[Ray Pulley]

I'm a new K-5 owner and I'm disappointed with the AF performance when using Tamron 17-50 @ F2.8, using center focus point zoomed out to 18mm. Most times I get image out of focus if I zoom out. Stepping down to F5.6 resolve the issue. For some reason, sometimes, the camera "doesn't bother" the refocus after zooming out if the aperture is below F4.

My test:

1. Focus on an object @ 50mm F2.8. - I can hear the AF motor focusing.
2. Zoom out to 18mm, keep F2.8, point center focus on same object - The focus indicator will lit but no focus correction - the result, image is in bad focus.
3. Focus on an object @ 50mm F5.6. - I can hear the AF motor focusing.
4. Zoom out to 18mm, keep F5.6 point center focus on same object - I can hear the AF motor focusing, image is in good focus!

Is this a lens flow or camera flew?

There are many reports of focusing problems with the Tamron 17-50 on many different brands including some reports on this forum.

I do not exactly understand your test above, but most zooms are vari-focal and they will not hold focus if you focus at one zoom level and then zoom to another without re-focusing.

If the lens obtains sharp results at various zoom settings after re-focusing each time after you zoom, then there is nothing wrong.

If your camera gets sharp results with another lens, your camera is likely ok.

The last possibility is that the Tamron and your K5 are not well calibrated together, but Tamron is not going to calibrate your K5 and Pentax is not going to calibrate your Tamron.

My bet is that, like many others have reported, the Tamron is at fault, but you would need to do more testing to be sure.

Ray

[philbaum]

I'm a new K-5 owner and I'm disappointed with the AF performance when using Tamron 17-50 @ F2.8, using center focus point zoomed out to 18mm. Most times I get image out of focus if I zoom out. Stepping down to F5.6 resolve the issue. For some reason, sometimes, the camera "doesn't bother" the refocus after zooming out if the aperture is below F4.

My test:

1. Focus on an object @ 50mm F2.8. - I can hear the AF motor focusing.
2. Zoom out to 18mm, keep F2.8, point center focus on same object - The focus indicator will lit but no focus correction - the result, image is in bad focus.
3. Focus on an object @ 50mm F5.6. - I can hear the AF motor focusing.
4. Zoom out to 18mm, keep F5.6 point center focus on same object - I can hear the AF motor focusing, image is in good focus!

Is this a lens flow or camera flew?

I don't have the Tamron, but your report reminds me of a known problem of the F4 Sigma 10-20 UWA. Several folks, including me, have experienced focus problems at the 10mm end, but fine performance at the 12 to 20mm range. It seems that with the compaction of edges in extreme wide angle zooms, that its difficult for dslrs to find the necessary contrast areas to confirm focus.

I think such problems are not a problem with the camera so much as the lens characteristic. I've learned to work around the problem with the otherwise fine Sigma lens, and i think you'll have to remember that trait of your Tamron lens as well. I have a friend who does have the Tamron, and have seen many sharp images from it - i'll ask him about the 18 end when he returns from a recent trip.

[zici]

That's my first post here, so first of all - Greetings to all of pentaxforums.com members!
I've recently upgraded to K-5, and love it for all, but the focusing issues in low light. However, I've recently been trying to workaround the front focus in low-light issue, and found some weird solution, before I've actually read that post.

I've uploaded 1.11 firmware from Japanese site into K-5 now. I will test FA43 tomorrow again.

It's silly - but with in-camera flash all photos with FA43 are good. But I don't like flash. Outside - at the streets - no any results...

I will retest and inform here...

It's just about the same for me.
While the camera confirms focus lock-on, it often results in FF when previewed. The AF accuracy results improve when using either the external flash unit, or even the built-in flash - the shots are spot-on. I know that makes no sense, as the flash unit doesn't take a part in focusing process, but that simply works for me. Running 1.11 too, and setting WB to flash. Anyone else experienced such awkward behaviour?

Cheers

[ogl]

It's just about the same for me.
While the camera confirms focus lock-on, it often results in FF when previewed. The AF accuracy results improve when using either the external flash unit, or even the built-in flash - the shots are spot-on. I know that makes no sense, as the flash unit doesn't take a part in focusing process, but that simply works for me. Running 1.11 too, and setting WB to flash. Anyone else experienced such awkward behaviour?

Cheers

1.12 firmware solved my problems. It's strange, but...
1.11 was better than 1.03 too.

[cbope]

1.12 firmware solved my problems. It's strange, but... 1.11 was better than 1.03 too.

Wow, strange. A newer software actually fixed some problems... :P

(I work in software development)

Note: I updated to firmware 1.12 when it came out last week, but have not shot any pics yet. The only known problem I experienced is the well-known bounce flash over-exposure issue.

[Jeff Charles]

I'm a new K-5 owner and I'm disappointed with the AF performance when using Tamron 17-50 @ F2.8, using center focus point zoomed out to 18mm. Most times I get image out of focus if I zoom out. Stepping down to F5.6 resolve the issue. For some reason, sometimes, the camera "doesn't bother" the refocus after zooming out if the aperture is below F4.

My test:

1. Focus on an object @ 50mm F2.8. - I can hear the AF motor focusing.
2. Zoom out to 18mm, keep F2.8, point center focus on same object - The focus indicator will lit but no focus correction - the result, image is in bad focus.
3. Focus on an object @ 50mm F5.6. - I can hear the AF motor focusing.
4. Zoom out to 18mm, keep F5.6 point center focus on same object - I can hear the AF motor focusing, image is in good focus!

Is this a lens flow or camera flew?

Although the problem was not the same as the one you are experiencing, I had a Tamron 17-50 that did not focus correctly on my Nikon D90. The lens was new, but rather than return it to B&H, I sent it to Tamron to be checked and repaired. They turned it around quickly, and the lens focused perfectly after I got it back.

Not knowing if the problem is the camera or the lens, it might be worth having Tamron check it.

Jeff

[ogl]

Wow, strange. A newer software actually fixed some problems... :P

(I work in software development)

Note: I updated to firmware 1.12 when it came out last week, but have not shot any pics yet. The only known problem I experienced is the well-known bounce flash over-exposure issue.

It's strange, because my newly purchased K-5 was with 1.01 firmware.
1.03 couldn't help with AF accurancy. 1.11 made a big leap.
1.12 help me a lot with FA43.

But 1.11 and 1.12 have no any official info about AF improvement.

I didn't tested FA*24 и FA77 with 1.12 yet.

[cbope]

But 1.11 and 1.12 have no any official info about AF improvement.

As I mentioned in one of my earlier posts... it's a rare thing to list every single improvement in the release notes for a software/firmware update. In this case, it seems to be an extreme case of unmentioned fixes... but this is no surprise to someone (me) who works in software development. Many times things are rushed out before engineering has time to document all the fixes/changes. This is nothing new... and far from the last time something like this happens.

[rawr]

it's a rare thing to list every single improvement in the release notes for a software/firmware update.

Ricoh actually do a pretty good job documenting their firmware changes....eg:
GR DIGITAL III firmware / Software Downloads / Digital Camera | Ricoh Global
including PDF downloads with updates to the camera manual if required.

Pentax would do well to follow their colleagues example.

[rjcassara]

If they specifically coded instructions to address AF issues, they would definitely document it. There's absolutely no reason not to.

Because these types of AF issues seem to be sporadic for people, I think it's more likely that updating the firmware essentially does a factory reset of the camera which flushes out any weird bugs that may be affecting the AF system. (possibly the flash exposure as well).

I've been having trouble with focusing the FA43 on my K-5 (running 1.03), so I'm hoping I get a similar improvement with the firmware.

[philippe]

Strange or not, after I performed the upgrade from 1.11 to 1.12, I had to overdo the AF adjust for all my lenses. At the time, these AF adjusts were done for me at the Pentax service centre, perhaps the way they do it might be flushed by the update, I do not know and "...frankly my dear, I don't give a damn..." because all is working fine now. BTW that Spider LensCal is a good 'toy'!
I haven't tested the flash thing.

[westmill]

Yup ! firmware 1.12 deffo alters the focusing ! My Tamron 17-50 needed -5 correction. Its now at 0.... The lens really needs to be sent for calibrating though.
At 50mm its optical peak is at -5 while the 17mm end reaches its peak at plus 5. So I set it in the middle for the best compromise. Its not toooooo bad though.
Another thing i picked up on, is the focus is far more active, as if there has been more focus steps added. Thats how it seems anyway. As i focus on certain objects
in the living room, a slight move to a different point alters focus. Before it seemed there needed to be quite a big deph differance before the camera would refocus.
This alone, told me focus acuracy was a tad second rate at best. Now... with 1.12 the slightest difference in depth and the focus responds.
However.. Ive also found low light focus has gone a bit worse. It locks ok but takes considerably longer than it did.
Quality control for both Tamron Sigma and pentax lenses needs improving badly. Its not unusual at all for photozone to return lenses because they are just
so badly calibrated, they are deemed unfit for testing ! This can happen to any lens of any make of course, but these 3, it seems almost normal.
Photozone tried 3 different examples of the pentax 50-135 2.8 before they got a sample that was even testable. And even that was flawed at the 135mm setting.
The times ive read test reports ending with.... A great and worthwhile lens, assuming you can find a good sample !

[RGold]

Here are some examples.

First one is ok. But the other 2 are not clear even tough the focus indicator lit.

[Pa. Patriot]

Holy back-focus, Batman.

[RGold]

Just got the Pentax 16-45 f4. Took more then 100 test shoots with no issue at all! Good lens. I'm going o return the Tamron 17-50. I guess Pentax is working better with Pentax...