Adjustable SM05 Lens Tubes

  • Rotating Adjustment of Ø1/2" Optics
  • 0.31" (7.9 mm) or 0.81" (20.6 mm) Adjustment Range
  • SM05 (0.535"-40) Threading
  • Max Optic Thickness: 0.43" (11.0 mm)

A lens housed in an SM05V05 that is threaded into an SM05L15 lens tube is used to focus light onto the detector.


Ø1/2" Adjustable Lens Tube,
0.31" Travel Range


Ø1/2" Adjustable Lens Tube
0.81" Travel Range


Ø1/2" Vacuum-Compatible Adjustable Lens Tube,
0.31" Travel Range

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SM05V05 Adjustable Lens Tube Mechanical Drawing
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Amin and Amax are the minimum and maximum distances another lens tube can be positioned from the back of the lens cell when using the locking ring.


  • Long Externally-Threaded Section for Adjustable Positioning of Mounted Optics
  • Available Adjustment Ranges: 0.31" (7.9 mm) or 0.81" (20.6 mm)
  • Holds Ø1/2" (Ø12.7 mm) Optics
  • Maximum Optic Thickness of 0.43" (11.0 mm)
  • One Retaining Ring and Locking Ring Included
  • Vacuum-Compatible Version with 0.31" (7.9 mm) Adjustment Range

These SM05-threaded (0.535"-40) adjustable lens tubes allow Ø1/2" optics to be precisely positioned along the optical axis of a lens tube system. To operate, mount the optic in the adjustable-length lens tube using the included retaining ring. Then thread the adjustable lens tube into a compatible SM05-threaded lens tube or lens mount until the optic is at the desired position. At this point, the included locking ring can be used to fix the position of the lens tube. These rotating adjustable lens tubes are an ideal solution for fine tuning of the first and last lenses in a lens tube system. Although a lens tube can be attached to the front of the adjustable lens tube, it should only be done after the position of the optic has been fixed since this lens tube will need to be free to rotate and translate if the position of the optic is changed.

The SM05V05 and SM05V10 adjustable lens tubes include one SM05RR retaining ring and one SM05NT locking ring. 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 SM05V05V adjustable lens tube is a vacuum-compatible version of the SM05V05 lens tube with the addition of vented channels along its threading and at the ends the tube. These channels allow air trapped between mounted optics an easy means of escape during pumpdown. The lens tube comes with an SM05RRV retaining ring and SM05NT1V locking ring. All components are made from 6061-T6 aluminum, allowing this adjustable lens tube to be vacuum compatible down to 10-6 Torr.

Item # External Thread Length (L) Adjustment Range (Amin to Amax)a
SM05V05(V) 0.5" (12.7 mm) 0.11" - 0.42" (2.8 mm - 10.7 mm)
SM05V10 1.0" (25.4 mm) 0.11" - 0.92" (2.8 mm - 23.4 mm)
  • Amin includes the thickness of the included locking ring, while Amax accounts for the minimum 0.08" (2 mm) thread depth needed to engage the attached lens tube or component.
Alternatives Ø1", Ø1.5"Ø2", and Ø3" Adjustable Lens Tubes

Threading Specifications

The following is a general overview of screw threading. For more details regarding specifications and dimensions, please consult the Machinery's Handbook, available for purchase at many bookstores.

Features of a Thread
A thread consists of three repeating features: a crest, flank, and root (see drawing to the right). Except in special cases, threads have symmetrical sides inclined at equal angles when a vertical line is drawn through the center of a crest or root. The distance between corresponding points on adjacent threads is known as the pitch of the thread. The flank angle is defined as the angle the flank makes with a perpendicular ray drawn from the screw axis. Unless otherwise stated, threads have a flank angle of 30°, resulting in a total angle between flanks of 60°. Each feature is shown in the diagram to the right.

The major diameter is taken from the crests of a thread while the minor diameter is taken from the roots. For most screws, crests and roots do not terminate at a sharp point, so crest and root truncation values are included in the definitions of major and minor diameter. The pitch diameter is approximately halfway between the major and minor diameters.

Thread Form
A thread form is a set of rules that define the features' scale relative to one another. Common thread forms include the Unified Screw Thread Form, used in the United States of America and measured in imperial units, and the ISO Metric Screw Thread Form, used in many parts of the world and measured with the International System of Units. There are many thread forms in the Unified screw thread standard designated by either UN, which defines a flat root contour, or UNR, which defines a round root contour. These can be further described by appending more letters. For example, an extremely fine thread with a flat root contour is designated UNEF. Those forms which are not standardized by the Unified screw thread system are designated UNS.

Thread Series
Most screws are identified by their thread series. Thread series are denoted by the major diameter and density of threads. Unified threads specify density in threads per inch, while Metric threads specify the thread pitch. For example, in the Unified nomenclature, a 1/4"-20 cap screw has a 1/4" diameter barrel and the pitch is 20 threads per inch (TPI). In metric nomenclature, an M4 x 0.7 cap screw has a 4 mm barrel and the pitch is 1 thread per 0.7 mm. The term M4 x 0.7 is often shortened to just M4.

Unified Thread Class Tolerancing
Location Loose Optimal Strict
Internal 1B 2B 3B
External 1A 2A 3A
Metric Thread Tolerance Positions
Location Loose Optimal Strict
Internal - G H
External e or f g h
Metric Thread Tolerance Grades
Dimension Location Tolerance Gradesa
Minor Diameter Internal 4, 5, 6, 7, 8
Major Diameter External 4, 6, 8
Pitch Diameter Internal 4, 5, 6, 7, 8
External 3, 4, 5, 6, 7, 8, 9
  • The tolerance becomes looser as the grade increases. The underlined grades are used with normal lengths of thread engagement.

Thread Class
The tolerances and allowances on a thread series are given by a thread class. Unified thread classes are alphanumeric identifiers starting with a number from 1 through 3, where 1 is the loosest tolerance and 3 is the tightest, and either A for external threading or B for internal threading.

Metric threads have a slightly more complex tolerancing method that uses tolerancing grades, designated by a number 3 through 9; and tolerancing positions, which use letters e through h. Grades provide a measure of the tolerance itself: the smaller the number, the tighter the tolerance. Positions denote the distance of the tolerance from the pitch diameter. Uppercase positioning letters indicate internal threads while lowercase positioning letters indicate external threads.

Quoting from the Machinery's Handbook, 29th Edition, p. 1885: "To designate the tolerance class, the grade and position of the pitch diameter is shown first followed by that for the major diameter in the case of the external thread or that for the minor diameter in the case of the internal thread, thus 4g6g for an external thread and 5H6H for an internal thread. If the two grades and positions are identical, it is not necessary to repeat the symbols, thus 4g, alone, stands for 4g4g and 5H, alone, stands for 5H5H."

Thorlabs' SM Series Threads
Threading specifications for our SM threads, utilized in our lens tube and cage system components, are given below so that you can machine mating components to suit your application. Most SM series threads utilize a non-standard Unified thread form, indicated by the letters UNS, with a 30° flank angle and a thread class of 2A and 2B. The exception is our SM30 series thread, which is a Metric thread form with a 30° flank angle and a tolerance of 6H/6g. We also offer products with C-Mount and RMS threads, and the specifications for these threads are given below for reference. Please note that other manufacturers may have different tolerances for C-Mount and RMS 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, M30.5 x 0.5 – 6H/6g Internal Thread, M30.5 x 0.5 – 6H/6g
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"
SM4 Threading: Ø4" Lens Tubes
External Thread, 4.035"-40 UNS-2A Internal Thread, 4.035"-40.0 UNS-2B
Max Major Diameter 4.0337" Min Major Diameter 4.0350"
Min Major Diameter 4.0286" Min Pitch Diameter 4.0188"
Max Pitch Diameter 4.0175" Max Pitch Diameter 4.0245"
Min Pitch Diameter 4.0131" Min Minor Diameter (and 83.3% of Thread) 4.008"
Max Minor Diameter 4.0066" Max Minor Diameter (and 64.9% of Thread) 4.014"

Posted Comments:
user  (posted 2019-12-05 12:56:34.167)
Does the adjustable lens tube allow rotation of the optic independent of translation? The 2D hatched section view looks like it might, but the 3D CAD model does not, showing it as a single body.
llamb  (posted 2019-12-06 01:35:42.0)
Thank you for your feedback. Besides the included locking nut and retaining ring, the SM05V05 is a single body. The tube itself will not rotate the optic without translation.
stepan.vyhlidka  (posted 2018-06-29 09:41:49.213)
Hello, the locking ring SM05NT does not fit in between 16 mm cage construction rods (it cannot be rotated then - locked/unlocked). We bough one to tune the position of the lens to collimate the fiber within cage assembly. Could you decrease its diameter?
YLohia  (posted 2018-07-03 10:14:36.0)
Hello, thank you for your feedback. I have posted this idea in our internal engineering forum. Reducing the diameter would indeed make this compatible with the 16mm cage system.
cpv  (posted 2017-11-27 16:23:27.433)
How can I couple this SM05V10 to a c-female thread? In other words, I would like a c-mount coupler to my 1/2'' lens. What can you offer? Best Regards, César
nbayconich  (posted 2017-12-04 11:31:50.0)
Thank you for contacting Thorlabs. We have a C-mount to SM05 adapter part number SM05A1 which can adapt the SM05V10 to a c-mount threaded camera using another SM05 lens tube. More information about our thread adapters can be found in the link below.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
SM05V05 Support Documentation
SM05V05 Ø1/2" Adjustable Lens Tube, 0.31" Travel
SM05V05V Support Documentation
SM05V05VVacuum-Compatible Ø1/2" Adjustable Lens Tube, 0.31" Travel
SM05V10 Support Documentation
SM05V10Ø1/2" Adjustable Lens Tube, 0.81" Travel