Autofocus Problems

**MikeNArk** · 07-30-2021, 06:47 PM

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You have probably already checked everything out, but my Sigma 135-400 had similar problems one time. It turned out to be a slightly loose mount plate on the lens. It moved enough to cause intermittent connection problems. Hope you are able to solve these problems soon.

**photogem** · 07-31-2021, 01:23 AM

Originally posted by pentaxian78

Standard Pentax ones for both. I will double check but believe the OS on the lens is turned off.

OK: Its the OS version. The OS sucks battery power even if switched off! A known side effect.

So it could be the batteries. I would buy a cheap no name just to check.

If it turns out to be the battery, then get originals again.

After 10000 shots and such a lens the batteries can be low but the status might still show o.k.

Often it turned out with problems like yours it was just the batteries.

One just has to search.
There is another simple solution: The external Powersupply.
https://www.ebay.com/itm/272008761566?hash=item3f54fc50de:g:okoAAOSwFnFWFPvf

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07-30-2021, 06:47 PM	#16
MikeNArk Loyal Site Supporter Join Date: Sep 2019 Location: Conway, Arkansas Posts: 15,124	Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here. You have probably already checked everything out, but my Sigma 135-400 had similar problems one time. It turned out to be a slightly loose mount plate on the lens. It moved enough to cause intermittent connection problems. Hope you are able to solve these problems soon.

07-31-2021, 01:23 AM	#17
photogem Site Supporter Join Date: Apr 2015 Posts: 3,520	Originally posted by pentaxian78 Standard Pentax ones for both. I will double check but believe the OS on the lens is turned off. OK: Its the OS version. The OS sucks battery power even if switched off! A known side effect. So it could be the batteries. I would buy a cheap no name just to check. If it turns out to be the battery, then get originals again. After 10000 shots and such a lens the batteries can be low but the status might still show o.k. Often it turned out with problems like yours it was just the batteries. One just has to search. There is another simple solution: The external Powersupply. https://www.ebay.com/itm/272008761566?hash=item3f54fc50de:g:okoAAOSwFnFWFPvf