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02-06-2011, 11:06 AM   #1
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[langtitle=fr]K5 AF Problem with Tamron 90 mm Macro[/langtitle]

Hello,

I have just tried for the first time my New Pentax K5 with my Tamron 90mm Macro.
the Autofocus is absolutelly not working well...it is simply horrible...
If I am not far from the ideal focus, the camera is able to find the focus (sometime)... If i am far from the ideal focus, the camera is enable to find it...

I have seen people that seems to have the same problem, and some other not...

I have contacted Pentax support and I am waiting for their answer... but no news until now

Did someone found a solution to this problem?
Is it a compatibility problem ?
Is the K5 deffinitivelly unable to make focus with the Tamron 90mm ?
Does someone received an answer from pentax or send it back to the support ?

I will appreciate any help before selling the lense to by an other one that has no problem with the K5

Thanks

LP

02-06-2011, 11:17 AM   #2
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I'm going to assume the translation is somewhat messed up in your post. I don't know what Canon support would have to do with Pentax.

As to your problem, remember at very close (macro) range, your focus is going to have to be very precise and steady. Try switching on Live View and see if that changes your luck. You might also post a couple photos demonstrating your problem along with your shooting conditions.

02-06-2011, 11:55 AM   #3
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My K-5 and Tamron 90/2.8 macro work fine together so I don't think there is a compatibility issue. However for very close macro shots I seldom use AF. As Jeff said, Live View is your friend. I will assume that you fully understand the use of the focus limiter switch on the side of the lens.

Also as Jeff said, please post samples with EXIF for better help here.
02-06-2011, 12:05 PM   #4
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Yes, AF does not do very well in the macro range, so that may be your problem. If you're not in the macro range, use the focus limiter switch on the lens (set it to "limit"), that will also help.

02-07-2011, 12:55 AM   #5
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Original Poster

Of course I have contacted Pentax Support

I have tried any AF different options like spot for instance and I noticed no change

I have tried the option to reduce the range of the lense and nothing is better

the camera juste dont try to find the focus... it does nothing...it seems to be lost ... and is not trying to go through the whole range to find the focus like my K7 did before

If I approch manually the focus, the camera finish the job !

the Line view does better but is not perfect ...

With other lenses I have, I have not notice any problem
02-16-2011, 09:20 AM   #6
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Use manual focus rather than AF

I've just finished taking a macrophotography course at the Chicago Botanic Garden. Our instructor, a pro, kept hammering at us to "use manual focusing, not autofocus," on whatever camera we had. It's not that autofocus on any camera does poorly at macro settings, but that the photographer is better able to choose the precise point of focus by doing it manually. With flower shots, for example, one often wants a certain point, such as a stamen or pistil, to be tack sharp but the rest in softer focus.

So I learned to wield my Tamron 90mm on both my K-5 and K20D manually to achieve that selective focus, and will never go back to autofocus. My photos are simply better.

At greater-than-macro distances, the Tammy autofocus does fine for me.
02-17-2011, 04:52 AM   #7
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It could be the focusing mechanism on the lens. I had a Sigma lens once that started having focusing issues. It would not even hunt for the focus at a distance greater than macro. It was a screw driven lens too. But if i prefocused the lens it would catch at the last moment and focus. I also heard some additional noise coming from the lens too. Do you hear any additional noise coming from the lens? What distance is the object at when you are trying to get a focus?
11-20-2011, 08:30 AM   #8
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Hi everyone ... I am resurrecting this thread in search of some explanations/suggestions/advice:

I have just sold a Tamron 90mm/2.8 SP Di Macro to a fellow on this forum and he seems to be having similar issues with the AF of that lens.
I did not have AF problems with it before I sold it and it is in quite excellent condition mechanically, cosmetically and optically.
Here is a summary of the said reported problem by the buyer:

I think there is something quite wrong with the AF on the lens, I tested it on good daylight situation and sometimes it would not lock focus. It focus quickly to the object but then the focus confirmation in the octagon would just blink (this is around ~1m distance from subject I wasn't trying to AF on macro distance, not sure if this is normal behavior with this lens

I cannot confirm yet, but I think he uses a Pentax K-X.

If anyone woud contribute to solving this issue, it would be greatly appreciated.

Cheers.

JP

11-20-2011, 09:53 AM   #9
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QuoteOriginally posted by laurentpytel Quote
the camera juste dont try to find the focus... it does nothing...it seems to be lost ... and is not trying to go through the whole range to find the focus like my K7 did before

This statement pretty much mirrored my issue


It isn't exactly focus hunting, the focus is extremely fast but sometimes even on good daylight condition (I was metering 1/3000s f 4.0 @ ISO 100, so broad daylight) it has trouble locking focus on some subject.
It focused quickly to the subject (accurate focus too) but then it just stop there and wouldn't lock, the octagon focus icon in the VF would just start blinking indicating that its not focusing on anything, The camera just gave up and keep flashing the icon.
In that situation sometimes when I try to re-focus again (half way re-press the shutter) it would lock the focus right away, but most of the times it would attempt to make refocus adjustment (the focus would just move 1-2mm not hunting through entire focal length) but fails to lock again.
All this occurred on non macro distance and on good subject contrast.


Here is video of it, pardon the bad camera work
11-20-2011, 10:09 AM   #10
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Azzy: I fail to see much on this video but this could well be my poor eyesight too!

I am hoping someone here will jump in to help us out ... In the meantime I am trying to find out what's going on.

Talk later.

JP

Edit: Just a thought : could you test it using a high contrast "chart" such as the ones we use for AF accuracy?

Last edited by jpzk; 11-20-2011 at 02:42 PM.
11-20-2011, 01:24 PM   #11
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Sorry for the camera work, but if you turn the sound up you can find out whats going on
I was trying to focus on the toy that was ~60cm away, I was trying to focus on the feet which has pretty good contrast for AF to work with.
It focused quickly to it but if you turn the sound up you can hear that it would not lock focus, the lens would change the focus point probably 1-2mm away and give up again.
And a moment later on the same subject, lightning and setting it focused (see the end where you can hear the confirmation beep).

I see another user with similar issue here:
https://www.pentaxforums.com/forums/pentax-k-5-forum/127099-problems-my-tamron-90mm-macro.html

QuoteQuote:
I don't have the K5, but I had this lens for my K7. I bought it used but still under warranty. It had a similar focusing problem and consistently overexposed. I too heard something rattling around when I'd turn the lens over or shake it gently.
I hear slight rattle as well, not sure if it is related

Last edited by Azzy; 11-20-2011 at 01:30 PM.
11-20-2011, 02:44 PM   #12
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QuoteOriginally posted by Azzy Quote
Sorry for the camera work, but if you turn the sound up you can find out whats going on
I was trying to focus on the toy that was ~60cm away, I was trying to focus on the feet which has pretty good contrast for AF to work with.
It focused quickly to it but if you turn the sound up you can hear that it would not lock focus, the lens would change the focus point probably 1-2mm away and give up again.
And a moment later on the same subject, lightning and setting it focused (see the end where you can hear the confirmation beep).

I see another user with similar issue here:
https://www.pentaxforums.com/forums/pentax-k-5-forum/127099-problems-my-tamron-90mm-macro.html



I hear slight rattle as well, not sure if it is related
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