The Story Behind OLJ LM Rings — Project No. 11
Three Rings, One Purpose — Understanding L39 to Leica M Adapters
For photographers who enjoy classic Leica screw-mount lenses, an LM adapter ring is a small but essential accessory.
It allows vintage L39 screw-mount lenses to be used on Leica M-mount cameras, opening the door to decades of photographic history.
But why are there three different LM rings, marked 28/90, 35/135, and 50/75?
Why Three Different Rings?
The answer lies in the Leica M optical viewfinder.
When a lens is mounted on a Leica M camera, the adapter's bayonet profile determines which set of frame lines appears in the viewfinder.
The three conventional LM rings are:
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28/90mm: For 28mm and 90mm lenses.
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35/135mm: For 35mm and 135mm lenses.
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50/75mm: For 50mm and 75mm lenses.
These markings identify the frame-line selection, not a difference in the ring's optical performance.
OLJ LM Ring Compatibility Guide
Not all vintage L39 lenses follow the standard Leica M focal lengths. Some classic lenses use unusual focal lengths such as 25mm, 40mm, 60mm, or 85mm.
The following guide helps you select the most suitable OLJ LM Ring based on your lens focal length, with examples of famous vintage lenses.
Focal Length OLJ LM Ring Famous Vintage Lens Examples
12–21mm 28/90* Voigtländer Super Wide-Heliar 15mm F4.5, Color-Skopar 21mm F4
24–25mm 28/90 Voigtländer Snapshot-Skopar 25mm F4, W-Nikkor 2.5cm F4
28mm 28/90 Leica Hektor 2.8cm F6.3, Canon 28mm F3.5
35mm 35/135 Leica Summaron 3.5cm F3.5, Leica Summicron 3.5cm F2, W-Nikkor 3.5cm F1.8
40mm 35/135 Voigtländer Nokton 40mm F1.4 (M-mount; not L39)
45mm 50/75 Selected vintage 45mm L39 lenses
50mm. 50/75 ZUNOW 5cm F1.1 LTM, Leica Summicron 5cm F2, Leica Summitar 5cm F2, Canon 50mm F1.2, Nikkor 5cm F1.4
55–60mm 50/75 Selected vintage 55mm, 58mm and 60mm L39 lenses
75mm 50/75 Voigtländer Color-Heliar 75mm F2.5
80–85mm 28/90 Nikkor 8.5cm F1.5 & F2 LTM, Canon 85mm F1.9,
Leica Summarex 8.5cm F1.5
90mm 28/90 Leica Elmar 9cm F4, Leica Thambar 9cm F2.2
100–105mm 28/90 Selected vintage 100mm and 105mm L39 lenses
135mm 35/135 Leica Hektor 13.5cm F4.5, Leica Elmar 13.5cm F4
For focal lengths wider than 28mm, an external viewfinder, EVF, or Live View is recommended for accurate composition.
Important Notes
Using an Optical Rangefinder (RF)
Choose the OLJ LM Ring that activates the most suitable available frame lines on your Leica M camera. For non-standard focal lengths, the frame lines provide approximate framing only.
Using an Electronic Viewfinder (EVF) or Live View
If you compose exclusively through an EVF or Live View, you do not need to worry about the ring's frame-line designation. Any of the three OLJ LM Rings can be used for framing, provided the lens and camera are mechanically compatible.
Lens Mount Compatibility
OLJ LM Rings are designed for compatible Leica L39 screw-mount lenses. Nikon S-mount, Contax-mount, and other lens systems require different adapters.
Remember that the available optical frame lines vary depending on the Leica M camera model.
The actual frame lines available depend on the Leica M camera model. For example, the Leica M3 does not have built-in 28mm or 35mm frame lines, while later models offer different combinations.
What If You Use an EVF or Live View?
Here is something many photographers may not realize.
If you compose exclusively through an electronic viewfinder (EVF) or Live View, you generally do not need to worry about which LM ring designation you use.
Whether your lens is 28mm, 35mm, 50mm, or 90mm, any of the three correctly manufactured LM rings can be used, provided the lens and camera are mechanically compatible.
This is because an EVF or Live View displays the actual image captured through the lens rather than relying on optical frame lines.
The adapter does not change the focal length or magnification of the lens.
For photographers using a Leica M240, M10, M11, or other compatible digital cameras with EVF or Live View, this provides welcome flexibility.
However, if you regularly switch back to the optical rangefinder viewfinder, choosing the matching ring remains preferable.
What About Ultra-Wide-Angle Lenses?
Classic L39 lenses with focal lengths such as 21mm, 24mm, or 25mm present another interesting case.
Most Leica M optical viewfinders do not provide dedicated frame lines for these focal lengths.
Photographers typically use an external optical viewfinder, EVF, or Live View for accurate composition.
Therefore, the choice between the three LM rings becomes less important for framing with these lenses.
Why OLJ Decided to Make Its Own Rings
At Old Lens Junkies, we believe that even the smallest accessory deserves thoughtful design.
For Project No. 11, we selected brass construction with a silver finish and distinctive OLJ JAPAN engraving.
Our aim is to provide a traditional appearance that complements classic Leica, Nikon, Canon, ZUNOW, and other historic L39 lenses.
Three versions are planned to cover the conventional Leica M frame-line combinations.
For the dedicated rangefinder photographer, choosing the correct ring preserves the intended optical viewfinder experience.
For the EVF or Live View photographer, the choice is much simpler.
A Note About Non-Standard Focal Lengths
Vintage lenses do not always follow modern standard focal lengths.
For example, a 25mm lens can use the OLJ 28/90 ring, an 85mm lens can use the 28/90 ring, and a 60mm lens can use the 50/75 ring.
These recommendations provide the closest conventional Leica M frame-line selection, not necessarily an exact view of the final photograph.
If you use an EVF or Live View exclusively, any of the three OLJ LM rings will work for framing, regardless of focal length.
Please ensure that your lens has a compatible Leica L39 screw mount. Nikon S-mount, Contax-mount, and other lenses require different adapters.
An LM ring selects frame lines; it does not convert other lens-mount systems or add rangefinder coupling to lenses that lack it.
Sometimes, understanding a small accessory can make a big difference in enjoying a vintage lens.
Old Lens Junkies — Embracing the Timeless Charm of Vintage Lenses!
