Canon: will an adapter with an EMF AF Confirm chip work with my vintage lens?

Yes. The EMF chip, when properly positioned and glued to an adapter ring, will perform auto focus confirmation and communicate EXIF ​​lens information (focal length, maximum aperture, and even the aperture setting used)Yes follow the right steps while shooting) on ​​a Canon EOS digital body (I've used them on an XT, 50D, and 5DMkII). The adapter ring and the lens to which it is connected do not really affect this function. The quality / fit of the adapter ring, however, is independent of the chip. The chip is sold separately from the rings, and can be pasted by anyone.

You can also refer to the EMF chip manual.

However, in my experience, AF confirmation is not as useful for pinning focus with a very thin DoF on a fast lens like Canon's "matte precision" focusing displays (if your camera body allows use one), or live view at 10x magnification or maximum focus and Magic Zoom to the Magic Lantern.

sensors – How do Android EMF detectors work?

The question does not only apply to Android phones, but to all mobile devices. Our mobile devices use EMF to communicate. Mobile phones are, by definition, devices that can detect EMF from their ability to communicate depends on radiofrequency fluctuations in electromagnetic fields. Our devices, especially smartphones, which rely heavily on Internet services, emit a large amount of EMF radiation. That should imply that mobile phones can detect and manipulate EMF accurately, right? No. Our phones are designed to works only with specific frequencies, approximately 800 to 2.2GHz, so it is quite unlikely that a mobile phone can detect general fluctuations in EMF.
Now, the creator of the application could tell him that he uses a magnetic sensor, and he might think that EMF can be detected using a magnetic sensor, since it is also (in part) a magnetic wave, but he can't. EMF exists when a wave has both electrical and magnetic parts.