OK, here is what I encourage everyone to do:
In addition to the current petition to get a firmware update to permit the use of screwdrive on SDM lenses (on those that have it available), which I do think is a good idea, I would like to see pressure mounted on Pentax corp. to focus on their SDM development to create a generation of robust, faster and more reliable AF on their DA* lenses. If we're paying a lot more for them, they ought to live up to their professional-grade status and perform as such for the long term.
My statement sent to them a few weeks ago:
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I would like to express an area of concern with the current Pentax DA* series lenses that is shared amongst many members of PentaxForums.com. The SDM technology has been an excellent advancement in the modern era of autofocus lenses, however to date there have been numerous personal reports of SDM failures, particularly with the popular DA* 16-50mm and 50-135 lenses.
I have had no reservations on purchasing these lenses myself earlier this year, however the current sentiment on the frequency of SDM failures does send the message that SDM failure is inevitable, and is at least a psychological deterrent from purchasing further SDM lenses. This is unfortunate given the high quality of the DA* lens range and the quality of autofocus provided by rival USM/HSM lenses. Although not an authoritative source of failure rate data, these are the threads illustrating some of the impact of SDM failure on Pentax users:
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/75316-sdm-da-f...er-2009-a.html https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/73555-sdm-lens-failures.html https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/81128-more-sdm-problems.html https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/69791-sdm-lens-safe-buy.html https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/67114-another-16-50-dead.html https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/48853-da-16-50...oom-focus.html https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/22187-da-16-50...king-k10d.html
Further to the apparent SDM failure rate, one other area of improvement that I and others in the forum would like to suggest is in autofocus speed and accuracy. There are times, not infrequently, that the lenses lock focus incorrectly, and since it may be difficult to discern this in the viewfinder, leads to out of focus images taken.
The SDM AF speed is also not improved, even at times slower due to hunting, compared to many screwdriven AF lenses of similar focal ranges. Below are a couple of threads that support this concern:
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/45227-you-satisfied-sdm.html https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/21436-af-wont-...asionally.html
Overall, it seems the most pressing SDM issue is its apparent high failure rate. The virtue of having autofocus is completely lost when this motor fails. Some members suggest permitting the screw-drive focus mechanism to take over when SDM fails (see
https://www.pentaxforums.com/forums/pentax-dslr-discussion/60184-screw-drive-...dm-lenses.html), however I believe this will not curb consumer concern about SDM, which stops many of them from making SDM lens purchases. I also suggest that a quality robust SDM is more worthwhile than the ability to switch from SDM to screw-drive AF, which I believe is only an interim measure to maintain the usefulness of these pro-grade lenses.
The one significant effort that Pentax can do right now to improve customer confidence in SDM lenses, and therefore boost profits from DA* lenses, is to provide an extended warranty.
If these concerns can be acknowledged and worked upon by Pentax, I would easily vouch that a more trusting sentiment on the DA* lenses would ensue, and as a result a much higher purchase rate and investment into Pentax photographic equipment.
Thank you.