Four Thirds to Micro FT adapters

Soon after the Micro FourThirds system was launched in 2008, adapters became available to connect Four Thirds lenses to the Micro Four Thirds mount, which is narrower and designed for lenses with a shorter flange focal distance than FT. These adapters make it possible for the photographer to use the whole range of Four Thirds lenses with a Micro Four Thirds body. Two types of adapters are available: purely mechanical tubes and devices with electrical signal passthrough. The purely mechanical adapters are cheap, but of limited use, as they do not transmit any information between the FT lens and the MFT body to control, for example, the aperture and focus motor of the lens. The following discussion deals only with adapters that maintain autofocus capability and aperture control.

These autofocus adapters are passive feedthrough devices without any logic circuitry of their own. They convert the 9-contact Four Thirds SLR electrical connection to the Micro-our Thirds 11-contacts. They make it possible to meter, autofocus, record exif data, and inform the image stabilization system.

Not every FT lens will autofocus equally well on every MFT camera body. These performance differences are, however, not in any way related to the adapter, but the autofocus systems of the camera and lens. The Olympus OMD-EM1 has a phase detect autofocus system (in addition to one based a contrast detection) and autofocuses all FT lenses as quickly and precisely as a native FourThirds camera. In contrast, MFT cameras with only contrast-detect autofocus systems (CDAF) will generally focus FT lenses more slowly (but with equal accuracy). The exception to the slow focusing performance on CDAF cameras are more recent FT lenses that feature an Imager-AF and will autofocus in a manner similar to a native MFT lens. The following six FT lenses from Olympus feature Imager-AF: 2.8/25mm, 4-5.6/9-18mm, 3.5-5.6/14-42mm, 2.8-3.5/14-54mm II, 4-5.6/40-150mm, and 4-5.6/70-300mm. On mFT cameras from Panasonic, selected FT lenses will not autofocus at all and can only be operated in manual focusing mode. Usefully, Panasonic has made compatibility tables available that make it possible to determine which camera and lens combinations are concerned. No corresponding list of camera-lens compatibility exists from Olympus, but some Sigma FT-lenses, including their 2.8/105mm Macro and 2.8/150mm Macro, have been reported to only function in MF mode when attached to a CDAF camera from Olympus.

There are several different FourThirds adapters available from original equipment manufacturers and third party suppliers. They all perform the basic functions of attaching the FT lens securely and transmitting data between the lens and the camera body equally well. All adapters have a width of 19.5mm and a diameter of about 65mm, and are supplied with front and rear caps. Also, all FT adapters seem to be manufactured in East Asia. Yet, there are differences with respect to other features, such as color, body-material, weathersealing, tripod-attachment, weight, and - last but not least - price. The adjacent table provides an overview of the differences.

Specifications of FT adapters
M43 AF1
MTM 100
Color Black Black/Silver Black Silver Black Black Gray Black/Silver
Body material Metal Plastic Plastic Metal Plastic Plastic Metal Metal
Dust- and splashproof No No No No No Yes No No
Tripod mount Yes Yes No No No No No No
Weight (g) 168 88 85 83 41 42 87 83
Price new (USD) 70 45 60 210 170 180 100 50
Check current offers ebay

FT adapters come in different colors to match the camera and/or lens used. The original adapter from Olympus (the MMF-1), for example, was silver-colored, while the subsequent MMF-2 and MMF-3 are black. Some third party suppliers offer their adapters in both silver and black, so that the customer has the free choice. Another difference is the material that the adapters are made from. Plastic adapters often weigh only half as much as those made out of metal, while the latter provide a reassuring heft (although there have been no reports to date of plastic adapters breaking).

The Olympus MMF-3 is currently the only dust- and splashproof FT adapter, and, hence, well suited for use with those MFT cameras and the twelve High Grade and Super High Grade FT lenses that are weathersealed. Moreover, some third party suppliers offer models with tripod mounts integrated into the adapter. This feature will be particularly useful to relieve strain on the camera base when shooting on a tripod with lenses that are quite heavy, but do not have a tripod collar (such as the 4/7-14mm or the 4-5.6/70-300mm). In this context, the Novoflex ASTAT-MFT lens collar for Micro Four Thirds Adapters (here at Amazon) might also be of interest as a support option. It clamps around the FT adapter and takes the weight of the lens and adapter off the camera when mounted on a tripod. The Novoflex collar comes with a mounting plate that is compatible with Arca-Swiss style quick release mechanisms.

FT adapter FAQ

Can the Panasonic adapter be used with an Olympus camera?

Yes, the 43 adapters are functionally interchangeable. A Panasonic adapter will work with Olympus cameras and lenses, and an Olympus adapter will function properly with Panasonic equipment.

What is the difference between the Olympus MMF-2 and MMF-3 adapters?

The MMF-3 features an O-ring on the camera side that makes it dust- and splashproof.

Does the adapter change the maximum aperture or focal length of the lens?

No, the specifications of the lens remain unchanged. The adapter just compensates for the different size of the mFT and FT lens mounts and the differing flange-focal distance.

Can the 4/3 adapter be used in combination with a tele-converter or extension tube?

Yes, the EC-14, EC-20, and EX-25 will work properly when mounted on an MFT camera through an FT adapter. However, Olympus does not recommend these combinations.

Will the in-body image stabilization system (IBIS) work with the FT adapter?

Yes, the image stabilization will work just as well as with native m43 lenses.

What is meant by "active autofocus" in some of the adapter descriptions on ebay?

The vendor tries to differentiate the offer from simple adapter-tubes that do not contain the electrical contacts to pass information between the lens and the camera. The word "active" is somewhat misleading, as the adapters are just passively passing through data.

Does the use of a FT adapter degrade image quality?

A 43 adapter does not contain any optical elements, but could still have an adverse impact on image quality if the adapter were mis-aligned, would let in stray light, or reflect light internally to create flare. In general, the listed concerns are not pertinent. However, there are some reports that early versions of the Viltrox adapter were not perfectly aligned and led to poor corner sharpness on wide-angle lenses, such as the Olympus 7-14mm f/4. It is unclear, though, whether this problem persists or whether it was merely related to a bad batch or poor copy of the adapter.

Do all the Olympus lenses that potentially support "Imager AF" perform well on mFT cameras?

Some of the lenses that potentially support "Imager AF" require a firmware update to activate the feature, so that it is advisable to ensure that the latest firmware version is loaded.

Further Reading

Micro Four Thirds continues to develop and new cameras and lenses are regularly added to the system. Usefully, both Olympus and Panasonic provide information on upcoming lens releases to guide photographers in their equipment choices. You can check what is in the pipeline on the Olympus lens roadmap and the Panasonic mFT roadmap. Also, in case you are interested to find out how a particular FT or MFT lens will look on your camera, you can use the the simulation tool at to see the combination from different perspectives.