Fringer Contax 645 User manual

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Fringer Contax 645 –Fujifilm GFX50s
Smart adapter user’s manual
(v2.0)
Important! Please read this manual carefully before using the adapter. Be noted:
The activation process is NOT required anymore. You can use the adapter on
your camera directly. Thus, G.CAP (the device for activation) is no longer
provided with the adapter.
1. General descriptions
This adapter is compatible with Contax 645 and Fujifilm G mount protocols. It can control
lens’ aperture electronically, auto focus (some of C645 lenses only) and support Exif recording.
All C645 lenses are supported. See the table below.
Contax 645 lenses
AF supported (Firmware v2.0)
Distagon T* 3,5/35
Y
Distagon T* 2,8/45
Y
Distagon T* 3,5/55
N
Planar T* 2/80
Y
Apo-Makro-Planar T* 4/120
N/A
Sonnar T* 2,8/140
Y
Sonnar T* 4/210
N
Tele-Apotessar T* 4/350
N
Vario-Sonnar T* 4,5/45-90
N
Sonnar T* 2,8/140 + Mutar 1,4x T*
Y
Sonnar T* 4/210 + Mutar 1,4x T*
N
Tele-Apotessar T* 4/350 + Mutar 1,4x T*
N
The adapter has been tested on GFX50s camera body. Theoretically it may support future G
mount bodies.
Please be noted that so far AF is an experimental feature. On one hand, not all lenses support
AF. On the other, even for those lenses supporting AF, the performance may not be good enough
for you. If the AF speed or accuracy can’t satisfy you, please change to MF mode. All lenses can
work under MF mode.
2. Installation and activation
I suggest connecting the lens with the adapter first. After that, install the adapter onto the
body. If you need to separate the lens from the adapter while the adapter is connected with the
body, you must turn off power first.
Although Fujifilm G mount is not an open design, we tried our best to make C645 lenses

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work like native GF lenses. The earlier firmware versions required an avatar lens to make the
camera body accept the adapter. That led to many problems. A GF63 was needed to activate the
adapter. Aperture was not displayed and recorded correctly. And all Contax lenses were
recognized as GF63/2.8. Now, with the latest firmware, all the above issues do not exist anymore.
You don’t need to find a GF63 and activate the adapter. Lens model, aperture and focal length are
all displayed and recorded correctly (except the focal length of 45-90. See the next sector for
details.)
3. Aperture control and Exif recording
There is a built-in aperture ring on Contax 645 lenses similar to GF lenses. However, there is
no ‘A’and ‘C’on that ring. We use the smallest stop on C645 lens’ aperture ring to simulate the C
stop of GF lenses. For example, for C645 140/2.8 lens there are F2.8, F4.0, …, F32, i.e. totally 8
stops, on its aperture ring. When you turn that ring to F32, the aperture is controlled by the
command dial of the camera body. When you turn the ring to other stops, the position of the ring
decides the aperture directly.
In contrast to the previous versions of firmware, now the aperture and focal length
information are all displayed and recorded correctly. See the following table for details.
Contax 645 lenses
Max aperture
Correct aperture
on LCD/EVF and
in EXIF
Recorded focal
length
Correct focal
length in EXIF
Distagon T* 3,5/35
F3.5
Y
35mm
Y
Distagon T* 2,8/45
F2.8
Y
45mm
Y
Distagon T* 3,5/55
F3.5
Y
55mm
Y
Planar T* 2/80
F2.0
Y
80mm
Y
Apo-Makro-Planar T* 4/120
F4.0
Y
120mm
Y
Sonnar T* 2,8/140
F2.8
Y
140mm
Y
2,8/140 + Mutar1.4x
F4.0
Y
196mm
Y
Sonnar T* 4/210
F4.0
Y
210mm
Y
4/210 + Mutar1.4x
F5.6
Y
294mm
Y
Tele-Apotessar T* 4/350
F4.0
Y
63mm
Y
4/350 + Mutar1.4x
F5.6
Y
490mm
Y
Vario-Sonnar T* 4,5/45-90
F4.5
Y
45mm
N(1)
(1): So far the real focal length of zoom lens 45-90 is not recorded correctly. It always be
45mm. This issue may be solved in the future version of the firmware.
4. AF/MF selection and aperture priority
There are two working modes, i.e. AF and MF.
4.1 Lenses with AF support
To enter AF mode, turn aperture ring to any position other than the smallest stop while
camera is off or in playback mode. Then, power on the camera or turn back to the shooting mode.
Meanwhile, make sure the AF/MF switch on the camera is at AF-S position. To enter MF mode,
just turn the aperture ring to the smallest stop and make sure the AF/MF switch on the camera is

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at MF position. If the aperture ring is not set to the smallest stop, AF/MF switch turned to MF will
work for some cases. However, the AF motor may still be instructed to do small movements by
the camera body. That may disturb the MF process and make the experience worse. Turning the
aperture ring to the smallest stop tells the adapter to ignore any AF movement instruction. Thus,
we suggest using command dial of the camera body to control aperture while MF is required.
Be noted that, if you switch to AF while the camera is on and under the shooting mode, or
you have adjusted focus ring’s position manually under AF mode, AF malfunction may occur. If
that happens, just play back your last captured photo and switch back to the shooting mode again.
The adapter and the lens will be reset and the problem will be solved.
4.2 Lenses without AF support
For lenses which do not support AF, yet, just put the AF/MF switch of the camera to MF
position. There is no limitation on the aperture ring’s position.
If you put AF/MF switch to AF positions, the camera may not work properly.
4.3 About aperture priority mode
In field tests, we find that when GFX50s is using adapted lens and set to aperture priority
mode (shutter speed dial on ‘A’), during view finding, the aperture blades may move frequently
with a lot of noise and lead to flashing of LCD or EVF. It only occurs when both AF and aperture
priority are enabled. To help you better understand it, let’s look at GFX50s’ aperture control
strategy.
1) Under MF mode (AM/MF switch on MF), the aperture blades are always wide open during
view finding, metering and focusing until the shutter release button is pressed.
2) Under AF mode with aperture priority disabled (shutter speed dial on positions other than
‘A’), aperture blades move at once when you change aperture setting. During AF process, the
aperture blades may temporarily open to a certain position for focusing.
3) Under AF mode with aperture priority enabled, the camera body controls aperture blades’
position in real time according to the brightness of environment lights during view finding.
Due to the slow response speed of Contax lens’ aperture motor, situation of 3) may bring you
a bad user experience. However, if you are willing to accept that experience, the function will be
OK.
According to the feedbacks of some user who were
using the adapter in studio shooting, the same issue may
occur even shutter speed is set manually under AF mode.
When using studio flashlight, the user set the exposure
preview to off to avoid the very dark viewfinder. Under
that condition, the issue may occur. If you don’t want that,
please use MF instead.
Be noted that all of above logics are decided by the
camera and have nothing to do with the adapter.
5. About auto focus
GFX50s can only do CDAF (contrast detection AF). However, Contax 645 lenses are solely
designed for PDAF (phase detection AF) cameras. They lack some key features when working on
CDAF bodies. Thus, before future G mount cameras introduce PDAF, it is extremely difficult (if not
impossible) to make Contax 645 lenses AF on G mount and get acceptable performance.

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Thus, so far AF is an experimental feature. Not all Contax 645 lenses support AF (See the
table in part 1. Note: The list of lenses supporting AF may expand after future firmware
upgrades). The speed and accuracy of AF may not satisfy you. If you can’t accept it, please use MF
instead.
Currently only AF-S is supported. If you set the camera to AF-C mode, the lens may keep
hunting and fail to focus.
If possible, half press the shutter release button and let the lens focus for several times may
help improving AF accuracy. And remember, at any time when you feel AF is not working properly,
you may reset the adapter and the lens by playing back a photo and then setting the camera back
to the shooting mode again.
6. Firmware upgrading
Please follow these steps to upgrade your adapter.
1) Download firmware file from Fringer’s website (see README.EN.pdf on adapter’s root
directory for the URL). For example, C6GF_200.BIN means Contax645-GFX adapter V2.00.
2) Get the adapter off the camera. Do not connect G.CAP (if provided), either. Make sure not to
connect the adapter with the computer while it is installed on a camera body.
3) Plug the Micro USB cable to the port inside the tripod mount of the adapter. Be careful! Mind
the direction and do not push too hard. Or you may damage the Micro USB port of the
adapter!
4) Connect the other end of the cable to a USB port of your PC or MAC. Then a mobile drive
named ‘FRINGER’ emerges. Open ‘VERSION.TXT’ on that drive and check current firmware
version (the line begins with ‘Version:’).
5) If upgrading is needed, copy the downloaded firmware file to the drive named ‘FRINGER’.
Then eject the drive. Ejection is a mandatory step for Macs and an optional step for PCs.
Ignore any error messages about the drive. Wait for more than 10 seconds. Then disconnect
the adapter with the computer.
6) Reconnect your adapter with the computer. Check VERSION.TXT again and make sure its
firmware version has changed to the new one.
Note: Do not copy files other than firmware provided by Fringer’s official website to the
adapter.