Cooke Lens Service

MOHR Lens Service repairs, services and recalibrates Cooke cinema lenses from a dedicated optical and CNC workshop in Solna, Stockholm, serving rental houses, owner-operators and cinematographers across Europe. As a Cooke-certified technician, I am trained across the range up to and including the S8/i primes and the Cooke anamorphics — the most mechanically demanding lenses in the lineup — and the newer compact series sit well within that scope. I also offer uncommon depth on the older glass that rental fleets send out for service: the Speed Panchros, early S4 primes and the Varotal zooms. All work is carried out by one person, start to finish, with nothing subcontracted out.

What I service on Cooke lenses

• Full CLA (clean, lubricate, adjust) on primes and zooms
• Parfocal calibration and back-focus / flange depth correction
• Cam and follower diagnosis and repair on Varotal zooms
• Focus and iris mechanism overhaul — smoothing, re-greasing, backlash removal
• Optical cleaning, separation and haze assessment
• Collimation on a vertical collimator
• Mount work and shimming (PL / LPL), flange face truing
• Custom part fabrication when factory spares are unavailable (CNC and lathe)

Cooke zooms — from Super 16 to the large-format Varotals

Cooke’s zoom range is wide, and across my career I have serviced examples of every Cooke zoom series I am aware of — from the Super 16 zooms, including several highly sought-after models, through the classic Super 35 Varotals (18–100, 20–60, 20–100 and 25–250) to the larger S35 and full-frame zooms such as the 40–400. I am also familiar with Technovision-modified Cooke optics, such as the faster 18–90 built from a modified 20–100 Varotal.

The Varotals are where most zoom service requests land, and where the hardest problems live. A zoom that has drifted out of parfocal — sharp at the wide end, soft when zoomed in — is usually not an optical fault but a mechanical one: cam indexing, worn cam follower rollers, or flange and shimming that has shifted over the years.

A recent Cooke 18–100 Varotal came in with a parfocal fault that traced back to a cam indexing misalignment rather than the optics. The repair involved correcting the indexing and fabricating replacement cam follower rollers from Duratron T4203 (PAI) rod stock on the lathe, since factory spares for this vintage are no longer available. The lens was returned holding focus across the full zoom range.

This is the kind of work that defines the service: diagnosing the real cause, and making the part when the spare no longer exists.

Cooke primes — from Speed Panchro to S8/i

Prime service is mostly CLA, focus and iris feel, optical cleaning and mount truing. The Speed Panchros and early S4s benefit from someone who has had many of them apart — grease choice and reassembly torque make the difference between a lens that feels factory-fresh and one that merely feels “serviced.”

Mount conversions and mechanical modifications

Beyond standard service, I design and fabricate mount solutions and carry out mechanical modifications — including work that sits in the borderland of rehousing. A common job is converting older mount types — Mitchell BNCR, Arri Standard, M42 and similar vintage mounts — to modern PL, with the back-focus and flange depth set correctly so the lens performs on current cameras.

I also install and calibrate modern mount adapters such as EF. Off-the-shelf adapters are widely sold, but fitting one so that back-focus and parfocal tracking are actually correct is not a simple swap — it is precision work. If you have an adapter and need it installed and properly calibrated, that is something I can help with.

Why send a Cooke to MOHR

• Cooke-certified, working solo — the person who quotes the job does the job
• Full CNC and lathe capability in-house for parts that no longer exist as spares
• Optical bench and vertical collimator for collimation and re-cementing work
• Based in Stockholm, serving rental houses and owner-operators across Europe

What I don’t do

Honest scope keeps the right work coming in. I do not take on full rehousing — stripping optics from their original barrel into a completely new cine housing is time-intensive, and others do it better; I am happy to point you toward specialists for that. Mount conversions, custom mount solutions and mechanical modifications, however, are very much part of the work — see above.