.0 mm).
The figure to the right shows two SM1L30C slotted lens tubes holding two plano-convex lenses. Separating these is the SM1S30 lens tube spacer, attached to a post with an SM1RC lens tube slip ring. Lens tube spacers allow significant space to be added between two fixed lenses using only one component.
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- Allows Coupling of Two Externally SM1-Threaded Components
- Use with Lens Tube Couplers to Stack Multiple Lens Tubes
- Seven Lengths Ranging from 1/2" (12.7 mm) to 3.5" (88.9 mm)
These internally threaded Lens Tubes are designed to connect two components with external SM1 threads. Alternatively, optics can be housed inside with access to both ends. To join these lens tubes end-to-end, use an SM1 Lens Tube Coupler, sold above. Two SM1RR Retaining Rings are included with each lens tube.
| Alternatives | Ø1/2" and Ø2" Lens Tubes Without External Threads | ||
|---|---|---|---|
Zoom| Bundle Contents | ||
|---|---|---|
| Item # | Adapters | Coupler |
| SM1CFF | Two Internal SM1 Adapters (SM1CF) | Clamp and Centering Ring (SM1CH) |
| SM1CMF | Internal SM1 Adapter (SM1CF) | |
| External SM1 Adapter (SM1CM) | ||
| SM1CMM | Two External SM1 Adapters (SM1CM) | |
- Non-Rotating, Light-Tight Coupler Connects SM1 Lens Tubes
- Clamp Housing Binds Separate SM1-Threaded Assemblies Together
- Clamp and Thread Mating Adapters Available in Bundles or as Separate Components
- Compatible with KF25 Vacuum Hardware*
- #8 (M4) Counterbore for use with Ø1/2" Posts
Thorlabs' Non-Rotating SM1 Lens Tube Couplers enable SM1-threaded (1.035"-40) lens tubes or components to be joined without rotating the component to engage the SM1 thread. This allows SM1 lens tube systems to be mated without changing the orientation, which is critical in polarization applications. These couplers also allow SM1-threaded components, such as our power meter sensors or other SM1-threaded detectors, to be attached to a system without coiling the sensor cable.
To join two SM1-threaded components together, an adapter with internal or external threads is attached to each part. An aluminum centering ring with a Viton® O-Ring is inserted between the adapters and the parts are pressed together. The clamp housing is then engaged using a 5/64" (2.0 mm) hex key, which compresses the adapters and O-ring together, creating a light-tight and airtight seal. The clamp housing offers a #8 (M4) counterbore for mounting to our Ø1/2" Posts.
*Due to the outgassing of anodized aluminum, this coupler is not suitable for vacuum applications. Only the coupling adapters are compatible with KF25 centering rings and clamping hardware. For purging applications, positive pressure can be maintained up to 50 psi (3.4 bar).
Click for Details
SM1CMF Coupler Diagram
SM1CMF Installation
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- Flexure Design Holds SM1 Lens Tubes, C-Mount Extension Tubes, or Other Ø1.2" Outer Diameter Cylindrical Objects
- Available in Three Lengths: 0.5", 1.0", and 3.0"
- RTV103 Black Silicone Gasket Provides Light-Tight Coupling
- Lens Tubes can be Positioned Along the Entire Length, Facing Either Direction
These Lens Tube Couplers are flexure-clamping sleeves that can hold any Ø1" lens tube, C-Mount extension tube, or other Ø1.2" outer diameter cylindrical object. A lens tube can be slid into each end of the coupler and secured by tightening the two 5/64" (2 mm) hex screws on the side of the sleeve.
Each coupler features a black silicone gasket along the clamping section to provide light-tight coupling of lens tubes (see photos to the right). Lens tubes can be mounted with either internal or external threads facing out and at any position along the length of the coupler as long as there are at least 6 mm of the tube inside the clamp.
Zoom| Item # | SM1.5NT |
|---|---|
| Description | SM1.5 Locking Ring |
| Threads | Internal SM1.5 |
| Length | 0.11" (2.8 mm) |
| Drawing |  |
The SM1.5T Locking Ring has internal SM1.5 (1.535"-40) threads and a knurled outer edge. It can be used to limit the external thread depth of any SM1.5-threaded components such, as the KAD1F kinematic adapter. The use of two locking rings allows lens tubes to be locked in independent rotational orientations on both ends of an SM1.5-threaded component. Alternatively, a pair of locking rings screwed against each other may be used to create a hard stop.
See the table to the right for specifications.
ZoomThe SM2T1 is an internally threaded coupler for joining two externally threaded SM2 (2.035"-40) components. It is designed to directly mate two of our SM2-threaded standard lens tubes.
Thorlabs offers three externally threaded couplers for joining internally SM2-threaded components. These feature external threads along the entire length of the part, allowing for optimization of the position and angle of the attached components. Each coupler ships with two SM2NT locking rings, which can be tightened by hand to secure the attached components. Additional locking rings can be purchased separately to limit the external thread depth of any SM2-threaded components. The use of multiple locking rings allows lens tubes to be locked independently, such as when using crossed polarizers (see the video above for a demonstration).
For applications where it is difficult to reach the locking ring by hand, we offer the SM2NT1 Slotted Locking Ring and SPW503 Spanner Wrench. This locking ring contains slots for the 2¼" end of the spanner wrench.
The table below gives the specifications for all available couplers and locking rings.
| Item # | SM2T1 | SM2T2 | SM2T10 | SM2T20 | SM2NT | SM2NT1 |
|---|---|---|---|---|---|---|
| Description | SM2 Lens Tube Coupler | SM2 Locking Ring | SM2 Slotted Locking Ring | |||
| Threads | Internal SM2 | External SM2 | Internal SM2 | |||
| Lengtha | 0.26" (6.6 mm) | 0.5" (12.7 mm) | 1.0" (25.4 mm) | 2.0" (50.8 mm) | 0.11" (2.8 mm) | |
| Max Adjustment Rangeb | N/A | 0.22" - 0.34" (5.6 mm - 8.6 mm) |
0.22" - 0.84" (5.6 mm - 21.3 mm) |
0.22" - 1.84" (5.6 mm - 46.7 mm) |
N/A | |
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Zoom
Click to Enlarge
An SM2CPL10 holding two Ø2" lens tubes. A rubber gasket makes the coupler light tight.
Click to Enlarge
Lens Tubes Are Secured by Tightening Two 5/64" Hex Screws
- Flexure Design Holds SM2 Lens Tubes or Other Ø2.2" Outer Diameter Cylindrical Objects
- Gasket Provides Light-Tight Coupling
- Lengths of 0.5" or 1.0"
- Lens Tubes can be Positioned Along the Entire Length, Facing Either Direction
These Lens Tube Couplers are flexure-clamping sleeves that can hold any Ø2" lens tube or other Ø2.2" outer diameter cylindrical object. A lens tube can be slid into each end of the coupler and secured by tightening the two 5/64" (2 mm) hex screws on the side of the sleeve.
Each coupler features a black silicone gasket along the clamping section to provide light-tight coupling of lens tubes (see photos to the right). The coupled lens tubes may be clamped with either the internal or external threads facing out and any position along the length of the coupler as long as there are at least 6 mm of the tube inside the clamp.
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| Item # | SM3T1 | SM3T2 | SM3NT |
|---|---|---|---|
| Description | SM3 Lens Tube Coupler | SM3 Lock Nut | |
| Threads | Internal SM3 | External SM3 | Internal SM3 |
| Lengtha | 0.28" (7.1 mm) |
0.5" (12.7 mm) |
0.11" (2.8 mm) |
| Max Adjustment Rangeb | N/A | 0.22" - 0.34" (5.6 - 8.6 mm) |
N/A |
| Drawing |  |
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The SM3T1 is an internally threaded coupler for joining two externally threaded SM3 (3.035"-40) components. It is designed to directly mate two of our SM3-threaded standard lens tubes.
The SM3T2 Coupler features external SM3 threading (3.035"-40), which enables the coupling of two components with internal SM3 threads. It ships with two SM3NT locking rings, which can be used to lock the position of an attached SM3 component.
Additional locking rings (Item # SM3NT) can be purchased separately to limit the external thread depth of any SM3-threaded components. The use of multiple locking rings is particularly desirable in situations where you have two components with preferential relative directions, such as when using crossed polarizers (see the video above for a demonstration).
The table to the right gives the specifications for all available items.
Lens Tube Couplers and Locking Rings