Skyllaney Opto-Mechanics now offers the ability to convert non-rangefinder lenses to M bayonet with full RF coupling from 0.67m to Infinity using the Omnar.

The Omnar is capable of converting optical blocks from 8mm to 52.4mm in focal length. Lenses like the 42mm Summar, 50mm Sonnar, 28mm Tessar, 35mm Biometar, 40mm Rollei, 21mm Biogon and countless others can be now be converted to have:

  • Reverse engineering the optical block to extract the true EFL value of the lens formula, and design of the adaptation mechanics to rehouse the lens into the Omnar device.
  • RF coupling from 0.67m to Infinity for M, VM and ZM bayonet rangefinder cameras.
  • A high precision, all brass helicoid system designed and manufactured here, in the United Kingdom.
  • Laser engraved focus ring with your choice of metric or imperial distance increments.
  • All brass finger tab.
  • A cleaning, lubrication, and adjustment (CLA) of your existing optical block (note: removal of fungus, removal of haze, ultrasonic cleaning of oil drenched aperture blades are an additional costs).
  • 1 Year warranty on all parts and work.
  • A choice of Antique Brassing, House Black Matte or House Gloss Black on the new conversion parts (does not include re-paint of existing parts on the optical block such as aperture rings).

Professional full lens re-paints through Camerakote of Staffordshire, England are available at an additional cost and a full range of colours. See some examples below.

Typical lens conversion examples, see below:

Carl Zeiss Jena 2.8cm f/8 Tessar – Omnar conversion
Nikkor-S.C 5cm f/1.4 Nippon Kogaku – Omnar conversion
Carl Zeiss Jena 5cm f/1.5 “nickel” Sonnar – Omnar conversion

Omnar conversion prices start at 1,249 GBP and include your choice of in-house finishes. Certain optical blocks that require complex engineering solutions to facilitate the conversion cost extra. Conversions into Omnar currently require 8-12 weeks turn around time from receipt of your lens.

If you’re interested in converting your lens or have any questions, please contact us at or go to our Contact Us page:

Important information

Optical block requirements:

  • The optical block is no larger than 30mm in outer diameter towards the rear element set.
  • The optical block contains an aperture control ring if there is an adjustable aperture inside the lens.
  • The optical block is no heavier than 500g.

Optical block limitations:

The following lenses have a rear element that exceeds 30mm in diameter and CAN’T be converted using Omnar:

  • 35mm Pre-ASPH Summilux
  • Contax G 35mm Planar

Contax G lenses:

We are working on converting the Contax G 21mm and 28mm Biogons into Omnar. These lenses require new aperture control assemblies designed for the optical block. Conversions for these lenses will be available at a later date. You can contact us to be added to a waiting list.

Point and Shoot lenses:
Point and Shoot (P&S) camera lenses like the Contax T2 38mm Sonnar, Yashica T 35mm Tessar, Nikon 28mm AF600 require new aperture controls designed and fabricated to facilitate conversion into Omnar.
These are currently in design, and will be offered in batches exclusively through the Omnar Lenses website.  If you have a P&S camera lens, please subscribe to the Omnar Lenses mailing list to be notified of when the 38mm Sonnar, 35mm Tessar and 28mm AF600 conversions are announced.

Effective Focal Length:
It should be noted that the advertised focal length of a lens (such as 28mm, 35mm, 50mm) is not its true focal length. Often the true focal lengths might be 51.6mm, 52.4mm, 49.5mm, 37.5mm, 34.6mm, 29.2mm, 27.5mm, etc. 

These true focal length values are known as the ‘Effective Focal Length’ (EFL) of a lens formula. On certain Leica manufactured lenses, the EFL modifier value is found to the right of the infinity symbol.

Leica 90mm Tele-Elmarit shown above

Thus, a Leica 90mm lens with a 05 next to the infinity symbol, indicates the lenses EFL is actually 90.5mm.

To ensure the RF coupling is accurate across the focus range, this true EFL value needs to be extracted from the optical formula.  For a Carl Zeiss Jena 50mm Sonnar lens, the EFL value is 52.4mm. For a Contax T2 38mm Sonnar, the EFL value is actually 37.5mm.
One size fits all RF cam slopes for 35mm, 50mm lenses are not possible, as even a minor 0.1mm EFL deviation between the RF cam and the optical formula will cause focus accuracy issues.  This is often why certain conversions and lower costing rangefinder lenses struggle to focus accurately at both infinity and 0.67m MFD, as the RF cam and optical formula EFL are not exactly matching each other due to the usage of a generic RF cam which is not tuned for that specific lens formula’s EFL. The tuning of the optical formula to the RF cam can sometimes be a long and drawn-out process which requires either the RF cam slope to be adjusted to match the optical EFL, the secondary helicoid thread pitch to be changed, or the optical EFL modified to match the RF cam.

When the critical EFL value between RF cam and optical formula is in a state of mismatch, front or back focusing at either the near or far field becomes exhibited.
No doubt this is why Leica lenses cost what they do, as the quality control, optical centering, and helicoid to optical block EFL calibrations are checked on each specimen.

The powered by Omnar conversions go through this same process, ensuring your lens focuses accurately and the sub-optical block is centered correctly within the Omnar device.

2 Comments on “Conversions (powered by Omnar)”

  1. On Facebook recently,there was news of a new ltd.edition conversion offer.
    Converting Nikon sc 50/1.5 Sonnar to full Leica M coupling.
    I am very interested in this project.I have an unused recent reissue of this lens I would like to have converted.

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