[vonBaloney]

Anybody who has this lens: I picked up one of these used in (seemingly) excellent condition, but am having trouble with the AF on my K-5. I know many have had to calibrate it for back-focus, and I did too (+8 seems to work best for me), but it is also doing this thing where it won't lock focus when using PDAF. Usually it happens when it is zoomed all the way to 200mm, but sometimes at shorter focal lengths also (much less often). What happens is that if it is not close to being in focus, it will get there and work fine and lock on. But if you take a second or third shot of the same subject (and so the lens is already where it needs to be), then it does not confirm focus, but does this mini-hunting thing: tiny movements back and forth around the target (usually just enough to get it defocused) and then it fails (green hexagon starts flashing).

I have no trouble with AF other than this lens, but then again I don't have many AF lenses either, and the only other one that is this fast is the Sigma 70/2.8 macro (which focuses fine).

Is there something wrong with this lens or is it just not playing nice with the K-5 AF system? (And I could expect it to do better with a K5-II or K-3?) I wish I had another body to test, but I don't (and this is a small town). I still can return it, trying to figure out what to do.

[nater]

The only time I handled one of these lenses in person was about 5 years ago, bought one used in very good condition. Would work intermittently on my K200D, but in a different way than you describe. Seemed like more of a camera-lens connection issue, where when it did work, it worked great, and when it didn't, I think it was almost like the camera didn't see the lens. Cleaned the contacts, etc. Contacted Tokina support, who mistakenly thought there was updated firmware/controller for the lens in Pentax mount (a common thing for other mounts like Canon, where third party lenses often stop working with more recent Canon bodies). Tokina in the USA had me send it in to their service center, but then they got word back from Japan that there was no updated firmware/controller after that, and so returned the lens to me. I ended up selling it at a steep discount (disclosing the problem) to someone who said they had no trouble with the lens on their body. I did like the lens, I thought the build quality was excellent and the image quality was very good. Not sure how much this helps you, but if you think it is a firmware/controller issue in your lens and you do contact Tokina support, make sure they can really get a replacement part before sending the lens in.

[vonBaloney]

The only time I handled one of these lenses in person was about 5 years ago, bought one used in very good condition. Would work intermittently on my K200D, but in a different way than you describe. Seemed like more of a camera-lens connection issue, where when it did work, it worked great, and when it didn't, I think it was almost like the camera didn't see the lens. Cleaned the contacts, etc. Contacted Tokina support, who mistakenly thought there was updated firmware/controller for the lens in Pentax mount (a common thing for other mounts like Canon, where third party lenses often stop working with more recent Canon bodies). Tokina in the USA had me send it in to their service center, but then they got word back from Japan that there was no updated firmware/controller after that, and so returned the lens to me. I ended up selling it at a steep discount (disclosing the problem) to someone who said they had no trouble with the lens on their body. I did like the lens, I thought the build quality was excellent and the image quality was very good. Not sure how much this helps you, but if you think it is a firmware/controller issue in your lens and you do contact Tokina support, make sure they can really get a replacement part before sending the lens in.

I asked Tokina, and they ignored my question and said the lens has been discontinued over 10 years now, there is no support. It doesn't seem to be a connection issue, and I did clean the contacts. It would probably be something loose to do with the AF mechanism. Which I could see, this thing has incredible torque when the AF engages. It is violent and quick when it is working. I need to find another body to borrow around here for a few minutes...

[Lowell Goudge]

Maybe you should take it off AF-C and put it on AF-S. Sounds like it is getting micro adjustments from the camera and it can't lock on focus from close by

[vonBaloney]

Maybe you should take it off AF-C and put it on AF-S. Sounds like it is getting micro adjustments from the camera and it can't lock on focus from close by

It is on AF-S

[uttam.hathi]

at-x pro for pentax has three lens basically, 20-35/2.8, 28-70/2.8 and 80-200/2.8, its coatins are dark save and except 28-70/2.8 angenieux version, there lies the issue guess the problem will not be there in a well lit object.
pls confirm this

[Odinz]

I have the 80-200 F2.8 that I have had for several years (mine was purchased new) and it behaves pretty much the same as yours does, at least until recently. I bought mine back when the K10 was still fairly new, it back focused a little bit, occasionally it would do the little micro-hunting and stall not in focus, and of course it was loud which it typical of all of my AT-X Pro lenses. When it did focus properly (about 75% of the time) it was really sharp. At F2.8 the whites really 'bloom' in bright light but that seems to be typical of most Tokina lenses so not unique to this one.

When I got the K20 all of the hunting and focusing issues got worse (good focus probably around 40-50% at least on the wider apertures). I could now at least adjust for back focus (+9) but it didn't seem to make much difference as, at least on mine, the amount of back focus would vary per the focal length. I sent it to Tokina and they told me that the lens was fine, it had been designed for film, not digital and there was nothing wrong with it. I did try the lens on the Pz-1P and the MZ-S and it did indeed seem to focus some what better, especially on the Pz-1P, so I kept the lens but used it much less.

When I got the K5 I tried it again, this time it was better than the K20 had been, but it still functioned about the same as it did on the K10, all of the issues remained, back focus, hunting etc. (In focus shots at around 75%).

Things all changed when I got the K3 last year. When I put this lens on the K3 all of a sudden there was no back focus issues (or very minimal) and it nails the focus nearly every time, it was like getting a new lens. There are still the little micro-hunting issues, although not quite as frequent and it eventually finds focus more often than not. Maybe this has to do with the three cross focus points, I don't know, but I find that I use it much more than I did before and it is definitely much more of a joy to use now.

I have not ever tried it on the K-01 as I converted that one to full spectrum, but after the results from the K3 my guess is it would probably focus just fine on that camera due to focusing directly off of the sensor.

Sorry for being long winded, but I guess to answer your initial question, it appears that your lens is functioning just as expected (or both of our lenses are off)

Steve

[vonBaloney]

Yes, just to clarify I'm talking about it doing this in basically ideal conditions -- outdoors in the sun. The problem does crop up a little more on low contrast/similar color subjects I guess -- it seems to have a hell of a time with tree trunks, wooden fence posts, mostly white birds, etc. And I'm taking single shots, letting go of the shutter, and then attempting another of the same subject, so it should either immediately confirm focus, or make a tiny adjustment and lock (which is how my other lenses would behave). This one will go tinyback-tinyforth tinyback-tinyforth tinyback-tinyforth tinyback-tinyforth FAIL (all stop, green hexagon blinking). The back and forth thing is exactly the same every time, very rhythmic, movements exactly the same size. It is like it is trying to make a smaller adjustment than the lens will allow for (even though it barely moves) so it keeps overshooting and then goes back again. Maybe they just made the gear in there too big -- not precise enough? As others have also noted, the torque on this thing is quite noticeable, it feels like it is going to jump out of your hand until you get used to it. (Maybe the body itself is not capable of making the small adjustment?) The problem is mostly prevalent right at 200mm, back off just a little and it usually works, but it still crops up here and there other times. When it works, it is sharp, beautiful images. And there is no physical problem with the focus -- if I manual focus, I can nail focus no problem.

I should point out that it will lock on OK using CDAF/live-view, but that's problematic also because both my K-5 and K-01 have that stupid "feature" where it will automatically stop down the aperture somewhat in bright light with live view (even during AF), so it ends up focusing with the aperture at f/5.6 (or whatever it is) and so if you are actually shooting wider than that the actual shot turns out blurry. I think this is a problem for any fast lens using CDAF -- just a design flaw there, not sure why I don't hear it complained about more. (If someone knows how to turn off that stopping down thing in bright light, let me know please.

Odinz, thank you for your comments, I'm actually glad to know someone else has had trouble with it like that. I suspect like you it is just something particular to this lens that makes it back-focus and behave strangely on these models -- the older AF systems are just not playing nice with it. Sounds like I need to get that K-3 or sell it to someone that has one. I just want to make sure it isn't actually broken before I sell it to someone, and make sure it is going to work ok with their camera. The copy I have looks almost mint, came in the box with the case, looks well-cared for, but it does also have an idiotic push-pull AF/MF clutch mechanism that could cause people to force the ring a bit (if it is in AF, and you want to put it back in MF, you have to find the *invisible* slot somewhere along the focus range which *moves* every time you focus -- really stupid).

[Odinz]

Yes, the manual focus clutch is definitely an odd one. It sounds like our lenses behave pretty much the same way so it is probably in the design. It can do that little hunting motion no matter what the lighting conditions are. As soon as it starts doing it (and it's always when you try to take multiple shots from approximately the same distance) I'll quickly point the camera at something close to move the focus and then point it back at what I'm shooting,

Thanks for mentioning the K5 / K-01 screens stopping down, I though that it was something that I had done to the settings, but even the Q7 and I believe that the K3 (I don't use live view much with this one) do the same thing. It is really irritating, but I have just grown accustomed to it.

[uttam.hathi]

I have the 80-200 F2.8 that I have had for several years (mine was purchased new) and it behaves pretty much the same as yours does, at least until recently. I bought mine back when the K10 was still fairly new, it back focused a little bit, occasionally it would do the little micro-hunting and stall not in focus, and of course it was loud which it typical of all of my AT-X Pro lenses. When it did focus properly (about 75% of the time) it was really sharp. At F2.8 the whites really 'bloom' in bright light but that seems to be typical of most Tokina lenses so not unique to this one.

When I got the K20 all of the hunting and focusing issues got worse (good focus probably around 40-50% at least on the wider apertures). I could now at least adjust for back focus (+9) but it didn't seem to make much difference as, at least on mine, the amount of back focus would vary per the focal length. I sent it to Tokina and they told me that the lens was fine, it had been designed for film, not digital and there was nothing wrong with it. I did try the lens on the Pz-1P and the MZ-S and it did indeed seem to focus some what better, especially on the Pz-1P, so I kept the lens but used it much less.

When I got the K5 I tried it again, this time it was better than the K20 had been, but it still functioned about the same as it did on the K10, all of the issues remained, back focus, hunting etc. (In focus shots at around 75%).

Things all changed when I got the K3 last year. When I put this lens on the K3 all of a sudden there was no back focus issues (or very minimal) and it nails the focus nearly every time, it was like getting a new lens. There are still the little micro-hunting issues, although not quite as frequent and it eventually finds focus more often than not. Maybe this has to do with the three cross focus points, I don't know, but I find that I use it much more than I did before and it is definitely much more of a joy to use now.

I have not ever tried it on the K-01 as I converted that one to full spectrum, but after the results from the K3 my guess is it would probably focus just fine on that camera due to focusing directly off of the sensor.

Sorry for being long winded, but I guess to answer your initial question, it appears that your lens is functioning just as expected (or both of our lenses are off)

Steve

thus then the issue is of the camera, software substandard, not an lens issue, designed to keep third party lens out, i have 2 at-x pro 28-70/2.8 and 20-35/2.8, as known 28-70/2.8 is not an issue but 20-35 is, am presently still on k-7 have used k-10, k-r

[nater]

thus then the issue is of the camera, software substandard, not an lens issue, designed to keep third party lens out...

I don't think that's exactly right. From my understanding, there have been fewer major incompatibilities with third party lenses on Pentax bodies than on Canon or Nikon bodies, respectively. While I think it would be great if every camera maker opened up their AF protocol and worked closer with third parties, I think the reality is they're primarily concerned with their own, first party product line. While I'm sure they appreciate the third party lenses to an extent (since they fill in holes in their lineups and create a larger 'family' of products), the third parties are also competition that they might see as 'taking away their profits' (an oversimplified view, but I assume some might look at it that way). There isn't much immediate incentive for Pentax, Canon, Nikon, etc. to maximize compatibility with third-party AF lenses, especially older ones, but I wouldn't call it substandard software, just proprietary, and they're not designing to keep third party lenses out so much as just not giving them any significant priority.

[uttam.hathi]

i agree but the data of third party lens to be fitted into the software seemingly was inappropriate in the bad days of pentax-hoya