EF/GFX Lens Adapter

About adapter

Since the initial release of EF/GFX adapter, we have four models of adapter design, aims at better building quality and more convenience to our customers, the major differences are listed below, PRO edition and Gen III are in production now, and available for ordering.





Mounted on GFX 100s


EF/GFX PRO edition
Added Control Ring
Redesign, with rubber band in the rear mount
Quick release plate for Tripod mount
Initial product offering

Table 1 EF/GFX model differences

Function differences across different models since official firmware 3.03 release as following:

  • EF/GFX Gen. III
  • EF/GFX Gen. II
  • EF/GFX Gen. I
PDAF EXIF Recording
Distortion and TCA correction
Aperture Control Ring
Manual Focus Ring
Automatic focusing bracketing
Firmware update over USB and APP
USB storage disk firmware update
Buy NowBuy NowNot AvailableNot Available

Table 2 EF/GFX feature differences

NOTE: PDAF and Lens Correction Profile not available to all EF lenses yet, added gradually via firmware updates.

About Lens Working Modes

From official 3.03 firmware release, all EF/GFX supports two working modes, first is adapter mode, second is FUJIFILM GF lens simulation mode, can be switched by long pressing of MFB ( multifunction button) when adapter/lens are mounted, and camera is powered on already.

Features / Modes
Adapter mode
GF Lens simulation
35mm Auto Clipping
On when enabled in camera menu
Off always
LCP for in-camera JPEG
TCA is on, Distortion is off
TCA is on, Distortion is on
Good performance
Poor performance for telephoto lens
Focus bracketing
Disabled, except GFX 100
Enabled, AFB is available to PRO edition

Table 3 Differences between Adapter and GF Lens Simulation mode

FUJI Lens Mode Switch Simulation

FUJIFILM GF lens support mode C (Aperture priority by camera command dial) , mode A (Programming auto mode by camera) and Aperture dial mode.

For Steelsring EF/GF I/II/III adapters, with the help of short click of adapter’s MFB (multi-function button), it is able to simulate the mode switch simulation between C and A modes. initial mode simulation is mode C.

For PRO edition, with the add-on control ring in aperture body, it is possible to simulate an aperture dial too, the mode will cycle in C->A->Aperture Dial for PRO edition via short click of MFB, initial mode simulation for PRO edition is aperture dial instead of C for I/II/III adapters.

Lens mode switch simulation works always, is not relevant to adapter’s working mode as Adapter or GF lens simulation.

About MFB(multi-function button)

  • Activate firmware update mode for I/II/III and PRO adapters.

Press and hold MFB, then connect to PC/MAC via USB cable, then release the button will enable adapter enter firmware update mode.

  • When mounted on camera body with lens combination, after camera power on normally
    1. Short click MFB once, will start lens mode switch between C and A for I/II/III adapter, or C->A->Aperture dial for PRO adapter.
    2. Press and hold MFB for 5 secs or longer, then release MFB, will trigger adapter’s mode switch between Adapter mode and GF lens simulation mode, camera body will reboot EF/GFX adapter to be effective immediately.

About Lens Correction Profile

About PDAF

About Manual Focus Ring (PRO edition only, not available for I/II/III adapters)

When lens mode switch simulation is in C or A mode, aperture control is done via camera body dial, then we use the control ring to simulate a manual focus ring, it is more like power focusing of curtain EF lenses. To be effective, lens body AF/MF mode switch must be set to AF, and camera body focus mode dial set to MF. Turning control ring, it will activate camera’s MF assistant automatically.

About Automatic Focus Bracketing (PRO edition only, not available for I/II/III adapters)

When PRO adapter’s control ring can function as manual focus ring, it is able to set the begin and end positions of auto focusing bracketing depth now. So before entering Auto Focusing bracketing setting in camera body menus, please make sure adapter’s lens mode switch simulation is in C or A mode, and set Lens body AF/MF mode to AF, then turn the adapter’s control ring to set the position accordingly. Please do not turn lens body’s manual focus ring, it is useless because lens won’t report any distance change after focusing position changed, but FUJI’s algorithm need that value.

After finishing automatic focus bracketing positioning setting, control ring can be set to aperture dial simulation again.


  1. How to tell the current working mode of adapter?

In camera body menu for 35mm clipping, set it to Auto On. If you see a 35s logo in your EVF, then you are in adapter mode, otherwise it is in GF lens simulation mode.