these will cause an error if directly connected to a Panasonic camera - use basic adapters instead.
the most common chip used is a Dandelion programmable chip which you can buy separately and glue to a basic adapter.
search Ebay for cheaper Chinese versions
manual aperture-control lens adapters
mainly for use with lenses without aperture rings - eg. Nikon G, Minolta AF, Pentax K, Canon EOS
if you use an adapter without aperture control on these lenses, the aperture will be fixed wide open unless you stopped it down on a dSLR of the same brand by holding down the DOF preview button as you removed the lens - the aprture will then be fixed at the aperture set prior to removal of the lens.
relatively fast PDAF support for E-M1 with certain lenses BUT NOT Canon EF 135mm f/2.0L lens which will not AF with the E-M1 but will do via CDAF on other cameras
this quirk arises as the E-M1 defaults to PDAF mode only (and no CDAF) is the attached lens is not recognised as having CDAF compatibility - unfortunately user cannot force the E-M1 to use CDAF mode
relatively fast CDAF on cameras excluding E-M1, including face detect AF
multi-pt area AF, C-AF and AF tracking modes do NOT work well
OIS works if lens OIS is ON but no dual IS support at this stage
see also the Metabones Speed Booster 0.71x focal reducer adapter!!
Viltrox AF EF-M1 adapter
announced may 2017, Canon EF to MFT
Sony have a basic adapter for Sony alpha lenses for NEX cameras with aperture control but no AF
Sony have a large, expensive phase contrast AF adapter for Sony alpha lense on NEX cameras
0.71x focal length reducer = adds 1 f-stop more light and allows almost full frame field of view on APS-C cameras (become 1.09x crop factor) while MicroFourThirds cameras will have an effective 1.42x crop factor
the EOS adapter will also allow aperture control, OIS, EXIF, fast PDAF (on E-M1) and very slow CDAF (for post-2006 EF lenses)
these adapters allow a filter to be “dropped in” to the adapter thereby allowing the same filter to be used irrespective of which lens is being used
this is very handy when using lens with very large filter threads or no filter threads such as ultra-wide angle lenses or fisheye lenses
if only they would make one for Four Thirds to Micro Four Thirds - be very handy for use with the Olympus ZD 7-14mm f/4 lens with a ND400 filter for long exposure bright sun shots of blurred water
having a filter in place also allows changing lenses without risk of dust entering the camera body and landing on the sensor
eg. Canon EOS or Nikon F to Micro Four Thirds or Sony NEX
variable neutral density filter adapters
these are adapters which allow a variable neutral density filter within the adapter to change the light transmission without affecting aperture which is highly desirable in videography in particular
variable neutral density filters tend to give weird artefacts on wide angle lenses