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I rented a Tamron 150-600 for birding to use on my Canon M6 Mk II. It works well but the first shot when I pick it up takes forever to focus. I carry it over my shoulder turned on which means it is pointing down at nearby ground when I am not shooting. I have it set on the 10m-infinity setting and using 1 point AF and one shot AF. It seems it is so far out of focus there is no contrast at all, then it takes a long time to recover from that. Once the first focus is achieved it is quick for the next shot. I will try turning the camera off and see if that helps.

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  • \$\begingroup\$ Pre-focusing on some far-away object (tree, cloud if border is sharp enough) also helps. \$\endgroup\$
    – xenoid
    Nov 3, 2021 at 18:08
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    \$\begingroup\$ I think I have the same glass (TAMRON SP 150-600mm F/5-6.3 Di VC USD G2 A022 ?) and haven't experienced any issues with it with Canon EOS 2000D. Are you perhaps using EF-M + some converting mount? Also, try to set VC 2 or VC 3. If you have another camera, try comparing, I'd bet it's the converter's or camera's fault, especially judging by the notice from Tamron about firmware update. \$\endgroup\$ Nov 3, 2021 at 19:16
  • \$\begingroup\$ @PeterBadida: yes, I am using the Canon EF-M converting mount. The lens seems to drift toward the near focus when not being used, whether the camera is on or not. It helps to point it at something 5 meters away or so, then swing up to a farther view. I suspect my copy is new enough to have the firmware update, but I don't know how to check. I don't have another camera to check it on. \$\endgroup\$ Nov 4, 2021 at 2:38
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    \$\begingroup\$ I use a Canon EOS M5 and had the same issue with the Sigma 150-600mm. However I was reassured that the issue was happening due to the converter although I was using the Canon Adaptor! Something to do with power and connectivity. In the end, I returned the Sigma. I sometimes get the same issue if I use the Canon 70-300mm L f/5.6! I find that the only lenses that run Hassle free are the EF-M lenses. \$\endgroup\$ Nov 5, 2021 at 16:17
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    \$\begingroup\$ @PeterBadida: I looked up the firmware update, which claims to provide compatibility with the R series mirrorless but does not say anything about M series (with the APS-C sensor). Thanks \$\endgroup\$ Nov 5, 2021 at 21:06

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Try carrying the lens over your shoulder with the front pointed sideways towards your other shoulder, rather than down. Gravity will pull the focus elements down when you're walking and the lens is pointed down and no power is supplied to the AF motor. It's much like zoom creep.

To feel just how much gravity affects the heavy zoom and focus elements in lenses of this size, try this when you're sitting at home. Point the front of the lens straight up and twist the focus ring or zoom ring in both directions. You'll likely notice greater resistance in one direction than the other for each. Then flip the lens so it is pointing down and repeat the test. You'll likely notice the increased resistance is now when you twist each ring in the opposite direction than before. It's gravity that is the difference!

I really noticed this with a (well used) Sigma 120-300mm f/2.8 Sports I recently used. I had the lens attached to a monopod via the tripod collar. Once I put the monopod over my left shoulder with the lens pointed towards my right shoulder the focus did not creep.

When I first tested the 120-300mm f/2.8 lens I thought it was defective because the focus ring was so much harder to turn in one direction than the other. I was testing it with the lens pointed straight down. Then I thought to point the lens straight up and, lo and behold, it was then equally harder to twist the same ring in the opposite direction. This is even a lens with no extension due to zooming or focusing. It's all internal.

An advantage of putting the monopod over the left shoulder is that the torque acting on the attachment between the monopod and tripod collar will be in the tightening direction, rather than in the loosening direction if you put the monopod over your right shoulder with the lens pointed towards your left shoulder.

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  • \$\begingroup\$ I have used the Canon 100-400 Mk 1 with the adapter and with and without the 1.4x extender with no problems. Maybe its focus element is lighter. The Tamron had two tripod sockets on the lens, so I switched the sling to one that pointed the lens up. It didn't change the direction the focus moved. \$\endgroup\$ Nov 5, 2021 at 21:02

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