Canon Mount Adapter EF-EOS R 0.71x

The Canon Mount Adapter EF-EOS R 0.71x is a specialized optical focal reducer designed for using compatible full-frame Canon EF lenses on the Super 35mm Canon EOS C70.

Unlike a standard mechanical adapter, its 0.71x optical system concentrates the full-frame lens’s image onto the smaller Super 35mm sensor. This restores an angle of view similar to the lens’s full-frame perspective while increasing light transmission by approximately one stop.

⭐ Key Benefits

• Designed specifically for the Canon EOS C70

• Mounts compatible full-frame EF lenses to the camera’s RF mount

• 0.71x optical focal reduction

• Maintains an angle of view similar to full-frame

• Increases light transmission by approximately one stop

• Supports Dual Pixel CMOS AF with compatible lenses

• Supports automatic exposure and electronic iris control

• Transfers lens and shooting metadata

• Supports compatible optical corrections

• Secure four-screw mounting system

• Upper and lower locking plates included

• Compact cinema-oriented design

🎥 Designed for the EOS C70

The 0.71x adapter was developed around the EOS C70 and its Super 35mm Dual Gain Output sensor.

It should not be treated as a general-purpose focal reducer for EOS R still cameras. Canon specifies it for supported EOS C70 and full-frame EF lens combinations.

The adapter’s included support plates fasten directly to the C70, providing a more secure connection for production use than relying on the RF mount alone.

🔭 Maintain a Full-Frame-Like Angle of View

A full-frame EF lens normally produces a narrower angle of view when mounted in front of a Super 35mm sensor. The 0.71x adapter optically reduces the image to offset that crop.

For example:

This is particularly useful when matching the C70 with full-frame A-cameras or preserving the intended field of view of wide-angle EF lenses.

🌙 Approximately One Stop More Light

By concentrating the lens’s image onto the Super 35mm sensor, the adapter increases light transmission by approximately one stop.

Examples include:

The lens’s physical aperture does not change, but the concentrated image is approximately one stop brighter at the sensor.

This provides advantages for:

• Low-light documentary work

• Interviews using available light

• Weddings and live events

• Night exterior scenes

• Faster shutter speeds

• Lower ISO settings

• Shallower full-frame-style depth-of-field rendering

✨ Four-Element Optical System

The adapter uses an optical reduction group rather than operating as an empty spacer.

Its 0.71x magnification concentrates the larger image circle of a full-frame EF lens onto the C70’s Super 35mm sensor. The optics are designed to preserve sharpness and minimize unwanted aberrations with approved lens combinations.

For full correction and electronic compatibility, both the EOS C70 and adapter should use current firmware.

⚡ Dual Pixel CMOS Autofocus Support

Supported electronic EF lenses can retain Canon Dual Pixel CMOS autofocus through the adapter.

Depending on the approved lens, available functions may include:

• Continuous autofocus

• Face detection

• Eye detection

• Subject tracking

• Touchscreen focus selection

• Electronic manual-focus assistance

• Focus Guide

• Automatic iris control

Cinema primes with fully manual focusing and aperture rings remain manual, although compatible lens metadata and focus-assistance functions may still be available.

📡 Lens Metadata and Electronic Communication

The adapter carries supported lens information between the EF lens and EOS C70.

This can include:

• Lens identification

• Focal length

• Aperture or T-stop information

• Focus-distance data

• Autofocus commands

• Electronic iris control

• Image-stabilization communication

• Recorded clip metadata

Displayed and recorded focal-length and aperture information are corrected to account for the adapter’s optical effect on supported combinations.

🖼️ Compatible Optical Corrections

With approved EF lenses and current firmware, the EOS C70 can apply supported corrections for:

• Peripheral illumination

• Vignetting

• Lateral chromatic aberration

Correction availability depends on whether Canon has supplied a profile for the exact lens and adapter combination.

An unsupported lens may still mount physically but may not receive complete autofocus, metadata or correction support.

🎬 Excellent for Multi-Camera Productions

The adapter helps an EOS C70 produce framing closer to that of a full-frame Cinema EOS or hybrid camera using the same EF lens.

This makes it useful when pairing the C70 with cameras such as:

• Full-frame Cinema EOS cameras

• Canon EOS R5 C

• Other full-frame production cameras using EF lenses

Matching angle of view can simplify lens selection and help maintain more consistent visual language across a production.

🔒 Secure Locking Plates

Two included locking plates secure the adapter to the EOS C70 using four screws.

This additional support helps reduce movement between the camera, adapter and lens when using:

• Cinema lenses

• Follow-focus systems

• Lens motors

• Matte boxes

• Shoulder rigs

• Gimbals

• Other production accessories

The plates should be installed according to Canon’s instructions before using heavier lenses or accessories that place torque on the mount.

📋 Supported Lens Types

The adapter is intended primarily for selected full-frame Canon EF and EF-mount Cinema EOS lenses.

Supported models include selected lenses from categories such as:

• Canon EF L-series primes

• Canon EF L-series zooms

• Canon EF telephoto zooms

• Canon CN-E Cinema Primes

• Selected Canon Flex Zoom lenses in EF mount

• Selected Canon Cine-Servo lenses

The compatibility list has expanded through EOS C70 and adapter firmware updates. Compatibility should be confirmed for the exact lens rather than assumed from the EF mount alone.

⚠️ Important Compatibility Limitations

The Mount Adapter EF-EOS R 0.71x is not the same as Canon’s standard EF-EOS R adapters.

It is not intended for:

• General EOS R still cameras

• Canon EF-S lenses

• Canon RF or RF-S lenses

• Canon EF-M lenses

• Canon FD lenses

• Unapproved third-party EF lenses

• Mounting RF lenses to EF cameras

• Use as a teleconverter

EF-S lenses already project a smaller image circle and are not appropriate for the adapter’s full-frame optical reduction.

📋 Technical Specifications

📸 Ideal For

• Canon EOS C70 owners

• Professional filmmakers

• Documentary crews

• Wedding and event filmmakers

• Commercial productions

• Multi-camera productions

• Owners of full-frame Canon EF cinema lenses

• Owners of compatible EF L-series lenses

• Filmmakers requiring wider framing on Super 35mm

• Productions needing approximately one stop more light

• C70 users matching full-frame camera coverage

🆚 0.71x Adapter vs Standard EF-EOS R Adapter

Choose the standard adapter when a simple, non-optical EF-to-RF connection is required. Choose the 0.71x adapter specifically for supported EOS C70 productions that need full-frame-style coverage and increased light transmission.

🆚 0.71x Adapter vs Control Ring Adapter

The Control Ring Mount Adapter provides a customizable exposure ring and contains no optical elements. It preserves the normal Super 35mm crop when used on the EOS C70.

The 0.71x adapter does not add a control ring. Instead, it changes the optical projection to restore wider framing and provide approximately one additional stop of light.

🆚 0.71x Adapter vs Native RF Lenses

Native RF lenses mount directly to the EOS C70 and may offer:

• More compact designs

• Modern autofocus systems

• Native camera-to-lens communication

• RF control rings

• Advanced stabilization

• No additional mounting hardware

The 0.71x adapter is valuable when a production already owns compatible full-frame EF glass or needs to match the lens coverage of a full-frame camera.

📦 In the Box

• Canon Mount Adapter EF-EOS R 0.71x

• Front Adapter Cap

• Canon RF Rear Lens Dust Cap

• Upper Locking Plate

• Lower Locking Plate

• Mounting Screws

• Installation Tool

• Manufacturer documentation

🎒 Recommended Kit Additions

Consider pairing the adapter with:

• Canon EOS C70

• Compatible full-frame Canon EF lens

• Current EOS C70 and adapter firmware

• Lens support for heavier cinema lenses

• 15mm rod system

• Follow-focus system

• Matte box

• Production monitor

• High-capacity batteries

• High-speed SD cards

• Padded adapter and accessory case

🏬 Why Buy from Cameragraphics?

Cameragraphics is an authorized Canon dealer staffed by professional photographers and imaging specialists who can help verify EOS C70 and lens compatibility.

We can explain the difference between a standard adapter and a 0.71x focal reducer, confirm expected field of view and help build a properly supported Cinema EOS configuration.

Cameragraphics — Serving Auburn Since 1974.