EOS 60D AEB stops working with certain lens at certain settings with Tamron B016 (16-300 macro)

[bbi-man]

On my 60D, I routinely shoot Manual, f36/2.5sec, ISO 400, and with AEB set to +/-1/3. The lens is set at 300mm. My usual lens is an older Tamron A20 (28-300 macro), and with this lens there is no problem at these settings. When I tried a newer Tamron B016 (16-300 macro) at all the same settings, it would not shoot AEB (it shoots the target exposure, only). With the Tamron B016 on the 60D, normal AEB is non-functional everwhere from f22 to f40, but functional from f6.3 through f20.

Also, if I shoot the same bracket by manual setting each exposure, it shoots them all correctly.

I also have a 70D and a Rebel XSi, and when I use the same Tamron B016 that's a problem on the 60D, AEB works normally at the very settings that are causing a problem on the 60D.

How can the f-stop setting of the lens disable AEB with the camera set in manual mode? 

[TTMartin]

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@bbi-man wrote:

On my 60D, I routinely shoot Manual, f36/2.5sec, ISO 400, and with AEB set to +/-1/3. The lens is set at 300mm. My usual lens is an older Tamron A20 (28-300 macro), and with this lens there is no problem at these settings. When I tried a newer Tamron B016 (16-300 macro) at all the same settings, it would not shoot AEB (it shoots the target exposure, only). With the Tamron B016 on the 60D, normal AEB is non-functional everwhere from f22 to f40, but functional from f6.3 through f20.

Also, if I shoot the same bracket by manual setting each exposure, it shoots them all correctly.

I also have a 70D and a Rebel XSi, and when I use the same Tamron B016 that's a problem on the 60D, AEB works normally at the very settings that are causing a problem on the 60D.

How can the f-stop setting of the lens disable AEB with the camera set in manual mode? 

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According to the Tamron website the minimum aperture of the B016 lens varies between f/22 and f/40 depending on the focal length.

If you are using a focal length where the minimum aperture is higher than f/22 I would suspect that it is a miscommunication between your 3rd party lens and the camera.  

[TTMartin]

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@TTMartin wrote:

According to the Tamron website the minimum aperture of the B016 lens varies between f/22 and f/40 depending on the focal length.

If you are using a focal length where the minimum aperture is higher than f/22 I would suspect that it is a miscommunication between your 3rd party lens and the camera.  

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There is nothing that Canon can or will do to change a camera's behavior with a 3rd party lens.

You can and should report the issue to Tamron, and they may issue an update for the lens.

[bbi-man]

Thanks, but it's not a problem with the minimum aperture for the focal length being used. The focal length at which I'm having the problem is at 300mm, and at that focal length the minimum aperture spec is f40. Furthermore, AEB only starts working at f20 or greater, so f22 is also part of the problem zone. Additionally, the lens works fine on my 70D and my Rebel XSi with all settings identical. Also, as I said, I can take all of the exposures that would result from the AEB setting, as long as I set each exposure individually, instead of by means of using AEB.

Never the less, I am simultaneously trying Tamron for an answer, because the problem doesn't happen with other Tamron lenses with comparable focal length and minimum aperture specs when I use those lenses on the 60D.