Microscope Objective Threading Adapters


  • Integrate Objectives with Industry-Standard Threads into Nosepieces with RMS, M25 x 0.75, M32 x 0.75, or SM2 Threads 
  • Options Compatible with Thorlabs’ Bergamo® and Cerna® Microscope Systems

M32RMSS

External M32 x 0.75 Threads
and Internal RMS Threads

M32M34S

External M32 x 0.75 Threads
and Internal M34 x 1.0 Threads

CSN100

M32M25S

N40X-PF

M32M25S Adapter Connecting a Nikon Objective to a Cerna Nosepiece

M2M40S

External SM2 Threads and Internal M40 x 0.706 Threads

Related Items


Please Wait
Item # Internal Threads External Threads
RMSW26S W26 x 0.706a,b,c RMS (0.800"-36)
M25W26S W26 x 0.706a,b,c M25 x 0.75
M32RMSS RMS (0.800"-36)a,d,e M32 x 0.75
M32M25S M25 x 0.75a,d,e
M32SM1S SM1 (1.035"-40)
M32W26S W26 x 0.706a,b,c
M32M27S M27 x 0.75f
M32M271S M27 x 1.0f
M32M32S M32 x 0.75d,e,f
M32M34S M34 x 1.0a
M32M40S M40 x 0.706b
M2M32S M32 x 0.75d,e,f SM2 (2.035"-40)
M2M34S M34 x 1.0a
M2M40S M40 x 0.706b
  • These threads are used by select Olympus objectives.
  • These threads are used by select Thorlabs and Mitutoyo objectives. 
  • W26-threaded objectives are sometimes referred to as M26-threaded, but as long as the objective conforms to ISO 9345:2019 or JIS B 7141:2012, it will be compatible with our W26 adapters.
  • These threads are used by select Nikon objectives.
  • These threads are used by select Leica objectives.
  • These threads are used by select Zeiss objectives.

Features

  • Externally RMS (0.800"-36)- and M25 x 0.75-Threaded Adapters Compatible with Internally Threaded Turrets and Nosepieces
  • Externally M32 x 0.75-Threaded Adapters Compatible with Bergamo® and Cerna® Microscope Systems
  • Externally SM2-Threaded Adapters Compatible with the CSA2100 Cerna Mounting Arm
  • Internal Threading Compatible with Thorlabs, Mitutoyo, Olympus, Nikon, Zeiss, and Leica Objectives
  • Lip Prevents Over-Threading into Microscope Nosepieces
  • Solid Brass Construction

These Brass Microscope Adapters can mate an externally threaded microscope objective to an internally RMS (0.800"-36)-, M25 x 0.75-, M32 x 0.75- or SM2-threaded nosepiece. The design includes a flange to prevent over-threading the adapter or the objective into a microscope nosepiece, keeping the objective at the proper position and preventing damage to the optics inside the housing. In addition, the brass construction is harder than aluminum which reduces thread binding. The M32M32S adapter was created since many M32 x 0.75 threaded nosepieces have recessed threads. Due to the large diameter of some objectives, such as the TL10X-2P, a smaller diameter mount is needed to properly load in certain mating pieces. Each adapter has spanner wrench holes or slots for compatibility with our SPW801 Adjustable Spanner Wrench to help thread the adapters into a microscope nosepiece. 

To view our entire line of thread adapters, please see our Interactive Adapters Selection Guide. As detailed above, we do not recommend using aluminum adapters with microscope objectives.

Item # Typical Application External Threads Internal Threads
RMSW26S info Integrate W26 x 0.706 Objective with RMS Mount RMS (0.800"-36) W26 x 0.706a
M25W26S info Integrate W26 x 0.706 Objective with M25 x 0.75 Mount M25 x 0.75 W26 x 0.706a
M32RMSS info Integrate RMS Objective with M32 x 0.75 Mount M32 x 0.75 RMS (0.800"-36)
M32M25S info Integrate M25 x 0.75 Objective with M32 x 0.75 Mount M32 x 0.75 M25 x 0.75
M32SM1S info Integrate SM1 Lens Tube with M32 x 0.75 Mount M32 x 0.75 SM1 (1.035"-40)
M32W26S info Integrate W26 x 0.706 Objective with M32 x 0.75 Mount M32 x 0.75 W26 x 0.706a
M32M27S info Integrate M27 x 0.75 Objective with M32 x 0.75 Mount M32 x 0.75 M27 x 0.75
M32M271S info Integrate M27 x 1.0 Objective with M32 x 0.75 Mount M32 x 0.75 M27 x 1.0
M32M32S info Integrate Large Diameter M32 x 0.75 Objective with Recessed M32 x 0.75 Mount M32 x 0.75 M32 x 0.75
M32M34S info Integrate M34 x 1.0 Objective with M32 x 0.75 Mount M32 x 0.75 M34 x 1.0
M32M40S info Integrate M40 x 0.706 Objective with M32 x 0.75 Mount M32 x 0.75 M40 x 0.706
M2M32S info Integrate M32 x 0.75 Objective with SM2 Mount SM2 (2.035"-40) M32 x 0.75
M2M34S info Integrate M34 x 1.0 Objective with SM2 Mount SM2 (2.035"-40) M34 x 1.0
M2M40S info Integrate M40 x 0.706 Objective with SM2 Mount SM2 (2.035"-40) M40 x 0.706
  • W26-threaded objectives are sometimes referred to as M26-threaded, but as long as the objective conforms to ISO 9345:2019 or JIS B 7141:2012, it will be compatible with our W26 adapters.

Thorlabs' Threading Specifications

Threading specifications are given below for our adapters so that you can machine mating components to suit your application. 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.


Click to Enlarge
RMS Threading
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"
M25 x 0.75 Threading
External Thread Internal Thread
Max Major Diameter 24.977 mm Min Major Diameter 25.000 mm
Min Major Diameter 24.837 mm Min Pitch Diameter 24.513 mm
Max Pitch Diameter 24.49 mm Max Pitch Diameter 24.659 mm
Min Pitch Diameter 24.379 mm Min Minor Diameter (and 83.3% of thread) 24.188 mm
Max Minor Diameter 24.165 mm Max Minor Diameter (and 64.9% of thread) 24.378 mm
SM1 Threading
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"
W26 x 0.706 Threading
External Thread Internal Thread
Max Major Diameter 25.930 mm Min Major Diameter 26.000 mm
Min Major Diameter 25.830 mm Min Pitch Diameter 25.580 mm
Max Pitch Diameter 25.520 mm Max Pitch Diameter 25.660 mm
Min Pitch Diameter 25.440 mm Min Minor Diameter 25.200 mm
Max Minor Diameter 25.070 mm Max Minor Diameter 25.300 mm
M27 x 0.75 Threading
External Thread Internal Thread
Max Major Diameter 26.977 mm Min Major Diameter 27.000 mm
Min Major Diameter 26.837 mm Min Pitch Diameter 26.513 mm
Max Pitch Diameter 26.49 mm Max Pitch Diameter 26.660 mm
Min Pitch Diameter 26.378 mm Min Minor Diameter (and 83.3% of thread) 26.188 mm
Max Minor Diameter 26.165 mm Max Minor Diameter (and 64.9% of thread) 26.378 mm
M27 x 1.0 Threading
External Thread Internal Thread
Max Major Diameter 26.95 mm Min Major Diameter 27.0 mm
Min Major Diameter 26.58 mm Min Pitch Diameter 26.35 mm
Max Pitch Diameter 25.0 mm Max Pitch Diameter 26.52 mm
Min Pitch Diameter 24.8 mm Min Minor Diameter (and 83.3% of thread) 25.917 mm
Max Minor Diameter 23.704 mm Max Minor Diameter (and 64.9% of thread) 26.153 mm
M32 x 0.75 Threading
External Thread Internal Thread
Max Major Diameter 31.977 mm Min Major Diameter 32.000 mm
Min Major Diameter 31.837 mm Min Pitch Diameter 31.513 mm
Max Pitch Diameter 31.49 mm Max Pitch Diameter 31.663 mm
Min Pitch Diameter 31.376 mm Min Minor Diameter (and 83.3% of thread) 31.188 mm
Max Minor Diameter 31.165 mm Max Minor Diameter (and 64.9% of thread) 31.378 mm
M34 x 1.0 Threading
External Thread Internal Thread
Max Major Diameter 33.974 mm Min Major Diameter 34.000 mm
Min Major Diameter 33.794 mm Min Pitch Diameter 33.350 mm
Max Pitch Diameter 33.324 mm Max Pitch Diameter 33.520 mm
Min Pitch Diameter 33.199 mm Min Minor Diameter (and 83.3% of thread) 32.917 mm
Max Minor Diameter 32.891 mm Max Minor Diameter (and 64.9% of thread) 33.153 mm
M40 x 0.706 Threading
External Thread Internal Thread
Max Major Diameter 39.969 mm Min Major Diameter 40.000 mm
Min Major Diameter 39.830 mm Min Pitch Diameter 39.542 mm
Max Pitch Diameter 39.511 mm Max Pitch Diameter 39.670 mm
Min Pitch Diameter 39.414 mm Min Minor Diameter (and 83.3% of thread) 39.236 mm
Max Minor Diameter 39.206 mm Max Minor Diameter (and 64.9% of thread) 39.405 mm
SM2 Threading
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"

Posted Comments:
Levin Hafa  (posted 2023-02-13 11:36:14.023)
Hi, Is it possible to receive a quote for an M34 external M25 internal adapter? Best regards Levin Hafa
Devin Porter  (posted 2022-03-07 20:37:54.29)
I have a nikon objective (M25 x 0.75 threading) that I am trying to use with a zeiss axiovert microscope (turret threading appears to be about 25 mm). Is there an adapter that we can use? Thanks, Devin
cdolbashian  (posted 2022-03-15 09:43:13.0)
Thank you for reaching out to us Devin. Threading in microscopy is often very specific to the model of the microscope and corresponding objective turret used. I have reached out to you to discuss the particular model of Zeiss Axiovert, and the objective threading therein. It is likely we do have a threading adapter for you although we first need to correctly identify the threading used on your microscope.
SANDEEP MISHRA  (posted 2021-08-03 16:02:35.0)
I want to use Olympus W20.32x0.706 (RMS) Objective to Nikon Microscope. Nikon objective have M25x0.75 thread. Please suggest the adapter for the same. Thanks
YLohia  (posted 2021-08-05 01:22:09.0)
Hello, thank you for contacting Thorlabs. Unfortunately, we currently do not offer an internal RMS to external M25 x 0.75 thread adapter. We will consider looking into offering such an item in the future.
Andres Medina  (posted 2020-09-15 17:54:32.807)
Hello. I'm looking for an adapter of 0.75 inch diameter to 1.0 inch diameter. The idea is to use Nikon objectives in a Zeiss microscope. Can you help me to decide which option is better? Thanks, Best regards, Andres Medina
YLohia  (posted 2020-09-18 02:28:21.0)
Hello Andres, thank you for contacting Thorlabs. Based on our direct discussion, in order to convert the M25 x 0.75 threads of the objective to the RMS threads of the microscope, you will need the RMSA2 adapter.
Tobias Noebauer  (posted 2020-08-31 21:00:44.693)
We keep having issues with this adapter getting stuck in a microscope objective thread. I think this is because of the two d=0.06in holes that go through the flange ring (the face with the markings). These holes have sharp edges on the opposite side of the flange ring, which get pressed against the microscope housing when the adapter is fastened. These sharp edges create extra friction that can get the adapter stuck quite firmly. Not even the spanner wrench tool can help in these situations, we have to use WD-40 and some special pliers. I would suggest not to drill these holes all the way through the flange ring but leave them blind. Thank you!
YLohia  (posted 2020-09-01 04:30:15.0)
Hello Tobias, thank you for your feedback. We're always looking for ways to improve our products, so any thoughts on such matters are always appreciated. I have posted your suggestions on our internal engineering forum for further consideration.
Back to Top

Adapters with External RMS (0.800"-36) and Internal Industry-Standard Threads

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
RMSW26S Support Documentation
RMSW26SBrass Microscope Adapter with External RMS Threads and Internal W26 x 0.706 Threads
$30.00
Today
Back to Top

Adapters with External M25 x 0.75 and Internal Industry-Standard Threads

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
M25W26S Support Documentation
M25W26SBrass Microscope Adapter with External M25 x 0.75 Threads and Internal W26 x 0.706 Threads
$30.00
Today
Back to Top

Adapters with External M32 x 0.75 and Internal Industry-Standard Threads

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
M32RMSS Support Documentation
M32RMSSCustomer Inspired! Brass Microscope Adapter with External M32 x 0.75 Threads and Internal RMS Threads
$27.81
Today
M32M25S Support Documentation
M32M25SCustomer Inspired! Brass Microscope Adapter with External M32 x 0.75 Threads and Internal M25 x 0.75 Threads
$23.30
Today
M32SM1S Support Documentation
M32SM1SCustomer Inspired! Brass Microscope Adapter with External M32 x 0.75 Threads and Internal SM1 Threads
$37.89
Today
M32W26S Support Documentation
M32W26SBrass Microscope Adapter with External M32 x 0.75 Threads and Internal W26 x 0.706 Threads
$30.00
Today
M32M27S Support Documentation
M32M27SCustomer Inspired! Brass Microscope Adapter with External M32 x 0.75 Threads and Internal M27 x 0.75 Threads
$30.08
Today
M32M271S Support Documentation
M32M271SBrass Microscope Adapter with External M32 x 0.75 Threads and Internal M27 x 1.0 Threads
$23.30
Today
M32M32S Support Documentation
M32M32S Brass Microscope Adapter with External and Internal M32 x 0.75 Threads
$52.19
Today
M32M34S Support Documentation
M32M34SCustomer Inspired! Brass Microscope Adapter with External M32 x 0.75 Threads and Internal M34 x 1.0 Threads
$44.26
Today
M32M40S Support Documentation
M32M40SCustomer Inspired! Brass Microscope Adapter with External M32 x 0.75 Threads and Internal M40 x 0.706 Threads
$46.59
Today
Back to Top

Adapters with External SM2 (2.035"-40) and Internal Industry-Standard Threads

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
M2M32S Support Documentation
M2M32SCustomer Inspired! Brass Microscope Adapter with External SM2 Threads and Internal M32 x 0.75 Threads
$69.62
Today
M2M34S Support Documentation
M2M34SCustomer Inspired! Brass Microscope Adapter with External SM2 Threads and Internal M34 x 1.0 Threads
$69.62
Today
M2M40S Support Documentation
M2M40SCustomer Inspired! Brass Microscope Adapter with External SM2 Threads and Internal M40 x 0.706 Threads
$69.62
Today
Additional Microscope Objective Accessories
  • Parfocal Length Extender for Microscope Objectives

  • Microscope Thread Adapters

  • Objective Storage Accessories

  • Microscope Immersion Oil