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SAL16-50 AF issues on a77II

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Tjeiken View Drop Down
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Post Options Post Options   Quote Tjeiken Quote  Post ReplyReply Direct Link To This Post Topic: SAL16-50 AF issues on a77II
    Posted: 27 December 2023 at 10:27
During a recent trip, I suddenly discovered that a lot of my photos were out of focus - something i have never had issues with before (i have shot with this setup for 5+ years).

Today, I tried to fault-find a bit more, and do some test shots to figure if there is actually an issue.

What I find is, that the AF is quite consistently back-focusing by almost 5 cm when at wide angles (~16-24mm).. AF-A or AF-S doesnt make any difference. Center point focus.
When between 24-50mm, the AF seems to be quite accurate.

What can explain this issue suddenly turning up?
I turned to shooting with other lenses instead, but I don't have any other wide angle AF lenses in my setup, to cross check if it is a lens or a camera issue.
I mainly resolved to shooting with a 35mm prime instead. No issues seen on this one.

Anyone experienced something similar?
Does it make sense to send it for repair at Sony? (I guess, quite expensive)

Edited by Tjeiken - 27 December 2023 at 10:30
Sony a77II | SAL1650F2.8 | SAL16105 | SAL35F18 | Minolta 50F1.7 | Minolta 70-210 F4 (BC) | Samyang 8mm | Sigma wide CPL | Metz 58 AF-2 | Curiosity and ingenuity
 



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neilt3 View Drop Down
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 27 December 2023 at 16:55
I don't have a problem with mine , though I tend to have the 18-135mm SAM on mine .

Just one thought .
Have you recently cleaned the sensor and not quite clipped the mirror back down properly ?

Although that would effect all lenses , a wider angle lens might more more effected , and smaller apertures of some telephotos might cover the difference a bit .

Don't know , but worth checking first to at least rule that out.
see my photostream on flickr;
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Tjeiken View Drop Down
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Post Options Post Options   Quote Tjeiken Quote  Post ReplyReply Direct Link To This Post Posted: 28 December 2023 at 07:22
Thanks for the suggestion, though i am quite sure that is not the case.. the precision of the AF is going from way off to spot on at just around 24mm.. really weird..! It almost seems like the AF is "catching" something wrong at the longer focal lengths..
Sony a77II | SAL1650F2.8 | SAL16105 | SAL35F18 | Minolta 50F1.7 | Minolta 70-210 F4 (BC) | Samyang 8mm | Sigma wide CPL | Metz 58 AF-2 | Curiosity and ingenuity
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 28 December 2023 at 08:21
Another possibility, that would also be an easy fix , is dust on the AF sensor.
On the SLT cameras the AF sensor is on the top of the mirror box , in front of it .
So in the open area where dust and fluff could easily accumulate .

I've had this issue with DSLRs where the sensor is behind the mirror at the bottom of the mirror box .

The solution was to use a blower bulb and give it a good blasting , making sure not to touch either the mirror or AF sensor with the tip of the bulb .

Depending on how the dirt had settled on the AF sensor and how the light reached the sensor could alter it's behaviour.
I found that as the light was blocked from reaching parts of the AF sensor, it struggled to lock focus , rather than focus being off .

It's a simple fix to just clean , and won't cost you any money to check either .

At least you can rule that out before sending away .

As it's just the 16-50 misbehaving, can you get access to another wide angle lens to see if that behaves the same ?
see my photostream on flickr;
http://www.flickr.com/photos/neilt3/
C & C welcome.
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addy landzaat View Drop Down
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Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 28 December 2023 at 09:54
According to your signature you have the Sony 16-105? Do you have access to another A-mount capable camera?

With problems between lenses and cameras it is good practice to clean the contacts of lens and camera.

Another option is to remove the battery for a longer time (over an hour).
Do a factory reset.

Replacing the lens probably is cheaper then repair - buy a used one from a European store with warranty at around 250,-:
https://asgoodasnew.de/Foto-Video/Objektive/Sony-SAL1650-16-50mm-f2-8-Objektiv-A-Mount-wie-neu.html
https://www.kameraclub.de/Sony-SAL-16-50mm-F28-DT-SSM-A-Mount-SO20191-B9092
https://www.refoto.nl/default/objectieven/occasions-en-demo/sony-16-50mm-f2-8-dt-smm-a-mount-objectief-occ.html
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Phil Wood View Drop Down
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Post Options Post Options   Quote Phil Wood Quote  Post ReplyReply Direct Link To This Post Posted: 29 December 2023 at 01:56
Can you manually focus accurately at the wide end? Does the focus feel stiffer at that end? Just wondering if it's something mechanical that a good clean would fix.
 



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addy landzaat View Drop Down
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Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 29 December 2023 at 12:12
Just thought about something: do you have priority set to AF or release?
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Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 29 December 2023 at 17:10
I came across a SAL DT 16-50mm f2.8 SSM for just 149,- at Hans Keuzekamp, a brick and mortar camera shop in the city Zwolle: https://www.fotohanskeuzekamp.nl/verzending-via-foto-hans-keuzekamp

I bought from them before several times with no issue and with a personal touch. They ship to EU countries. Site is in Dutch, but Google Translate might be helpful.

Edited by addy landzaat - 29 December 2023 at 19:24
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