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02-26-2013, 04:02 PM   #1
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18-55 wr frontal lens holder issue

Hi to everyone,

from the first day i handled my 18-55 wr kit lens i was'n so really sadisfied... i was sure the lens has some focus issue like front or back focus.

I tried for days to tune it via the af fine setup (using the focus chart and after i have read every kind of tutorials) but every test i made was different from the previous.

The focus is not accurate and i suppose the reason is that the frontal part is not really solid but touching it it can go in and out and the focus change! Impossible to fine
tune the autofocus if the movement of the frontal lens is bigger than correction....
To show you this i attach a little video, i was wery gentle moving it, no strong
https://www.youtube.com/watch?v=5-D7ZtYpbYs


So i'd like to know if someone can check the own 18-55 wr and tell me if it present the same issue.
And someone know if i can fix the lens in some way?

Really thanks to everyone and excuse me for my english.

02-26-2013, 06:14 PM   #2
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Mine is like that too.

But the images I get from it are just fine.

Never had a Focus issue.



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02-26-2013, 06:26 PM   #3
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I do own the same lens, and there is some movement, too. But approximatly 20% of what I see in your video.

Also, the Pentax AF system is a kind of closed loop - different from some of the competitions's. This makes it slower, but should (in theory) compensate for hysteresis effects. Of course only if the movement is restricted to the complete lens block used for distance setting.

EDIT:
What's about sharpness if you use manual focusing? There you are doing the "closed loop" with your eyes and fingers.
03-01-2013, 09:31 AM   #4
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QuoteOriginally posted by Corto-PA Quote
Mine is like that too.
But the images I get from it are just fine.
Never had a Focus issue.
Thank you for your support!
And very nice photo.

I'll try to do others tests hoping to have that IQ. May i ask you the time shutter and the f number you used in your photo? Thank you.

03-01-2013, 09:43 AM   #5
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QuoteOriginally posted by RKKS08 Quote
I do own the same lens, and there is some movement, too. But approximatly 20% of what I see in your video.

Also, the Pentax AF system is a kind of closed loop - different from some of the competitions's. This makes it slower, but should (in theory) compensate for hysteresis effects. Of course only if the movement is restricted to the complete lens block used for distance setting.

EDIT:
What's about sharpness if you use manual focusing? There you are doing the "closed loop" with your eyes and fingers.
Thank you for your support,
i have tested that AF system can focus correctly also i have the front lens holder gently pushed in or pulled out, the AF system can recognize the correct focus also in this situation.

So it's possible that the auto focus (in AF-S mode) fails if some movement of the frontal lens horder occurs in the time between the half press button and the shot, maybe the AF-C could help me in this case.

For the sharpness in manual focus (and in autofocus), if you can help me, i'd like to show you some photos hoping you can say me if it's ok.

Thank you.
03-01-2013, 04:42 PM   #6
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QuoteOriginally posted by johnnick Quote
Thank you for your support!
And very nice photo.

I'll try to do others tests hoping to have that IQ. May i ask you the time shutter and the f number you used in your photo? Thank you.
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03-01-2013, 08:04 PM   #7
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I just tested my 18-55mm WR and there is only very slight movement compared to that in your video. I have never had a focus problem with the lens on my K10D.

I am not sure if yours is within the production tolerance. Maybe you have a bad copy.
03-02-2013, 04:43 PM   #8
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I've got about the same amount of movement on my 18-55 WR. It's always been like that and is makes no difference to AF or AF setup. Why should it ?



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