R7 Autofocus Hunting Issue with Tamron 18-400mm Lens

[sonoma]

I've been having consistent autofocus issues trying to use my R7 with the Tamron 18-400mm lens using the control ring EF-EOS to R mount adapter.  The lens will often work fine for the first 5-10 minutes of a photo shoot, but then it will start hunting for focus and be unable to focus on anything.  Turning the power off and back on doesn't help.  The firmware on both the camera and lens have been updated to the latest versions.  I shipped the lens to Tamron for troubleshooting and repair, and they adjusted the autofocus, but that hasn't resolved the problem.  The lens works fine on my older Rebel T4i that has the same EF-S mount as the Tamron lens so no adapter is needed.  Is it possible that the mount adapter is defective?  Or does the R7 with the mount adapter just not work properly with the Tamron lens?  According to Tamron, the R7 is supported with this lens.

[cranfordrd]

I think that makes sense, I may just buy the RF 100-400 if switching out the adapter doesn't help. I used the Tamron for 4 years so it's not a total loss.

[cranfordrd · Accepted solution]

Just wanted to update everyone. I exchanged the adapter that had the extra ring on it for a plain one AND walked into the Tamron USA headquarters (lucky me, it happens to be 10 mins away, who knew!?), they updated the firmware on the lens. Played around for about 30 mins and so far its great, no AF hunting!

[ctitanic]

Wonderful news. Thanks for letting us know.

[March411]

Perfect, and now that lens that you've had for the last four years......is still going to be serving you well!

Firmware update resolved the challenge, glad it worked out. Now we know the Tamron 18-400mm Lens can/will work on the R7

If you don't mind mark a post as resolved so that when people search they can easily find the fix.