[slip]

I have a Sigma 100-300 and had a K5iis. I now own a K3 and here are my findings/experience:

With the K5iis, no matter what I tried, it did not play well with the Sigma, I, too experienced severe back focus on many many shots even after calibration. On occasion I would get a keeper (I'd guess about 50% of the time) but it required a technique of focus, stop, refocus if the subject lacked contrast such as animal fur etc. High contrast/texture objects it generally did very well with, but if that high contrast/texture was behind my subject, the lens would lock onto that object like dog on a scent. I'd have to recompose, focus intentionally on an near object, then refocus and hope that the lens would choose my subject. The problem was that often I could not tell in the viewfinder, only once I could see the image at 50-100% on my computer. I have posted several rants about this very issue over the years, but I won't link them here...lol

On my K3, after all my frustrations with the K5iis, I have been much more thorough in my investigations and slightly happier with the results. My first impression is that the smaller center AF point of the K3 was a BIG help, right off the bat. The 100-300 was more consistent and reliable. So much of your frustration is due to the "poor" AF system of the K5ii(s) bodies.

The next step took about 3 hours and a test target/calibration ruler. Using combinations of LV, MF and AF I discovered some quirks of my 100-300. At 300mm and f4 at less than 10m I needed a +8 adjustment. At 300mm and about f8 at the same distance my adjustment was 0! I tried it at 50m with a 300mm focal length and found that my needed adjustment was also based on aperture, ranging from +7 at f4 to -2 at f11. Essentially, subject distance AND aperture affected front/back focus response. I have no clue why or what causes this so I'm chalking up to the fact it's a legacy lens and there's probably been some movement of elements or what not. I've just resigned myself to "missing" some shots and if I can, trying to tweak focus manually.

Here's the other thing I noticed, at least in my copy, the physical focusing mechanism has some play. If I had to guess it would be the equivalent of about 2 feet (.6m) of depth of field as we get to the mid to long focus distances. Close to minimum focusing distance, it's a little more accurate . This means that the lens will tell my K3 body it is focused at say 25m when it can actually be 24.3 to 25.6m. At 300mm and f4, that's the difference between a nose in focus and the tail being in focus instead. It was even greater if I have the quick shift ring in MF mode and the body in AF. There's probably 3-4ft (1-1.3m) of play, especially close to infinity.

My conclusion is that the Sigma 100-300 is a great lens optically, but it doesn't really play well with the K5 series because of the HUGE auto focus points. It could be sample variation, because others have raved about how well this lens performs on their bodies, but you sound like you have a quirky copy like mine.

The "only" thing you can do is be aware of the issues and develop techniques to try and compensate, but for quick action scenes you may not have that luxury. You may also consider going to a K3. Lately I've been using 9 point AF-C and shooting in 3-4 shot bursts and that seems to have upped my keeper rate. Single shot and AF-S is still inconsistent.

In terms of service, CRIS Camera told me last year that there were NO parts even available for service or maintenance work, so there was nothing they could do to help. They are a Sigma Authorized Repair Center, so they would probably know. I haven't talked to them recently after my marathon testing session in January, but I'm not sure if anything can be done for the focus mechanism play anyway.

this is the problem with my Sigma 70-200 2.8 in a nut shell. I used the dot tune method and it told me +10. Set it there and it didn't help. tried for hours with different micro adjustments and I ended up using -4. Go figure!
the close to mid distances are better (but not until F4) and the very long distances is much a write off. it is too old to get fixed according to Sigma, so I have to live with it as is.
you might have to do the same

good luck

Randy

[daimonwn]

So you're saying that with AF adjustment set to either extreme, the lens performs the same?

Yes. Even if I make adjustment and for lens (+10) and for body (+10) together (total +20 or -20) result is a same... it's absent.
With another lenses adjustment is working. Problem only with Sigma 100-300.

[Edgar_in_Indy]

Yes. Even if I make adjustment and for lens (+10) and for body (+10) together (total +20 or -20) result is a same... it's absent.
With another lenses adjustment is working. Problem only with Sigma 100-300.

I've owned a couple copies, and one did not need any adjustment, and the other I was able to adjust successfully.

Are you in the US? If so, and the lens is otherwise a good copy, maybe you should consider sending it to Sigma in New York for calibration to your body.

[daimonwn]

Are you in the US?

Nope, I'm from East Europe. And my official Sigma service centre can calibrate only for Canon and Nikon bodies. Pentax? Hahaha what is a Pentax?

---------- Post added 05-19-16 at 10:26 PM ----------

and the other I was able to adjust successfully

by yourself or by service centre?

[Edgar_in_Indy]

Nope, I'm from East Europe. And my official Sigma service centre can calibrate only for Canon and Nikon bodies. Pentax? Hahaha what is a Pentax?

Bummer. The Sigma service center in New York has provided incredible service any time I dealt with them.

by yourself or by service centre?

I was able to calibrate my old 100-300mm f4 myself. Lenses which I had calibrated at the service center include my Sigma 30mm 1.4 and 50-150mm f/2.8. It was free since they were under warranty. I had to send the 50-150mm in for a firmware update, so I figured why not. The calibration was perfect, BTW.

My current 100-300mm f4 and my Sigma 85mm 1.4 were both perfect without any calibration adjustment.

[nomadkng]

Yes. Even if I make adjustment and for lens (+10) and for body (+10) together (total +20 or -20) result is a same... it's absent.
With another lenses adjustment is working. Problem only with Sigma 100-300.

There's another thread on here somewhere where it was revealed that the first(?) generation 100-300 f4, the one with the checkerboard-ish type grip has batches that suffer from almost uncorrectable back focusing at f4, but sort themselves out by f6.3 or something like that. Edit: I found the quote

There are two batches of the 100-300 Sigma. At least some lenses of the older batch are known to have a "focus jump" at f6.3. It means that the lens will show severe backfocus from f4-f5.6. From f6.3 onwards the lens will focus correctly. They fixed that issue in the newer batch of lenses. You can distinguish the two batches by the look of the rubber on the focus- and zoomrings.
Old: http://www.lenstip.com/aparaty_image/2190_sig100-300_1.jpg
new: http://www.dyxum.com/images/Lenses/269/269_1.jpg

I sold my 100-300 referenced in this thread shortly after reading this insight. The new owner loves it, and claims he hasn't had any issues with it. That's awesome for him, but I tend to think he may not be pushing the lens to the limits like I normally do in my shoots.

Additionally, I did purchase a newer version 100-300 (straight ribbing) to replace the older one. In my personal experience has shown that it indeed is far more consistent and can be calibrated within tolerances. On my K3 it was a -2, on my K1 it's a -6.

this is the problem with my Sigma 70-200 2.8 in a nut shell. I used the dot tune method and it told me +10. Set it there and it didn't help. tried for hours with different micro adjustments and I ended up using -4. Go figure!
the close to mid distances are better (but not until F4) and the very long distances is much a write off. it is too old to get fixed according to Sigma, so I have to live with it as is.
you might have to do the same

good luck

Randy

I wonder if there were similar gremlins in the 70-200 production runs?

[jeallen01]

I had my 2nd generation 100-300 F4 repaired by Sigma Imaging in the UK last August - they actually managed to get the critical PWB assembly from Sigma in Japan (even the UK service manager was very surprised about that himself!) and fixed the lens.

However, I was still having problems with the K-3 after that and finally sent it back to the Pentax UK service centre (Johnsons Photophia Ltd in Newcastle under Lyme) for a full service, with some samples of problem shots. Did not have the opportunity to try it out again with the Sigma until a few weeks ago - and now it generally nails the focus point very well at 200-300mm (with the 1.4xTC on it as well) at "infinity"- and without ANY adjustments to either the K3 body or the lens. Much, much better now - although it obviously does the long focus swing if you get the basic distance setting incorrect or it is aimed at blank sky :-()

Like slip, I'm mainly using 9-point AF-C and shooting in 3-4 shot bursts on the K-3 with the 100-300 F4.

I now use my very early (and never serviced) 100-200 F2.8 on the K-5 only, and that does work quite well also.

[VoiceOfReason]

After adjusting it to -4 on the K3, -3 on the K1 I ended up posting examples. I was the new owner. It was as sharp as my 60-250 and my 150-450 wide open, but there was simply too much overlap in my lineup after I got the 150-450. Once you adjust it out (if you can) it is sharp enough to see the pixel edges zoomed in, even wide open. I was torn between trying a trade for an FA31 or Sigma Art 35 with it or the 60-250, but WR won out in the end. It was really close because this one was great on the K1 where the 60-250 had pretty bad vignetting.

[RJH]

This is now a very old thread but I've decided to add to it not because anything I say will contribute materially to the discussion but, rather, to offer some praise where praise is due.

I own a "first version" copy of this lens and it exhibits the the somewhat bizarre focussing issue described well by mherger. If the aperture selected is f7 our above it nails pdaf focus every time. If it is set below that, focus will never be achieved. Note that it is possible to select an aperture smaller than 7, lock focus, select a wider aperture, and take a perfect shot ( while using back button focus) - but that is of course clumsy.

Back to the point, I think I would probably still be scratching my head about this behavior without the explanation that I found on this forum. Encouraged by mherger's success at having his lens repaired I contacted the local agent (NZ) about the possibility of a fix. They suggested that, for NZ$75 plus courier each way, they would take a look at the lens.

Forewarned by all the helpful discussion here, I was able to point them to this thread and suggested that, before I risked the lens to a courier, they might like to check with Japan to see if a fix was available. After checking with Japan they informed me that no repair was possible.

Undaunted I contacted mherger , who promptly replied to my questions. Since his dealer HAD managed to fix his lens I emailed them. I received a prompt and polite reply from Michèle Kückens at OWY informing more that they could only handle repairs from within Switzerland.

I wrote back explaining why they had received an enquiry from the far side of the world and thanking them for their response. There I expected the master to rest, however this morning I received another email from OWY. In that email, Michèle apologised for the delayed response and explained that OWY had searched for a fix but that a copy of the firmware was no longer available.

So here's the point. Without this forum I would never have completely understood the problem. Without mherger's prompt reply I would not have known of a company with potential fix. Without the exceptional service from OWY I would have been considerably less happy with the unsuccessful outcome which I have finally accepted.

So praise where it is due and thanks to all along the way.

[Class A]

...but that a copy of the firmware was no longer available.

Shouldn't it be possible to read the firmware from an updated copy of the lens?

Isn't it the case that some Pentax cameras support reading the lens' firmware and writing it to an SD card?

[RJH]

Shouldn't it be possible to read the firmware from an updated copy of the lens?

Isn't it the case that some Pentax cameras support reading the lens' firmware and writing it to an SD card?

I'd be really interested if anyone has experience doing that!

[Class A]

I'd be really interested if anyone has experience doing that!

I only read the lens EEPROM ("LENS ROM") containing the AF microdadjust data with my K100D.

I'm not sure whether the K100D supports reading the lens' firmware.

In this older post you can see a screen of the debug menu of the K7 which clearly seems to support a lens firmware update (for the lens CPU). I don't know if it also supports reading the lens firmware.

Hope you'll find someone who may help you with any further steps. It would probably not be a bad idea to post to the "Deactivate SDM" thread as posters in there will typically have experience using the debug/service menu.

[RJH]

I only read the lens EEPROM ("LENS ROM") containing the AF microdadjust data with my K100D.

I'm not sure whether the K100D supports reading the lens' firmware.

In this older post you can see a screen of the debug menu of the K7 which clearly seems to support a lens firmware update (for the lens CPU). I don't know if it also supports reading the lens firmware.

Hope you'll find someone who may help you with any further steps. It would probably not be a bad idea to post to the "Deactivate SDM" thread as posters in there will typically have experience using the debug/service menu.

Thanks, that's very helpful, I'll do as you suggest.