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07-18-2012, 01:30 PM   #91
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QuoteOriginally posted by Docrwm Quote
Honest question so don't just shoot me. Was the last silent motor lens released the 18-135? If so, perhaps the DC motor, which has been trouble free based on the database responses, was Pentax's answer?
Pentax has reported to use the DC only in lower-end lenses, the SDM will be used in the DA* lenses.
Most likely reason is that the SDM are more powerful compared to DC.

07-18-2012, 01:33 PM   #92
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QuoteOriginally posted by Anvh Quote
Anders kan ik ook gewoon in mijn eigen taal gaan typen dan mag jij het lekker gaan vertalen, ben benieuwt hoe dat je bevalt.
That won't help: Holland is SW Michigan, not SE.
07-18-2012, 01:40 PM   #93
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QuoteOriginally posted by Anvh Quote
Funny how every here has an opinion about me, I would have several camera brands by now in all shape and sizes
Anyway, where did i said there wasn't a problem?

I thought you means less people use a 300mm lens compared to how many use the 60-250mm, sorry i read your comment wrong but that has nothing to do how smart or stupid i'm so don't talk me down.
Anders kan ik ook gewoon in mijn eigen taal gaan typen dan mag jij het lekker gaan vertalen, ben benieuwt hoe dat je bevalt.

Back to topic, i would love to see where you base that data on that the 300 is used less then the 60-250, i've never seen any figures about that.
Reading comprehension has nothing to do with how smart or dumb you are.

Type in whatever language you wish. I can ignore you in any of them. On the other hand, you might make more sense in Dutch than English, so go for it.

Last edited by Tom S.; 07-18-2012 at 01:48 PM.
07-18-2012, 02:01 PM   #94
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QuoteOriginally posted by lytrytyr Quote
But at least we can use the collective wisdom of this forum to try to gather some impressions.
One of those impressions is that disuse worsens the problem, and not just through allowing electrical discharge.
It may be some grease hardening, or it may be some other effect.
I've taken a 16-50 apart to free up the motor, and I doubt it's anything to do with a lubricant: quite the converse, as the SDM, like any piezo motor, uses friction as the means of transferring force and motion to the rotor, so a lubricant could only be needed for bearings, and at that size and duty I'd suspect they're the "dry" type. My best guess, without taking a motor apart, is that the gripping piezo elements are the culprits, but without hard evidence it's only a guess. Other piezo motors doing similar duty don't have this issue, so the only thing clear is that it's either a manufacturing defect that the motor supplier won't admit to, or a poor design selection by Pentax.

We also don't really know what sort of drive the DC motor is, as far as I can gather. I know what DC means in the general engineering world, but whether that applies here is hard to say. Manufacturers have a habit of re-badging technology to assuage bad impressions from previous failures, instead of admitting to fault.

07-18-2012, 02:05 PM   #95
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QuoteOriginally posted by RobA_Oz Quote
I've taken a 16-50 apart to free up the motor, and I doubt it's anything to do with a lubricant: quite the converse, as the SDM, like any piezo motor, uses friction as the means of transferring force and motion to the rotor, so a lubricant could only be needed for bearings, and at that size and duty I'd suspect they're the "dry" type. My best guess, without taking a motor apart, is that the gripping piezo elements are the culprits, but without hard evidence it's only a guess. Other piezo motors doing similar duty don't have this issue, so the only thing clear is that it's either a manufacturing defect that the motor supplier won't admit to, or a poor design selection by Pentax.

We also don't really know what sort of drive the DC motor is, as far as I can gather. I know what DC means in the general engineering world, but whether that applies here is hard to say. Manufacturers have a habit of re-badging technology to assuage bad impressions from previous failures, instead of admitting to fault.
The only thing I have seen from Pentax that differentiates the SDM from the DC designs said two things - the DC is weaker than the SDM motor and the placement within the lens is different.
07-18-2012, 07:21 PM   #96
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QuoteOriginally posted by RobA_Oz Quote
I've taken a 16-50 apart to free up the motor, and I doubt it's anything to do with a lubricant: quite the converse, as the SDM, like any piezo motor, uses friction as the means of transferring force and motion to the rotor, so a lubricant could only be needed for bearings, and at that size and duty I'd suspect they're the "dry" type.
I was thinking more along the lines of grease hardening on the helicoid,
increasing the load beyond what the weak motor could handle.
07-20-2012, 06:43 AM   #97
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QuoteOriginally posted by lytrytyr Quote
I was thinking more along the lines of grease hardening on the helicoid,
increasing the load beyond what the weak motor could handle.
Ah, well, that's a different matter, but I didn't take mine apart that far to be able to say one way or another. You'd think at least one Pentax technician would have discovered that by now, though.
07-20-2012, 07:01 AM   #98
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QuoteOriginally posted by RobA_Oz Quote
You'd think at least one Pentax technician would have discovered that by now, though.
There may not be a choice, if lighter grease will not stay in place.

Some reviewers have complained about stiff manual focus on recent Zeiss lenses.
They may have been finding a similar hardening effect.

07-20-2012, 01:26 PM   #99
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QuoteOriginally posted by lytrytyr Quote
That won't help: Holland is SW Michigan, not SE.
haha that's precisely the point
If you look around the northern east coast around New York for example you will see a lot of Dutch words and names around for places, quite funny actually.

http://en.wikipedia.org/wiki/Toponymy_of_New_Netherland

Last edited by Anvh; 07-20-2012 at 02:16 PM.
07-20-2012, 01:51 PM   #100
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QuoteOriginally posted by Tom S. Quote
Reading comprehension has nothing to do with how smart or dumb you are.

Type in whatever language you wish. I can ignore you in any of them. On the other hand, you might make more sense in Dutch than English, so go for it.
Speciaal voor jou dan want we hebben het al lang niet meer over de SDM, want waar gaat het nu over? Lijkt meer op een spel van jou om mij af te zeiken.

Veel geluk met vertalen, één tip gebruik geen vertaal machine die komt uit geen één van mijn zinnen namelijk
07-20-2012, 01:56 PM   #101
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QuoteOriginally posted by RobA_Oz Quote
We also don't really know what sort of drive the DC motor is, as far as I can gather. I know what DC means in the general engineering world, but whether that applies here is hard to say. Manufacturers have a habit of re-badging technology to assuage bad impressions from previous failures, instead of admitting to fault.
As far as i know it's a brushless DC motor but i could be wrong... either way it's most likely DC since the PZ contacts are DC not AC and i doubt they will trun DC to AC inside the lens.
(sorry for the acronyms)

About lens motors, have you seen this one from Pentax?
http://www.freepatentsonline.com/20090323208.pdf

Last edited by Anvh; 07-20-2012 at 02:09 PM.
07-20-2012, 01:56 PM   #102
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QuoteOriginally posted by Anvh Quote
Speciaal voor jou dan want we hebben het al lang niet meer over de SDM, want waar gaat het nu over? Lijkt meer op een spel van jou om mij af te zeiken.

Veel geluk met vertalen, één tip gebruik geen vertaal machine die komt uit geen één van mijn zinnen namelijk
Nope I was wrong, you make just as little sense in Dutch as you do in English, so I guess it's ignore.
07-20-2012, 03:17 PM   #103
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QuoteOriginally posted by Anvh Quote
If you look around the northern east coast around New York for example you will see a lot of Dutch words and names around for places, quite funny actually.
My favorite is Fishkill, which has taken on a whole new meaning now the creek is polluted.
07-21-2012, 06:16 AM   #104
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QuoteOriginally posted by Tom S. Quote
Nope I was wrong, you make just as little sense in Dutch as you do in English, so I guess it's ignore.
What childish putting people on ignore, it actually only makes it easier for me to say things about you.
07-21-2012, 06:20 AM   #105
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QuoteOriginally posted by lytrytyr Quote
My favorite is Fishkill, which has taken on a whole new meaning now the creek is polluted.
Nice one
Too bad of the fish though and the water
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