Sigma 400mm Lens Goes Haywire.

neilt3 wrote:

_Michel_ wrote:

A link to a thread I just discovered on dyxum lenses where I was looking at gear construction with sigma (not found so far)

https://www.dyxum.com/dforum/recent-cases-of-sigma-gear-stripping-anyone_topic51349_page3

Some people have had this problem with the A700 too

I was looking for my sigma 70-210, APO-Macro but I think (and hope) the A68 has less tork because I think this lens has the plactic gear too unfortunately.

Michel

Check in the cameras menu .

On the cameras that are prone/ capable of stripping the gears they tend to have two settings .

With Minolta lenses either setting can be used , with some third party lenses , it needs to be calmed down a bit .

In the camera settings it says something like "AF Speed" and can be set to "Fast" or "Slow" .

Set the camera to "Slow" .

The reason is ( IIRC) is on the fast setting the AF motor moves fast and can change direction at some speed and force . That's what causes the plastic gears to get stripped .

Cameras with the stronger motors , the a700 etc , had this setting .

Cameras without this setting don't have the more powerful drive , and therefore don't need it .

Some lenses are in better condition than others after maybe 30 years if use and might be more ready to break , in which case , a slower speed AF might not help !

Thanks so much for that information.
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I found that setting on the A77 and changed it to slow.  I had never known it existed. I'll be doing the same on the A700.
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Or I might be putting sticky notes on all my Sigma lenses with "Set Drive speed to low".
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And I'll just have to remember to set the drive speed higher with good Minolta glass.
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Regards,
Renato