Description

FZ–E Mount Conversion System

A Personal Project Turned Practical Solution for Rokinon Cine DS Lenses**

When I first bought my second-hand Sony F5, I quickly realized my lens options were limited. I was coming from Sony mirrorless bodies—cine cameras included—and all I had was native e-mount lenses and a full set of Rokinon Cine primes collecting dust. Naturally, I wondered whether I could bring these lenses over to the FZ platform. After comparing flange distances between Sony E-mount (18mm) and the FZ mount (19mm), and looking at the physical space around the F5’s sensor and mount, an idea started forming: if I could reclaim that 1mm difference mechanically, maybe these lenses could work.

Research showed exactly what I expected—nothing on the market did this. The only remotely similar option was the official Fujinon MK conversion kit. So I grabbed a micrometer, took some careful measurements, and drafted my first design in CAD. A friend ran a rough 3D print for me, I sanded it smooth, and after a few tweaks, the concept actually worked.

Once the geometry felt right, I sent the CAD files off to SendCutSend. A short time later, a small package arrived on my doorstep. After a quick trip to the hardware store for screws and basic fittings, I assembled a functioning (though admittedly rudimentary) prototype. To my surprise, every one of my Rokinon Cine DS lenses mounted cleanly—and after testing, I hit both minimum focus and infinity with no shims required.

I’ve continued refining the design through multiple iterations, testing, measuring, and adjusting, and now, after a lot of trial and error, I’ve decided to release the CAD files to the community.

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How It Works — Solving the Flange Depth Problem at the Source

Rather than stacking adapters or adding optical elements, this system replaces the metal E-mount ring on the lens with a custom-designed FZ ring. By physically shifting the lens 1mm closer to the sensor, the proper optical path is restored. Infinity focus is preserved, no shims are required, and the lens behaves exactly as it should.

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What You’ll Need

Because this is still technically a prototype project, you’ll need to source a few basic items to complete the build:

• Mounting hardware — three screws (and optionally nuts or bolts, depending on your setup). The outer ring is designed to be tapped, so you can thread it directly if you prefer a cleaner, more secure fit.

• Your choice of adaptor fabrication — you can 3D print the rings to test fit and verify spacing, or go straight to CNC machining for a more durable final version. Personally, I used SendCutSend for my metal parts, and the turnaround was quick and affordable.

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A Two-Piece Modular Design

To keep manufacturing straightforward and cost-effective, the system uses a two-piece assembly:

Outer Ring – The FZ Interface

• CNC-machined aluminum, modeled after the Sony FZ-to-PL adapter dimensions.
• Sits approximately 3mm inside the FZ mount, matching the geometry used by Sony’s own adapters.
• Affordable to produce: ~$14.65 for 5 units raw, $28.60 for 5 anodized.

Inner Ring – The Lens Mount Plate

• Drops into the outer ring from below and secures with three #4-40 screws.
• Designed specifically around the Rokinon Cine DS E-mount footprint.
• Height-adjustable to dial in precise flange distance using shims.
• The two rings together create a stable, rigid mounting platform with no optical compromise while reducing the lens flange distance by the required 1mm.

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Easy, Non-Destructive Installation

If you’ve ever swapped mount plates on lenses like the Fujinon MK series, the process will feel familiar:

1. Remove the three screws holding the original E-mount plate.
2. Lift it off and position the new inner ring.
3. Screw the inner ring into the outer FZ ring.
4. Mount your lens directly onto the FZ camera.

Everything remains reversible.

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Designed for the Rokinon Cine DS Set

Compatible with the entire Rokinon Cine DS E-mount lineup:

• 14mm
• 24mm
• 35mm
• 50mm
• 85mm

Each lens slots in securely and achieves proper focus travel.

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From Personal Experiment to Community Resource

This project started because I wanted to use the glass I already owned on a camera I fell in love with. It turned into weeks of tinkering, redesigning, and testing—and now it’s something I’m excited to share with anyone who wants to expand their FZ-mount lens options.

So here it is:
An open, accessible adapter design for filmmakers, tinkerers, and FZ-mount enthusiasts.
Take it, build on it, improve it, and make it your own.

If you want the links, I have uploaded it all to TinkerCAD and made it available there.
https://www.tinkercad.com/things/g3y7mtAkSNy-fz-mount-outer-ring-master
https://www.tinkercad.com/things/iAIqFIuaJx7-fz-mount-inner-ring-master-template
https://www.tinkercad.com/things/5UH9pIzzhFH-inner-shims