Introducing the Skyllaney: 50mm f/2 ‘Bertele’.
Skyllaney Opto-Mechanics is hard at work developing thier new 50mm f/2 Bertele lens. By 2021, we hope to release our first limited edition run of a 50mm f/2 classic Sonnar formula lens in native M bayonet, which optically is based very closely off the1937 pre-war era design by Dr Ludwig Bertele.
Our version contains the same element radii that were established by the good Doctor in 1937, but marries them with modern AR coatings which have increased contrast and reduced flaring. We also are implementing a 9 bladed 1937 sytle rounded aperture for enhanced bokeh, a high precision brass helicoid, 90-100 degree focus swing from 0.7m to infinity, a high-speed focusing body utilising a finger tab, all kept in a compact body no larger than the v4 cron. It will be initially offered in black anodised (6061 Aluminium) or chrome (Brass) finishes, with an initial run of 150 lenses, with possibly another 100 to follow. Each one will have the front filter ring customisable by the customer with up to 18 characters, in addiiton to ‘ Bertele 50mm f/2’ and the lenses limited run serial number.

The optical blocks containing the lens elements with modern AR coatings and the 9-bladed 1937 aperture design, are already at our workshop. We have 170 initial sets. They currently are undergoing testing against other sonnar formula lenses such as the Zeiss-Opton’s, Jupiter 8’s, Zeiss Jena’s and Cosina C-Sonnar, and plan to be included in our ‘Big Sonnar Review’. At the moment, they are performing very close to the 1937 Jena originals, with the added benefit of higher contrast, punchier colours and greatly increased flare resistance, due to the AR coatings.
The high precision mechanical bodies are still a work in progress, as we want to be sure we get it right the first time, not rushed. Of the initial 170 sets we have now, 20 of them are being used for pre-release prototype purposes. A few of these plan to be given to certain photographers to use in the field and provide us with feedback. After everyone involved is happy, we will then finalise the design and begin the production manufacturing runs.

Many parts of the lens, final assembly, engraving, testing, calibration and collimation is all performed here in England, with each final specimen being checked then by our chief Opto-Mechanical Engineer. Pending the success of our first lens, we look to do a limited run of at least one new lens design each year going forward.  

There are already discussions amongst our team about what that next lens might be. At the moment, we plan on either doing an ultra-compact 28mm or a 85mm f/1.4 portrait lens, either would be native M mount also. The portrait lens would be early Planar formula based (simliar to the Contax version), while we are interested to see if a 28mm Sonnar derivative lens could be designed sucessfully. We know Mizakisan struggled with this, and maybe we will also have to abandon this hope, but we shall have to wait and see.  Ideally, our ultra-compact 28mm would be between f/2 to f/2.8 aperture, no larger then a M mount bayonet cap when mounted on the cameras, and ofcourse include a finger tab for quick focusing.

Lastly, we are exploring what we call the ‘Super Sonnar’ project. It would be a 50mm f/1 Sonnar formula lens, that would include an FLE in a certain strategic location to eliminate the Sonnar focus shift. Two of us on our team made some early discoveries about Planoconvex lenses being used on rangefinder wide-angle lenses to eliminate aberrations and field curvature on thick filter glassed digial sensors. A few years ago, a photographer in Japan named HaruhikoT discovered that placing optical laser correction filters on Contax G lenses, the field curvature and incorrect dispersion of light in the corners, which was causing corner smearing, could be almost entirely eliminated with the addiiton of a front correction lens. When we read this, we procured plano-convex lenses ourselves made by OptoSigma, Ekspla and Zeiss, and began to place them on the near full sets of Zeiss ZM and Voigtlander VM lenses we had in our personal collections. The Plano-Convex and Proxar lenses (also known as close up filters) were found to work exceptionally well, once the key correction strength needed, was optimally determined.

From early experiments with correction lenses, we had learned that adding an element to existing optical formulas in strategic locations could make previously unusable lenses on various manufacturers digital cameras, usable. We then began to explore if a floating correction lens element could be used to cure the Sonnar focus shift, without negatively affecting its rendering.

The Super Sonnar lens would have its central 25% of the image frame sharp wide open, but leave the natural spherical aberrations present on purpose, to ensure the sanctity of the sonnar bokeh remain.
We have been careful to design and implement the FLE not to remove the character of the Sonnar formula, but enable the shift from that formula to be taken merely under our control. 

Without an FLE, a Super Sonnar formula lens, calibrated to focus accurately at say f/1.0 wide open across the range, would shift too much due to its spherical aberration reduction in the outer edges of the lens elements as the lens stops down, aperture wise. A pointed (ninja star) type of aperture could partialy compensate for this, but then the pointed aperture would have other adverse effects on the lenses bokeh. The focus shift theoretically would be massive by the time the formula is finished, possibly having the lens go soft by f/2.8 and not return sharp until DOF catches up at f/8. This is not too big of an issue on cameras that have through sensor image feeds (live view and EVF), where aperture specific re-focusing can take place. However, the rangefinder has no way of compensating for focus shift between apertures. So, if we want our Supper Sonnar formula lens to be f/1, and we want it usable by rangefinder users across its aperture, we have to go down the FLE route.

We already have early designs for this Super Sonnar lens and are trying to keep the computations as close to some optical diagrams we studied that Dr. Ludwig Bertele created in the late 1930’s onward. Using CAD, written calculations and ray-tracing software, we’ve been extrapolating out these old formulas to create a computation that is merely a two stops faster version of the original collapsible 5cm f/2 Jena. At the same time, we are mindful in ensuring the formula does not become too large also in that process, considering we are attemptiong to incorporate an FLE also to manage the formuals focus shift. A design constraint of no heavier then 475g has been set, but already the front element has been calculated to be between 58-61mm in diameter if we want an actual f/1.0 lens. This is porbably why other manufactueres have choosen f/1.1 or there abouts, which drops a few millimeters off the front element set diamters. To offset the optical elment weight, lightweight aircraft aluminium, similar to the MS Optics ISM 50mm f/1.0, plans to be utilised.

Two of us on the team have this MS Optics lens already, and we are amazed how small they have gotten it, though we can see also by using the rotating element design with sloped CAM, they were able to save on things like fork sliders, thus reducing space. 

Our design is planned to be a non-rotating front, no different as to how the original f/1.0 Noctilux works.  

Limited run boutique lenses became an idea from seeing other companies, such as MS-Optics, do well in this area. We are more inspired by Mizakisan than anything else and would like to see other small manufacturers enter into this market . All of us have great respect for Mizakisans’s work, and it is why we believe we could also begin to design lenses in small batches that were made to high-quality standards, and succeed at this.

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14 Comments on “The 50mm f/2 ‘Bertele’”

  1. Pingback: Skyllaney is a new lens manufacturer in England and they just released their first Bertele 50mm f/2 lens for Leica M-mount - Leica Rumors

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