OLJ LM RINGS
Classic LTM Lens & Leica M Compatibility Guide
Bringing Classic Lenses to Leica M Cameras
A classic lens deserves to be used, not merely collected.
At OLD LENS JUNKIES, we believe even the smallest photographic accessory should respect the history, engineering, and character of the lens it supports.
Our L39-to-Leica M adapter rings allow compatible Leica Thread Mount (LTM) lenses to be mounted on Leica M cameras.
But which adapter should you choose? And why are there three different versions?
This guide explains the differences and provides a practical reference for photographers using classic Leitz, Nikon, Canon, ZUNOW, Fujinon, Voigtländer, and other historic LTM lenses.
1. Understanding the Three OLJ LM Rings
OLJ offers three conventional adapter types:
OLJ LM RingFramelines selected on a typical modern Leica M
28/90mm28mm + 90mm
35/135mm35mm + 135mm
50/75mm50mm + 75mm
The markings indicate which viewfinder framelines the ring selects, not the focal length of the adapter itself.
All three types provide the same nominal LTM-to-M registration difference of 1.0mm. Their frameline-selection profiles differ.
2. Leica M Camera Compatibility Reference
Not every Leica M camera displays the same framelines.
The following table identifies the frames selected by each OLJ adapter on standard,
unmodified camera viewfinders.
Leica M camera. 28/90 Ring. 35/135 Ring 50/75 Ring
Leica M2 90 35 50
Leica M3 50 + 90 50 + 135 50
Leica M4 90 35 + 135 50
Leica M5 90 35 + 135 50
Leica M4-2 90 35 + 135 50
Leica M4-P 28 + 90 35 + 135 50 + 75
Leica M6 (0.72×) 28 + 90 35 + 135 50 + 75
Leica M7 (0.72×) 28 + 90 35 + 135 50 + 75
Leica MP (0.72×) 28 + 90 35 + 135 50 + 75
Leica M-A 28 + 90 35 + 135 50 + 75
Leica M8 / M8.2 28 + 90 24 + 35 50 + 75
Leica M9 28 + 90 35 + 135 50 + 75
Leica M Typ 240 28 + 90 35 + 135 50 + 75
Leica M10 / M11 28 + 90 35 + 135 50 + 75
Important notes
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The Leica M3 always retains its 50mm frameline.
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The Leica M2 has no built-in 28mm or 135mm framelines.
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The Leica M8 has a special 24/35mm frame pairing and a smaller sensor than full-frame Leica M cameras.
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Certain 0.58× and 0.85× viewfinder versions offer different available framelines.
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Modified or special-production cameras may differ from the table.
3. Classic LTM Lens Reference Guide
The following list includes genuine or documented Leica Thread Mount versions of notable classic lenses.
Wide-angle lenses
Lens Recommended LM Ring
Voigtländer Super Wide-Heliar 15mm F4.5 LTM 28/90*
Voigtländer Color-Skopar 21mm F4 LTM 28/90*
Voigtländer Snapshot-Skopar 25mm F4 LTM 28/90*
Nikon W-Nikkor 2.5cm F4 LTM 28/90*
Leitz Hektor 2.8cm F6.3 28/90
Nikon W-Nikkor 2.8cm F3.5 LTM 28/90
Canon 28mm F3.5 LTM 28/90
35mm lenses
Lens Recommended LM Ring
Leitz Summaron 3.5cm F3.5 35/135
Leitz Summaron 35mm F2.8 LTM 35/135
Leitz Summicron 35mm F2 LTM (rare version) 35/135
Nikon W-Nikkor 3.5cm F1.8 LTM 35/135
Nikon W-Nikkor 3.5cm F2.5 LTM 35/135
Canon 35mm F2 LTM 35/135
50mm standard lenses
Lens Recommended LM Ring
Leitz Elmar 5cm F3.5 50/75
Leitz Summitar 5cm F2 50/75
Leitz Summicron 5cm F2 50/75
Leitz Summarit 5cm F1.5 50/75
Nikon Nikkor 5cm F2 LTM 50/75
Nikon Nikkor 5cm F1.4 LTM 50/75
Nikon Nikkor 5cm F1.1 LTM 50/75
ZUNOW 5cm F1.1 LTM 50/75
ZUNOW 5cm F1.3 LTM 50/75
Fujinon 5cm F1.2 LTM 50/75
Canon 50mm F1.2 LTM 50/75
Canon 50mm F1.4 LTM 50/75
Tokyo Kogaku Topcor 5cm F1.5 LTM 50/75
Portrait and telephoto lenses
Lens Recommended LM Ring
Leitz Hektor 7.3cm F1.9 50/75*
Voigtländer Color-Heliar 75mm F2.5 LTM 50/75
Nikon Nikkor 8.5cm F1.5 LTM 28/90*
Canon 85mm F1.9 LTM 28/90*
Leitz Summarex 8.5cm F1.5 28/90*
Leitz Elmar 9cm F4 28/90
Leitz Thambar 9cm F2.2 (original LTM) 28/90
Leitz Hektor 13.5cm F4.5 35/135
Leitz Elmar 13.5cm F4 35/135
An asterisk * identifies a focal length without an exact corresponding Leica M frameline. The ring recommendation is a practical selection, not a guarantee of precise optical framing.
Recommendations refer to the specified LTM versions. Physical fit, rear-element clearance, and rangefinder compatibility must be checked on the actual lens and camera.
4. Two Special Wide-Angle Classics
Leitz Hektor 2.8cm F6.3
Introduced in 1935, the Hektor 2.8cm F6.3 represents an important chapter in the development of Leica wide-angle photography.
Its compact construction and distinctive appearance make it particularly interesting to collectors of early Leitz equipment.
OLJ recommendation: 28/90mm LM Ring
On Leica M cameras with a 28mm frameline, this is the conventional selection.
On an original Leica M2, however, the 28/90 ring selects the 90mm frame. Photographers may alternatively prefer the 35/135 ring to display the M2's 35mm frameline as a rough reference. Neither provides exact 28mm framing.
Nikon W-Nikkor 2.5cm F4
Nikon's W-Nikkor 2.5cm F4 is a fascinating wide-angle lens with a Topogon-type optical design.
The lens was produced in both Nikon S-mount and Leica screw-mount versions, which must not be confused.
OLJ recommendation: 28/90mm LM Ring for the LTM version
The Leica screw-mount version has its own focusing helicoid and can be adapted to Leica M cameras using a suitable LM ring.
Because the lens has a 25mm focal length, no conventional 28mm frameline gives an exact representation of its field of view.
For accurate composition, an appropriate external optical finder or compatible digital live-view system is preferable.
5. Special Focal Lengths and Viewfinders
21mm and 25mm lenses
These focal lengths are wider than the usual 28mm frame. A 28/90 adapter is a conventional choice, but the viewfinder may require an external finder or live view.
73mm and 85mm lenses
The 50/75 and 28/90 rings respectively offer nearby frame selections on cameras that support them. These frames remain approximate.
Leica M2 and M3
These earlier cameras do not display all the framelines found on later Leica M models. Selecting an adapter based solely on its engraved focal-length marking may not result in a useful optical frameline.
Digital Leica M cameras with Live View or EVF
When composing through the sensor, the ring's frameline designation is not required for accurate composition. The optical viewfinder selection still matters when switching back to rangefinder viewing.
6. Frequently Asked Questions
Does an LM ring change the focal length of my lens?
No. The adapter changes the mount interface, not the lens's optical focal length.
Can I use a Nikon S-mount or Contax-mount lens with an OLJ LM Ring?
No. The lens must have the appropriate Leica LTM interface. Nikon S and Contax rangefinder lenses use different mounts.
Will the LM ring make an uncoupled lens rangefinder-coupled?
No. The adapter cannot add a rangefinder coupling mechanism to a lens that does not have one.
Can I use any of the three rings with Live View?
For framing, yes, provided that the ring, lens, and camera are mechanically compatible and the adapter provides correct registration. The displayed optical framelines will still differ.
Are all M39-threaded lenses Leica LTM lenses?
No. The Leica Thread Mount uses a specific thread and flange-distance standard. Other lenses described as M39 may have different specifications and are not automatically compatible.
What about collapsible LTM lenses?
Before collapsing any adapted lens, confirm that it will not contact the shutter, sensor assembly, or other internal camera components.
7. The Story Behind OLJ LM Rings — Project No. 11
The OLJ LM Ring project reflects our commitment to making thoughtfully designed accessories for classic photographic equipment.
We believe an adapter should complement a vintage lens without distracting from its original character.
Discover the development story behind Project No. 11, including our design approach and the reasons for producing three different ring versions.
OLD LENS JUNKIES
Embracing the Timeless Charm of Vintage Lenses.
Reference disclaimer: Lens listings describe historical LTM versions and nominal frameline selections. They do not constitute individual fit or focus-accuracy certification. Check unusual lenses and modified equipment before use.
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