Pentax should design only SDM lenses in future

Started May 9, 2010 | Discussions thread
grahamdyke Regular Member • Posts: 152
Re: Are you going to pay for out of warranty SDM problems?

Roland Mabo wrote:

The "SDM issues" has been related to the dual AF lenses, not single AF lenses with only SDM.

Well my 17-70 SDM was just over a year old when its SDM broke. This issue is NOTHING to do with the lens having a dual drive system.

Its just that the Pentax SDM drive is very weak and certainly no faster than a screw drive lens on a K20D/K7. All you gain is a tiny bit of quiet. Its not worth the candle.

In addition the Pentax QC is hopeless, as is the servicing, at least in the UK. There is no real Pentax service center in the UK any more, just a collection point at Johnsons Photopia Ltd. We now only have a sales office. All repairs are forwarded to the Pentax service center in Hambourg Germany.

I have owned 3 Pentax lenses to date, a mixture of SDM and screw drive:

12-24 f/4 - Sold it shortly after buying it as it would simply not focus in any sort of lowish contrast scene, where all my other lenses would lock focus fine. Replaced with a Sigma 10-20 f/4-5.6 Fabo.

17-70 f/4 - Zoom mechanism would catch at 17mm, sent for repair, new parts fitted, came back 6 weeks later! with the same fault. Then the SDM broke a couple of months later out of warranty. The lens went in the skip. Replaced with a Sigma 17-70 f/2.8-4 HSM OS Fabo.

55-300 f/4-5.8 - Decentering issues causing right side softness, sent for repair, came back 6 weeks later! At least the repair was good. Sold it anyway as I found the zoom mechanism somewhat less than smooth, making fine adfustments impossible. Replaced with a Sigma 70-200 f/2.8 HSM II, this was not so Fabo, found it too soft at 200mm, Front focused big time and no go with either my Tamron-F 1.4x TC, or Promaster 1.7x TC, so sold it. Replaced with Tamron 70-200 f/2.8 and this realy is Fabo and works a dream with both TC's.

So no more Pentax lenses for me, not untill they improve their QC and implement a more robust SDM drive system. I'm sure as hell not gona spend £1000 on a lens only to have to spend another £300-600 after 14 months getting it repaired.

I have also owned the Tamron 18-250 and although the IQ of this little lens is not gona set the world alight, it was a real vacation workhorse. Eventually sold it after 2 years hard work to get better IQ.

I still have, what I regard as my best lens, the Tamron 90mm 1:1 macro. Now this is the top of the tree when it comes to IQ, a great lens and takes both the Tamron and Promaster TC's without complaint, giving great flexability and options.

My advice would be: If you own a Pentax SDM lens make sure you sell it well before the warranty runs out, unless you feel realy lucky.

My advice woul also be: Don't buy a secondhand Pentax SDM lens under any circumstances.

I think the industry as a whole needs to shape up with respect to QC.
Graham Dyke

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