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01-13-2012, 05:04 AM   #31
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maybe you should try the solution i posted already

01-13-2012, 09:09 AM   #32
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Did that cost you anything, beyond shipping, or did Sigma re-chip it for free?

On a (possibly) related note, I have a Tamron 2x Pz-AF BBAR MC7 teleconverter. On my K10D, with a Tamron 70-300 F4-5.6, it would sometimes work (at F4 in good light) allowing the camera to autofocus, but most often not. I understand why as I had faster lenses that it worked with.

That said, I expected the teleconverter to be fully usable on my K5 with the Tamron 70-200 F2.8. Unfortunately, I have found only one circumstance in which it comes close to working - in fairly low light with a very near subject. Under every other combination of lighting and distance the autofocus just shudders, slowly twitching itself fully one way, then stopping.

Is there any chance you have this, or a similar, teleconverter and experienced the same thing? If so, did Tamron re-chipping the lens affect this behavior?

The K5, this teleconverter and my fast Sigma lens combination behaves similarly. This combination works well with my K10D though, so I know that the something that is different is with the K5. I just don't know if the only fix will come from pentax, or from the lens makers.
01-21-2012, 02:42 AM   #33
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QuoteOriginally posted by Mehlsack Quote
How should QC be able to know what tolerances your Lens at home will have :S and how to compensate this?
Two options:
1) Either offer +/-20 steps to cover the whole intoleerances that are tolerated by Pentax.
2) Keep the tolrenaces tight enought that the combination of all parts still works.

Third option:
Accept a certain number of misaligned lenses/camera and assume that 90% of the people with such gear won' notice and only 1% of these people will send in the camera for repair. Simple calculation - Ford used to become infamous for this...
01-21-2012, 02:48 AM   #34
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QuoteOriginally posted by zapp Quote
I feel like I am doing the job of Pentax quality control using the AF fine adjust function... It is a pain in the butt taking 21 shots shots for checking the optimum adjustment position, multiply by the number of lenses and settings you are testing. Please add a 21 shots fine adjustment function covering all steps from -10 to +10 assuming that the camera is fixed on a tripod. Pressing buttons repetetavily is tedious and may result in additional errors.

I like using the Hi position of the motor drive assuming that sometimes the second or third frame will produce less camera shake or cover a certain moment a little better than the first shot. This often works OK, but I end up with 5-8 frames unless I start thinking that I need to take the finger off the shutter relesae button before I even start clicking the button - this produces shake again. Well, let me limit the number of frames taken in Hi mode. In most cases image 5-999 will not show better results than images 1-3 or cover any other important moment in focus. Just as an additional option.

... anything else that may included in a firmware update ...? I feel that I need to spend so much time on fine tuning the K5, please do not introduce a new interesting camera within the next 2-3 years.
I keep adding simple things...

2 second MLU delay is useless on aluminum tripods, add 5 sec delay MLU
I want to copy my camera setting to the SD card - after it returned from service, all default were back in place - very funny.

I am still talking about BASICS - Canon offers different MLU offsets for over a decade, Nikon allows saving of personalized setings for quite a long time. I have enough reason not to buy a Canon/Nikon at the moment, I hope Pentax will keep it that way.

01-21-2012, 03:13 AM   #35
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QuoteOriginally posted by Frogfish Quote
I think you misunderstand how this 'misalignment' as you call it comes about (and no the postion may not be easily 'visibly off' as that would depend on perspective as well as F-stop).

There was a very interesting article written by one of the lens rental companies ( I think it was Lensrentals .. but I can't find the specific article now) in the USA on how a client would hire a lens and then send it back saying the lens had a problem front focusing .... but the next client they would send the lens out to (after checking and finding no issues with the lens) would find it absolutely perfect and the next client would say it back focuses ! This by the way applies to Canon, Nikon and every other manufacturer who's lenses they stock(ed).

The explanation is in the 'AF tolerance range' permitted in manufacture of both the lenses and cameras. A camera would pass the QC if it fell within a hypothetical 0 to +6 or 0 to -6 tolerance, a lens would pass if falling within the same tolerance (this is across all manufacturers). It is then immediately obvious what this means : a +6 camera and a +6 lens would take it outside the range of AF in-camera adjustment and the owner blaming either the lens or the camera. A +6 camera and -6 lens would give absolutely perfect focus .. and the owner believing he had a perfect example of that lens ! Sell that lens to someone else with a -6 camera and a dispute erupts on the 'damaged' lens being sold !

The vast majority of cameras/lens combinations though could be easily adjusted in-camera or slight mis-focus not an issue as under normal circumstances it wouldn't be noticed (e.g. camera +5 and lens -3 = +2 as normally easily covered by the DoF - irrespective of where the plane of focus lies.)
Your explanation is way too simple. It is not a God given fact that Pentax has to work with the tolerances you mention. The tolerances that you mention are "permitted" by Pentax. They should either keep tolerances down or let me adjust for their offsets. Keeping them down will be expensive. Provide me with more correction steps and I am OK.

You may also want to do some reading on how the plane of best focus changes with aperture and distance. All Noctilux users and Zeiss 1.4/85 users should know about the implications.

If you consider DOF as a range of sharpness and unssharpness areas around the plane of best focus, the effect can not be covered by DOF. The whole discussion on bokeh and lens rendering becomes rather pointless in this case.
01-21-2012, 05:12 AM   #36
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The first camera that seems to have accurate enough AF to not need micro adjust is the Canon D60. Every DSLR before it either has micro adjust or it has a user base who is up in arms about not having it.
Here's a suggestion: Learn to live within the limitations of your equipment. You'll be a lot happier and the internet will be a quieter place with less useless drivel.
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