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06-06-2011, 08:05 AM   #1
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AF inconsistency - need advice

Hi there. I recently upgraded to K-5 from a K10 and I have a problem. My main lens is a Tamron 17-50mm f2.8. The lens focuses spot on on my K10 but for some reason K-5 struggles to focus properly. There is a huge difference in AF adjustment between indoor light (-10) and outdoor light (+4). Also almost half of the pictures I'm taking outdoors are out of focus although I always get the focus confirmation before taking the picture. And by out of focus I mean really really blurry pictures from f2.8 to f8.

So far it seems that the camera is faulty but what puzzles me is that with my other lenses, Pentax 55-300 and Sigma 10-20, the K-5 has no problems focusing. I get really good focus with all 3 lenses on my K10 but somehow K-5 doesn't like my Tamron. I always use center focusing and upgraded to firmware 1.03 as soon as I got the camera (and I'm sorry now I didn't try the lens before the focusing adjustments that came with the firmwares...)

Any idea what the problem is? Should I send the camera back? Is there a way of downgrading the firmware? Any thoughts are appreciated. Thank you.

06-06-2011, 01:15 PM   #2
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Well if your camera works with two lenses then maybe it's time to say goodbye to the Tamron.
06-06-2011, 01:41 PM   #3
Ash
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3rd party lenses seem to have more issues with focusing on the K-5. The only way to resolve it is to have the lens and body calibrated by a service person.
06-06-2011, 04:52 PM   #4
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RonHendriks1966, did you notice that the OP wrote that the Tamron focused just fine with his K10D?

Clearly there is a problem with the Tamron & K-5 combination and it is not easy to determine where the cause of the problem is.

However, given
  • the K-5's shoddy AF history (with at least one bug remaining),
  • the dependency of your results on light temperature, and
  • the fact that the Tamron worked fine on your K10D,
I'd start the trouble shooting with the K-5.

Third-party or not, a camera's AF should not behave like that. The Tamron lens is highly regarded, not only by members of this forum, it has worked with many, many Pentax DSLR models before.

06-06-2011, 06:37 PM   #5
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The Tamron needs to be re-calibrated for focus. An issue that crops up with this lens even with other camera makes. The Tamron is a nice and sharp lens but build quality is nothing to shout about.
There is nothing overtly wrong with your K-5.
06-07-2011, 06:59 PM   #6
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The K-5 does have inconsistent AF with V1.03. I beleive this is a side effect of them bodging up 1.03 in order to improve the Low light AF performance.


QuoteOriginally posted by Nicks Quote
Also almost half of the pictures I'm taking outdoors are out of focus although I always get the focus confirmation before taking the picture. And by out of focus I mean really really blurry pictures from f2.8 to f8.
Are you sure this is due to being out of focus? At f8 a bit of frotn or back focus should fall within the DOF

I've been getting some intermittant soft images in bright daylight even at 1/2000s and smaller apertures towards F8. It's a bit random and I'm wondering if it's due to the Anti-shake not latching quick enough. I normally leave the Anti-Shake on all the time but I'm purposely turning it off on my next shoot, unless I specifically need it.
06-07-2011, 07:48 PM   #7
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QuoteOriginally posted by Smeggypants Quote
It's a bit random and I'm wondering if it's due to the Anti-shake not latching quick enough. I normally leave the Anti-Shake on all the time but I'm purposely turning it off on my next shoot, unless I specifically need it.
I've actualllly set up a "user" mode similar to the TAV mode-with SR off..and I have the impression that my focus accuracy improved during bright light shootings when SR has no real importance.

Andras

06-07-2011, 09:17 PM   #8
Brooke Meyer
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I'm feeling guilty.

I have two K-5s, both on 1.03. My DA12-24, Tamron 28-75, DA 50-135 and Sigma 100-300 all work fine. This is from last Sat. with my new used open box K-5 and 4 year old Tamron. Th 1/160 sec shutter speed is an attempt to offset the florescent lights color flicker. In late afternoon, it really is that bright.

Last edited by Brooke Meyer; 08-31-2011 at 11:05 PM.
06-08-2011, 01:34 AM   #9
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Thank you all for your comments.

"The only way to resolve it is to have the lens and body calibrated by a service person."

If I send the body to be calibrated with one lens, is this going to affect the focus with my other lenses?

"The Tamron needs to be re-calibrated for focus."
"Are you sure this is due to being out of focus? At f8 a bit of frotn or back focus should fall within the DOF"

The lens is working really well on my K10, as my other lenses. I really don't think it needs calibration. Also FF and BF is only part of the problem. K-5 really struggles acquiring focus with this lens. Sometimes I focus on a close object <3m, I take the picture then focus on a distant object >50m and I get the focus confirmation with no actual focusing action happening?! I check the second picture and I can clearly see the same close object in focus at the bottom of the picture but not the distant object I actually focused on. I have to release and press the shutter one more time to get the correct focus in this situation....And I always use center spot focus so there's no room for mistakes here.

I'll have to see what happens with the SR off...
06-08-2011, 02:41 AM   #10
gtl
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Dumb question but is your K5 is perfect with other lenses?

QuoteOriginally posted by Nicks Quote
Thank you all for your comments.

"The only way to resolve it is to have the lens and body calibrated by a service person."

If I send the body to be calibrated with one lens, is this going to affect the focus with my other lenses?

"The Tamron needs to be re-calibrated for focus."
"Are you sure this is due to being out of focus? At f8 a bit of frotn or back focus should fall within the DOF"

The lens is working really well on my K10, as my other lenses. I really don't think it needs calibration. Also FF and BF is only part of the problem. K-5 really struggles acquiring focus with this lens. Sometimes I focus on a close object <3m, I take the picture then focus on a distant object >50m and I get the focus confirmation with no actual focusing action happening?! I check the second picture and I can clearly see the same close object in focus at the bottom of the picture but not the distant object I actually focused on. I have to release and press the shutter one more time to get the correct focus in this situation....And I always use center spot focus so there's no room for mistakes here.

I'll have to see what happens with the SR off...
06-08-2011, 03:46 AM   #11
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my K5 had inconsistent Af with differing lenses..so your not alone ...and it wasn't Af fine adjust either..but shifting focus as the FOV widened .. with a screw drive prime it was spot on...pentax/sigma HSM/SDM...not too good in low light ....
06-08-2011, 05:40 AM   #12
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"Dumb question but is your K5 is perfect with other lenses?"

Yes, as I said, my K-5 is ok with all my other lenses. And my Tamron lens and my other lenses are all perfect with my K10D body.........The problem is only with the K-5+Tamron 17-50 combination.
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