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View Poll Results: Select the option that best describes your agreement with the statement
I have a dual SDM and screw drive lens and I want the ability to choose the focus mechanism. 20258.38%
I am planning on buying a SDM/screw drive lens and I want the ability to choose the focus mechanism. 6919.94%
I will not buy a SDM lens until I have the ability to choose the focus mechanism. 7521.68%
Voters: 346. You may not vote on this poll

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09-05-2009, 01:01 PM   #106
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Still trying to encourage everyone to think about this. It only makes the Pentax system stronger and of more value.

Thank you
Russell

09-05-2009, 01:31 PM   #107
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My two pennorth

I have a K20 and a mixture of screw drive and SDM lenses (although I rarely use the screw drives).

Given the body and SDM lenses have both screw drive and SDM capabilities, it seems utterly barking that there is apparently no way to get an SDM lens to use the Screw drive in the event of an SDM failure.

For the want of a couple of lines of software the ship was lost---
09-06-2009, 12:58 PM   #108
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Just a thought. How are the SDM and screw drive systems linked in lens, are they always connected or have some sort of clutch.
If the SDM fails mechanically, cant the screw drive damage lens even more while trying to turn some broken gears for example.
So i believe that failed SDM is not a good reason to implement AF method selection. Broken lens must be repaired and should be left as much intact as possible.
09-06-2009, 01:26 PM   #109
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Would depend on why SDM failed.
Sounds like the majority of cases I've heard are just that SDM kicked the bucket all of a sudden, with no history of trauma to the lens. You'd want the screwmotor AF to take over there, but I'd hazard to guess many who'd experience this would want their SDM motors fixed anyway.

IMO, I don't mind SDM only so long as it's faster and more reliable than screwmotor focus. And IMO, Pentax SDM is neither of these at the moment. Having said that, my 16-50 has been a workhorse and SDM's done the job, which I've been very happy about. Low-light issues notwithstanding, it still is a solidly built and reliable lens. The Sigma 70-200 HSM I recently bought also has decent AF performance, but even still, I found the Tamron 70-200 screwdrive AF hunting less when fine-focusing.

In the end, Pentax should focus more on the SDM technology IMO rather than provide the option of screwdrive AF in these lenses.

09-06-2009, 01:51 PM   #110
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I am surprised by the comments!

I have a 50-135mm with an "unreliable" SDM.
It sometimes works and sometimes doesn't. There is no pattern.
The most frequent problem is that it just refuses to start autofocusing after a lens change.
Of course, the contacts are clean!
Then, all of a sudden it starts to operate!
In my country, servicing this lens is not the easiest thing.

I do not see the reason why some members seem to ignore the need for a button (or menu item) to click and start operating the screw driven focusing!
What harm could that do?

Let us say your HSM stops working in the middle of a shooting session (remember this is a "star" lens, directed to higher end users). Would you call your favorite local Pentax technician to help?

I also doubt, by the way, replacing the motor with a similarly constructed one will make it reliable. The next generation motors may well be alright but I have the present generation lens

So, I repeat, what is wrong in allowing us to switch to the screw driven modality when a need arises?
09-06-2009, 03:59 PM   #111
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Nothing wrong with 'allowing' you to switch, but you'll have to face the reality that Pentax may never actually bring this to fruition.

The technology is evolving, and the engineers would have to realise the problems faced with SDM reliability and durability, so with time you'll probably see a significant improvement in both of these facets across the board.

Bulent, are you switching off the camera between lens changes?
Is your focusing technique consistent?
I ask these as the user issues must always be addressed first before the hardware ones...
09-06-2009, 08:46 PM   #112
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QuoteOriginally posted by ytterbium Quote
Just a thought. How are the SDM and screw drive systems linked in lens, are they always connected or have some sort of clutch.
If the SDM fails mechanically, cant the screw drive damage lens even more while trying to turn some broken gears for example.
So i believe that failed SDM is not a good reason to implement AF method selection. Broken lens must be repaired and should be left as much intact as possible.
Well I don't know how the 2 act independently but you can put an SDM lens on a *istD series camera and it doesn't affect the lens gears. Plus the lenses have a clutch for quick shift.

I had a K20D fail in some odd ways and one thing was the SDM focusing. The lens reverted to screwdrive on it's own. Switching to my other bodies and the lens worked with SDM normally. So I don't think it's an issue going back and forth.

I'd love to figure out how the screwdrive engaged in that body though when the SDM wouldn't work. But it was a body failure and not the lens.
09-07-2009, 02:03 AM   #113
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Maybe im just crazy but couldnt you just cover the SDM contacts on the lens some way and then the camera should see it as a screw drive lens? I thought those 2 contacts were specifically for the SDM. I dont have any SDM lenses so I would not be able to test this, but maybe somebody could try. If it works, hey, quick and easy temporary fix for a problematic SDM motor until they can get it fixed. If it doesnt work you would be out about 2 minutes of time. Anybody willing to try this? Looking at my K20D I dont see any other way the camera would know the lens is SDM unless the contacts were connected to the lens.

09-07-2009, 03:01 AM   #114
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QuoteOriginally posted by MoparFreak69 Quote
Maybe im just crazy but couldnt you just cover the SDM contacts on the lens some way and then the camera should see it as a screw drive lens? I thought those 2 contacts were specifically for the SDM. I dont have any SDM lenses so I would not be able to test this, but maybe somebody could try. If it works, hey, quick and easy temporary fix for a problematic SDM motor until they can get it fixed. If it doesnt work you would be out about 2 minutes of time. Anybody willing to try this? Looking at my K20D I dont see any other way the camera would know the lens is SDM unless the contacts were connected to the lens.
It dosn't work- camera goes nuts
09-07-2009, 03:03 AM   #115
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Ok well it was just a thought. Thanks for trying it so quickly borno!
09-07-2009, 11:15 PM   #116
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Ash,

>Bulent, are you switching off the camera between lens changes?
Yes.

>Is your focusing technique consistent?
I use AF-S most of the time with occasional MF.

>I ask these as the user issues must always be addressed first before the hardware ones...
You're right.
However, I have never experienced a problem when I hit the AF button with a screw drive lens; the thing just moves! With my only SDM lens, it just seems to be pure luck if it moves!
I would have even preferred a total failure than a hit or miss behaviour.
And then, I would be happy to just revert back to screw driven mode!!!
09-08-2009, 06:35 AM   #117
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This is a pretty interesting post.

QuoteQuote:
When I have it on the K-7 and try to auto focus, the lens does not move, and after a few seconds, the camera shuts down, and won't start again. I switch it off, and on again - no LCD, no Monitor. dead.

Took out the battery - put it back in the charger for no more than 10 seconds, then back in the camera - all is well again, battery indicator says "full".

All other lenses work beautifully (DA*16-50, DA 21 ltd, FA 77 ltd, sigma 70-200/2.8, Tamron 28-75, Pentax FA 35, and more...)
All except the 50-135.
But the very same 50-135 works great on my K20D body !!!
Makes me want to go out and try my SDM lens on a K-7 before the warranty expires.

Thank you
Russell
09-11-2009, 10:19 AM   #118
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I've been watching the front page the last few days and haven't seen the number of people viewing the site at anything over 1000, 1000 being generous. That would mean 14% of the viewers would like the option to have the ability to choose the focus drive.

If you look at the number of logged in posters, the number hasn't been over 200 for the times I have looked. That would mean 70% of the actual posters would like the option.

Just food for thought.

Thank you
Russell
09-11-2009, 04:13 PM   #119
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Now I have a good reason for wanting this feature as well. The SDM function of my 16-50 is dead. Awaiting to find out what what my receipt says, but I fear that it is out of warranty and that repairing it will be crazy expensive
09-13-2009, 07:27 PM   #120
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I'm afraid that if you have a SDM lens, you have actually purchased a rather expensive MF lens over the long run. I have already had my DA*50-135 fail, serviced under warranty at the lst minute...but may not be so lucky next time. I would love to have the DA*55 but it is a little too expensive for a MF lens, and that may be exactly what it is in a couple of years.

Pentax can do better, but as long as we keep buying them ...why should they? According to what we hear from Pentax, which is complete silence, there has never been any problem with the DA*16-50. I bet you have heard differently?
Regards!
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