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10-24-2013, 04:38 PM   #1
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Tokina AT-X 828 AF PRO 80-200mm 2.8

I've paired this beautiful lens with a K30 for my kids sporting events over the last year. No matter the lens correction I can't seem to get a decent AF lock...even in good lighting . After a decent 1 hour activity I wind up deleting 90% of the photos for severe back focusing. Sadly this lens produces amazing photos in MF and sometimes in AF....but I'm so frustrated i'm about to say goodbye. Any feed back with this or other Tokina lens would be appreciated.

Joe....Desperate in NH!

10-24-2013, 05:59 PM   #2
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Does your camera back focus with other lenses? Perhaps the correction is beyond the level the camera can adjust for. If you have to adjust your other lenses, perhaps you can send your K30 in to be adjusted. I sent my K-r in because, with my 50/1.4, I couldn't get good focus at maximum adjustment. After I got it back it worked much better. It was still not as perfect as my K100D, but it did work with minor adjustments. Also, just checking, are you using this on a tripod with IS turned off? IS isn't really for sports, and having it turned on while on a tripod will create blur.
10-24-2013, 09:59 PM   #3
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Hi
Please post a few example photos with the exif intact.
That should help get a few opinions on the problem.
10-24-2013, 10:04 PM   #4
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Hi jezzeppi,

Has this lens ever focused well with your K30 body? Can you manually focus the lens and get sharp images?
Are the aperture blades snappy with good spring tension at the aperture lever on the back of the lens?, and do they retract fully when the lens is wide open? Do you get any anomalous badly exposed shots? Does the VF ever look darker than you'd expect when you're activating AF and framing the subject?
Have you cleaned the contacts and checked them against a straight edge for height?
Have you tried returning the micro focus correction to 0 and trying it again without correction?
Have you tried this lens on any other bodies, and how does this body focus with other lenses -- any correction needed?

I have this lens (the second version), and it has always worked like a charm on all of my bodies. There are a number of things that can go wrong with a lens, but many can at least be diagnosed, if not fixed by a reasonably handy user.

Scott

10-26-2013, 06:05 AM   #5
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Ok...I'll put together some examples and get them posted. Manual focus is perfect. My other lens (50mm 1.4 & 10-17mm) are spot on. Everything looks fine in the View Finder and I don't seem to get unexplained badly exposed shots. I'll have to check the connectors and shoot some photos on my old ist ds to seem if it has the same problem. I've fiddled with the lens correction many times in both directions...never with satisfaction.
10-26-2013, 11:25 AM   #6
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Sometimes old lenses from third parties don't work well on new bodies. This was a big problem with Sigma lenses designed for Minolta AF. I read on an eBay ad that this lens has trouble with some newer Nikon bodies, maybe you're having a similar issue with the K-30. I would be interested to hear from other owners of this lens.

If you look on this post someone said the Lens needs to be rechipped to work on a new body. The person providing the solution said that his lens was fixed for $83.

http://www.fixya.com/support/t1277260-tokina_80_200_2_8_x_compatibility_issue
03-23-2014, 06:04 PM   #7
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Just spotted this thread and thought I'd relate my recent experience with this lens on a K5.

Bought the lens off ebay and it arrived in what looks like near mint condition (wonderful construction quality!), so very eager to see what results it turned in.

Initial shots looked fine, and nicely sharp, but they were taken between f/4.5 and f/8 and, as it turns out, the depth of focus was masking a fairly severe back-focusing issue, revealed on shots taken wide open.

Fine focus adjustment (+10, the maximum) was not enough to bring it in, and I was therefore worried that this would prove a difficult issue to resolve...

However, I found references to the possibility of applying auto-focus correction via a debug mode on the camera, and after a couple of hours yesterday morning now have the lens seemingly dialled in to my body, and all other lenses adjusted to cope with the extra 'correction' now applied. I can now auto-focus with some confidence.

If you have a PC (Windows) then the PK Tether method will allow entry to debug mode, if you are on Mac (as I am), then the means of access means placing specific files at the root level of a memory card and then turning the camera on with the card door open. See Resurrecting Pentax Firmware Hacking (first three pages), and Ricehigh's walkthrough process for tweaking auto-focus correction for more details.

Usual caveats apply though... debug mode is not meant to be accessible on K5 or any other pentax camera, so involves using reverse engineered methods of entry, and then exposes commands that could adversely affect other operation of the camera. If you do decide to try this then you do so at your own risk, and any error on your part could mean costly repair, or a new camera body.

For me it worked, and I now have a lens that I thought would be only marginally usable at f/5.6 or smaller, is now usable from wide-open.

Cheers


Rob

(aside: Pentax is very poorly supported in Thailand, verging on 'not at all'... at best it is 'difficult', and usually dependant upon some unofficial camera tech to get anything done... If there is anyone who knows different, I'd love to learn of reliable pentax support here)

Last edited by roblgs; 03-23-2014 at 06:09 PM. Reason: Moved the aside to the bottom
03-24-2014, 06:57 PM   #8
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Thanks for the insight. My K30 was stolen on trip to NYC recently..... good news is this caused an upgrade to a K3! Bad news...same problem with the Tokina. I hate the idea of correcting the camera rather then the lens. But I do love the construction of it. I'll read the recommended fixes and report back....... thank you

03-24-2014, 09:25 PM   #9
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Hi,

Sorry to hear about your loss, but then the cloud came with a silver lining in the form of a K3.

If you do decide to take this route you need to be aware that any correction applied in debug mode is global, and so affects every lens you use.

Mine needed +50Ám to be added in debug, so this plus the +10 auto focus adjustment on the camera in normal operating mode equates to an effective +15 for this one lens.

In order to compensate for the debug offset I also set a -5 auto focus adjustment for ALL lenses, to bring them back into focus... Any separate adjustment needed for any other individual lens would also need to be adjusted to compensate for the debug correction.

Every 10Ám in debug is equivalent to 1 step in the standard auto focus adjustment.

I have a tamron 90mm macro that was exactly 0 correction prior to my changes... that now requires -5 on the normal focus adjustment.

This would not work if you have one lens with extreme back focus, and one with extreme front focus. All it does is to shift the +/-10 scale towards one direction or the other, it does not increase the adjustment range at all, it remains +/-10, but you've moved the centre point of the range, in my case to allow correction of more extreme back focus.

Good luck.
04-22-2014, 12:21 PM   #10
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Thanks for pushing me in the right direction roblgs! Major difference right off the bat. I'll have some out door soccer games coming up to really test it out.
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