Sigma 400mm Lens Goes Haywire.

Thanks, but that advisory doesn't say my Sigma lens - which doesn't have the HyperSonic Motor HSM designation - will be affected. But Dpreview says it may in the side note. Yet no one says anything about the lenses subsequently not working with compatible DSLRs.
Regards,
Renato

Thanks Michel,
         I hadn't known that about the higher torque in the A77 - very interesting.
It does seem a tad too coincidental that the lens started not working straight after using it on the A77.
It might be a good idea not to use my my other more expemsive Sigma lenses on the A77.
But I do have some cheap Sigma zooms, which I might try out.
Regards,
Renato

_Michel_ wrote:

I have read in the past (when the A77 came on the market) that problems could occur due to the powerful torque of this camera. It could broke the tooth of the plastic gear when the focus ring hit a stop (min or max distance).

I don't know if your 400 mm has plastic gear but since it does not work anymore with your 5D if I understood correctly, the worst case is possible unfortunately .

Hoping I'm wrong, Michel.

_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

Hi Michel,
Thanks so much for digging that thread up for me. Curiously, when I clicked on it, I got a "Page Not Found". But when I Googled the title, it came up fine. Then I read it and the other pages, and got a terrible feeling in the pit of my stomach.
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People have had Sigma gear stripping with the A200 and A230!!!! And gear stripping of EX lenses and the Bigma - I own the Bigma and a few EX lenses. Not to mention lenty of other people with stuffed 400mm Sigma lenses like mine.
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It would seem that I had better reserve my Sigma lenses for use in my older and hopefully less powerful cameras. I wonder if any stripping could occur with the LA-EA4 adapter, as I'm getting an A7s soon?
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Thanks again. I think you have saved me a lot of money.
Regards,
Renato

SQLGuy wrote:

You should be able to check whether there's a stripped gear.

If you turn the focus ring with the lens detached from the camera, you should see the screw drive head in the breech turning. If it's not turning when the focus ring is turned, then something is certainly damaged in the AF drive mechanism. If it is turning, you can put a small screwdriver in the slot and put LIGHT resistance on it while turning the focus ring. If you that the screwdriver starts slipping or things feel really gritty, that would probably indicate a broken or stripped tooth.

I didn't see anyone selling this repair part, and Sigma seems to be pretty bad about parts availability for their older lenses... but it would probably be something that could be 3D printed.

Thanks very much for your input.
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I've done as you said, and when I turn the focus ring the screw drive head turns too.
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But the turning of the focus ring isn't smooth at all - it gets lightly stuck three times through the mid to long focus part of the range requiring slightly more pressure to keep it turning. And it gets more stuck once at the closer focus part of the range - requiring considerable pressure to keep turning it at that point. Which I think explains where the problem is coming from, and why the KM5D seems to work with it some of the time. Though why its autofocus won't function at all in the A700 remains unexplained.
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I have 400mm Tokina SD lens attached to the A77 at the moment, so even if the Sigma isn't repairable, I can still always use it as  a manual focus lens in a NEX camera.
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Regards,
Renato

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

neilt3 wrote:

I think I found the slow setting to be fast enough anyway , and more precise .

The fast setting I think sometimes missed focus more often .

So I think all my cameras are set to slow , a700,a900 & a77ii .

I think it was my a100 that killed a Sigma 75-300mm , no great loss !

Thanks, it will be interesting to compare fast and slow focusing in my cameras.
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I also have an A550 which I perceived as being much faster at focusing then those that preceeded it - but it doesn't have a Fast and Slow AF setting. I suspect I had better keep the Sigma lenses away from it.
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I think it is always a time of sadness and regret when any lens dies.
My second hand A7s showed up in the mail today, and I put an LA-EA4 adapter on it, together with a really old and cheap Sigma 28-75  f/3.5 to 5.6 (same as the A7 kit lens).
It will be interesting to see if I will be regretting its passing in the near future.
Cheers,
Renato

neilt3 wrote:

Regards fast and slow AF , it might be better to call it "standard AF Speed " and "faster AF Speed" .

All cameras work as a standard / slow speed .

Only certain cameras have the faster setting .

So the A5** models don't have two options , they don't have the hardware for the faster speed , hence the absence of a "fast " setting .

It's just some lenses are more susceptible and being old lenses have more wear to the gears .

I had the a580 , and although I would call the AF speed satisfactory it certainly wasn't fast .

Again, thanks very much.
That's comforting news with respect to Sigma lens usage on my A550.
Regards,
Renato