Recently bought a PK-EOS ring adaptor for my older Pentax K lenses. I went with one that has an AF confirm chip. But, this chip causes "Communications error" and locks all camera functions.

I've discovered that some of these types of chips are programmable (they're called "Dandelion chips", apparently), but some aren't? I have found a couple of different methods for attempting to program it, but the camera locks up so I can't follow any steps of the guide.

I noticed that the product listing doesn't include 650D, but rather specifies 600D. Wondering what the differences are, and if there's any solution to my problem? It wasn't expensive, but it would be a bit frustrating if it doesn't work!

  • I use chipless adapters, so don't have any experience with AF-confirm chips. Canon is known to have tweaked the EF protocol over the years. Based on your description, seems the omission of the 650D from the supported camera list wasn't accidental.
    – xiota
    Mar 5, 2019 at 5:13
  • Have you checked that the contacts of the xhip are properly aligned? Also, maybe it is just the chip that is broken. But of course xiota could be right, too.
    – flolilo
    Mar 5, 2019 at 10:42

1 Answer 1


It sounds like your adapter was developed earlier than the EOS Rebel T4i/650D. The third party makers of such adapters don't license technology from Canon, they reverse engineer it. If Canon starts using a part of their existing protocol that hasn't been used in the past, reverse engineered third party products sometimes don't work with the new devices. This happens with third party batteries, lenses, teleconverters, flashes, etc.

Some lens makers will issue firmware updates to make their slightly older lenses work with newer camera bodies. Sometimes that requires a trip to a service center to reprogram or change a chip. Recently both Sigma and Tamron have created USB docks that attach directly to the lens that allows the end user to update firmware (and do other helpful things as well). This allows them to bypass trying to update a lens using the interface on the incompatible camera.

Many third party battery makers will replace batteries that were already in dealers inventories with newer versions that have updated firmware reverse engineered after the release of a new camera body if the buyer contacts them and explains that the battery was purchased to be used in a recently released model that has an update making the older version of the third party battery incompatible.

For lens adapters, though, I've never heard of makers/sellers sending a buyer a newer update if the adapter they bought doesn't work with a newer camera. It couldn't hurt to contact them and ask. Considering that the EOS Rebel T4i/650D has been out for quite a while, I wouldn't expect much luck on that front. They're just as likely to say something like, "You should have read the description before you ordered it."

If the chip is programmable and can be updated to work with the EOS Rebel T4i/650D, you're going to have to connect to it using an interface other than your camera.

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