[Bob from Aus]

I have spent some time trying to get a good shots from my TC 1.4 and 60-250 combo. With my 100mm wr macro I wasn't having any issues. I have now adjusted my AF by +10 and it seems to have done the trick. I find it difficult to believe I get a back focus issue by placing a TC on it.

[rawr]

I have now adjusted my AF by +10 and it seems to have done the trick. I find it difficult to believe I get a back focus issue by placing a TC on it.

As others have suggested, it's simply possible that AF accuracy suffers from the lower contrast of a darker lens. Your experience using flash with the 100 Macro perhaps bears this out - more light, better AF.

I can't remember if the new TC also switches the metering to centre-weighted, or preserves all the normal metering modes in operation, including matrix. If it is the case that the TC forces the camera to go into centre-weighted metering by default (or worse, spot), this may impact the AF performance, since metering and AF are to a degree computed together, especially on on the K-3.

Another thought is that with the TC in use, fewer AF points may be being used than normal. Learning from my reading of how some Canon bodies work, with certain Canon lens models and TCs for example (fast lenses to slow lenses, basically, as detected by the camera) cameras like the 1Dx and 5D3 will start making use of fewer and fewer AF points, according to the 'lightness' profile of the lens. Ultimately the fast 2.8 cross-type sensors in the middle of the AF frame end up being the only ones that really get used.

Perhaps the K-3 and the K-5II's AF system works the same. Even though the K-3 and K-5II will AF down to -3EV, and both have f2.8 cross-type AF sensors at the centre of the frame (1 on the K-5II, 3 on the K-3), maybe the AF on the K-3 with the 60-250 and a TC is only using something like 9 AF points clustered around the centre, or perhaps just the f2.8 luminance flux AF points in the direct centre of the frame. That sort of behaviour might impact the AF adjustment required for the lens with or without the TC mounted , depending on how the camera is shot and tested.

[derekkite]

It meters and focuses like a normal lens. I'd suggest that if you have to adjust it that much it is out of alignment and should be exchanged. Mine on the DA*300 is straight through with my copy that is right on, and +5 with my copy that requires +5.

My only beef is that is swallows light. Already in August I'm taking it off unless it is a very bright day.

[Bob from Aus]

It meters and focuses like a normal lens. I'd suggest that if you have to adjust it that much it is out of alignment and should be exchanged. Mine on the DA*300 is straight through with my copy that is right on, and +5 with my copy that requires +5.

Thanks for your suggestion. I will take it in next week to the importer and distributer (CR Kennedy) and provide an update of what they say and or do.

[Bob from Aus]

Final Report _ I am happy now

CR Kennedy ended up taking the TC, K3 and the 60-250 zoom. They adjusted the focus on the K3 and the zoom and didn't touch the the TC. The combo works brilliantly (mouth watering to be exact) and now I have a viable alternative to taking the 500mm everywhere. There was no charge although I've had the 60-250 for quite a while.

[crewl1]

Congrats, nice to hear a good ending to your story.

[Bob from Aus]

I've had the TC for 11 months and was still very unhappy with the performance. I gave it one last go and compared images using my 60-250 with and without the TC looking at detail in the black feathers of swans.

I phoned CR Kennedy and they said I could come down the next day and compare mine with one fresh out of the box. It was a grubby overcast day so not a good one for comparing lens setups. The new TC seemed better. They were happy to swap the TCs.

I must place a caveat on this comment as its winter here and I might be having a backfocus issue I can't pick up until I have good light. Getting back to the black swan, there is a lot of improvement but not as good as the 60-250 on its own. I would say that there are plenty of pentax product that I've used that have a much lower pentax forum rating that the TC, but optically perform much better.

[fwcetus]

It meters and focuses like a normal lens. I'd suggest that if you have to adjust it that much it is out of alignment and should be exchanged. Mine on the DA*300 is straight through with my copy that is right on, and +5 with my copy that requires +5.

My new DA 1.4X TC works basically the same way that derekkite reported with the two lenses I've used the TC with. The focus adjustment for the FA* 80-200/2.8 works out to +4, with or without the TC, while it's ±0 for the F* 300/4.5, with or without the TC.

[I haven't had a chance to use the TC too much just yet, but the center sharpness seems about the same as with the Kenko 1.5X AF TC (I don't know how the corners compare quite yet, but I'm hoping that Pentax TC might show at least a slight improvement.) Two things that are really nice, though, are seeing my K-3 reporting the correct effective aperture and effective FL with the TC mounted.]

[raider]

Final Report _ I am happy now

CR Kennedy ended up taking the TC, K3 and the 60-250 zoom. They adjusted the focus on the K3 and the zoom and didn't touch the the TC. The combo works brilliantly (mouth watering to be exact) and now I have a viable alternative to taking the 500mm everywhere. There was no charge although I've had the 60-250 for quite a while.

Hi Bob, I am following your thread with keenest interest as I have just landed a DA*300. I am planning to get a TC but will want to wait a little.

When u say CRK took your TC, K3 and 60-250 for a calibration....obviously your TC is still in warranty...do they charge a fee for doing that for u (I am making the assumption that the K3 and DA60-250 are no longer in warranty)? What exactly did they adjust on the K3 do u know?

Thanks

[Bob from Aus]

When u say CRK took your TC, K3 and 60-250 for a calibration....obviously your TC is still in warranty...do they charge a fee for doing that for u (I am making the assumption that the K3 and DA60-250 are no longer in warranty)? What exactly did they adjust on the K3 do u know

hi Raider

CR Kennedy didn't charge for anything

CR Kennedy wanted to get TC firmware from Japan to adjust the original TC. Because it didn't arrive, they took my K3, 60-250 and TC and adjusted everything so that it was able to focus properly. Up until that stage I ran out of back focus adjustment in my menu. After that the focus was spot on, but I lost all the qualities that make the 60-250 a fabulous lens. Maybe my copy of the 60-250 is exception, but it provides mouth watering results.

Everyone other than I have raved about this TC. From everyone else comments it would be suggested that the 300 plus the 1.4 TC should be a great combination. I think on a zoom with many more pieces of glass it may be expecting to much.

I'm happy that I had it exchanged. I will try it out more often.

Over forty years I've had an excellent run with CR Kennedy. I was very happy that Ricoh didn't decide to take over the distribution.

[raider]

Thanks Bob for that.

hi Raider

CR Kennedy didn't charge for anything

CR Kennedy wanted to get TC firmware from Japan to adjust the original TC. Because it didn't arrive, they took my K3, 60-250 and TC and adjusted everything so that it was able to focus properly. Up until that stage I ran out of back focus adjustment in my menu. After that the focus was spot on, but I lost all the qualities that make the 60-250 a fabulous lens. Maybe my copy of the 60-250 is exception, but it provides mouth watering results.

Everyone other than I have raved about this TC. From everyone else comments it would be suggested that the 300 plus the 1.4 TC should be a great combination. I think on a zoom with many more pieces of glass it may be expecting to much.

I'm happy that I had it exchanged. I will try it out more often.

Over forty years I've had an excellent run with CR Kennedy. I was very happy that Ricoh didn't decide to take over the distribution.