I've put a dandelion chip (4th gen) on my Samyang 500mm f/6.3. I shoot a Canon 6D by the way. So, that's cool now I've set the chip to return f/6.3 and I can get a correctly exposed LiveView, EXIF shows 500mm, that's nice. But the main thing I was looking for, the AF-confirm, is still not working.

As anyone tried this chip on this specific lens and successfully set the back/front focus correction?


2 Answers 2


If you programmed the chip to return the correct maximum aperture of f/6.3, Autofocus on an EOS 6D is disabled, and therefore also AF-Confirm does not work. The AF-Sensors on this camera need at least a maximum Aperture of f/5.6 to work.

You can look at this question and it's answer for more detailed information.

  • To compensate (if you think AF will actually work reliably with f/6.3 in a bright situation), you could set a fake aperture of f/5.6 and then use exposure compensation to adjust to the right exposure. Then the camera would meter 'correctly' and on a bright situation you may get AF confirmation as well.
    – rfusca
    Mar 13, 2014 at 1:09
  • Guys, sorry for the long time of reply. I only saw your comments at the moment. Anyway thanks for your inputs, I'll try this ASAP and tell you what :). Cheers!
    – user186258
    May 23, 2014 at 12:17

Interestingly on Contax AX (an analogue camera) which has exclusive AF-function for C/Y-lenses, there is also f5.6 AF-limit, but (I proved it and had been confirmed about it) if using a catadioptic mirror lens beyond f.5.6 maybe f8 limited. AF is possible even in dim light like I had in the evening in the shop. Vivitar CAT 600/8.(nb: not that sharp but sharp enough above all with APS-C- have also a noname 300/5.6 which is in FC-testing. Many surprises using all kind of EOS-adapters. Also NI-EOS (all of them in MF-mode don't beep. Manuals tell which modes don't beep. Please concentrate on the signal first: green dot and focus-point(s) blinking). Most important finding lately: I am slowly reentering FC-adventures. I had the beep, but all of a sudden it was gone: also no confirmation. Setting to selective helped. There must be another function which is switching this function.

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