I broke my camera and I couldn't be happier!

**Rondec** · 02-23-2010, 06:09 AM

Originally posted by pingflood

So if SDM is less accurate and slower than in-body motor, what the heck's the point? Seems like it'd just add cost to each lens and not do any good.

SDM to me is equivalent to screw drive, just quieter. I certainly don't think it is less accurate and don't see it as much different in speed. I know my DA * lenses are slower focusing than my primes, but they also have different focus throws and a lot more glass to move. All in all, they are equivalent from that stand point in my book.

The issue to me with SDM is primarily reliability. I know some people really need fast focusing lenses, but I don't particularly, but I do want a thousand dollar lens to last for many years.

JeffJS · 02-23-2010, 10:34 AM

Originally posted by Peter Zack

Well I'm sad to report that the SD focus is not much better. I detail it here

Therr's just something about this design that doesn't work nearly as well. Btw I tried to replicate the 'accident" on the K10D but I can't yet.

Is it possible you had the AF button or the shutter button pressed while removing the lens (in your original post)? Seems to me, that if the SDM isn't trying to operate, there wouldn't be a load on the circuit and therefore not drawing any current. Hence, nothing to short out. I don't have evidence of it and it's guess work only but I would think that Pentax would have idiot proofed that circuit. They couldn't have thought no one would ever change lenses without first turning off the camera.. Could they???

PentaxPoke · 02-23-2010, 12:35 PM

Originally posted by Rondec

SDM to me is equivalent to screw drive, just quieter. I certainly don't think it is less accurate and don't see it as much different in speed. I know my DA * lenses are slower focusing than my primes, but they also have different focus throws and a lot more glass to move. All in all, they are equivalent from that stand point in my book.

The issue to me with SDM is primarily reliability. I know some people really need fast focusing lenses, but I don't particularly, but I do want a thousand dollar lens to last for many years.

I agree about the last part, but I do believe SDM is slower, particularly on the K-7. Unfortunately we will never know exactly until Pentax lets us use the screw drive in the DA* lenses.

The reason I think it is slower is that when I had the 16-50 on my k10d, and then I updated the firmware to the higher level (which deactivated SD) the SDM focus was not faster. It may have seemed a bit slower, but I cant be sure. The k20d, and especially the k-7 increased the speed of the SD motor (you can even hear the difference in the k-7.) That increased the rotational rate of the focus ring. SDM being driven by the lens motor as opposed to the body motor did not change. When I had DA* lenses, they did not focus any faster between the k10d, k20d, or k-7.

There is my rational for why the SDM is not faster than SD.

But I still want to know where Peter's thread went.

There was a lot of useful information there!

Aha, it is back now (with a modified title for those of you that remember the first title

) https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/86274-superson...a*16-50mm.html

**barondla** · 02-23-2010, 12:51 PM

Has anyone considered asking Eric, the great Pentax repair man, if he knows how the camera was broken. Maybe some one here is a good customer of his and knows him well?

Seems like the lens must send info to camera if its SDM or not. The body must be scrambling the info so it reverts to screw drive. Can the body still decipher what lens and focal length in the exif?

thanks
barondla (still no SDM lenses)

Check out POINT & SHOOT CONTEST #27 in compact camera forum. Enter #28. Any brand camera. Enter now!

GoremanX · 03-01-2010, 06:35 PM

I think it's important to point out that shorting out those contacts also means that any Sigma HSM lenses will no longer auto-focus at all. They don't have screw-drive. Also, any new successor to SDM will inevitably use those contacts for power, and shorting them out would prevent those future, mythical lenses from auto-focusing too.

I was almost tempted to try shorting out my K-7's power contacts on purpose until I realized this.

And as many people have mentioned, taping over the contacts doesn't work. It just makes the camera blink AF/MF furiously at you in anger. You can almost feel the seething rage coming out of the camera...

02-23-2010, 12:35 PM	#33
PentaxPoke Veteran Member Join Date: Jan 2008 Location: Oklahoma Posts: 1,411	Originally posted by Rondec SDM to me is equivalent to screw drive, just quieter. I certainly don't think it is less accurate and don't see it as much different in speed. I know my DA * lenses are slower focusing than my primes, but they also have different focus throws and a lot more glass to move. All in all, they are equivalent from that stand point in my book. The issue to me with SDM is primarily reliability. I know some people really need fast focusing lenses, but I don't particularly, but I do want a thousand dollar lens to last for many years. I agree about the last part, but I do believe SDM is slower, particularly on the K-7. Unfortunately we will never know exactly until Pentax lets us use the screw drive in the DA* lenses. The reason I think it is slower is that when I had the 16-50 on my k10d, and then I updated the firmware to the higher level (which deactivated SD) the SDM focus was not faster. It may have seemed a bit slower, but I cant be sure. The k20d, and especially the k-7 increased the speed of the SD motor (you can even hear the difference in the k-7.) That increased the rotational rate of the focus ring. SDM being driven by the lens motor as opposed to the body motor did not change. When I had DA* lenses, they did not focus any faster between the k10d, k20d, or k-7. There is my rational for why the SDM is not faster than SD. But I still want to know where Peter's thread went. There was a lot of useful information there! Aha, it is back now (with a modified title for those of you that remember the first title ) https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/86274-superson...a16-50mm.html Last edited by PentaxPoke; 02-25-2010 at 12:05 PM.*

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02-23-2010, 06:09 AM	#31
Rondec Loyal Site Supporter Join Date: Mar 2009 Location: Gladys, Virginia Photos: Gallery Posts: 27,653	Originally posted by pingflood So if SDM is less accurate and slower than in-body motor, what the heck's the point? Seems like it'd just add cost to each lens and not do any good. SDM to me is equivalent to screw drive, just quieter. I certainly don't think it is less accurate and don't see it as much different in speed. I know my DA * lenses are slower focusing than my primes, but they also have different focus throws and a lot more glass to move. All in all, they are equivalent from that stand point in my book. The issue to me with SDM is primarily reliability. I know some people really need fast focusing lenses, but I don't particularly, but I do want a thousand dollar lens to last for many years.

02-23-2010, 10:34 AM	#32
JeffJS Inactive Account Join Date: Aug 2008 Location: Michigan, USA Photos: Gallery \| Albums Posts: 7,484	Originally posted by Peter Zack Well I'm sad to report that the SD focus is not much better. I detail it here Therr's just something about this design that doesn't work nearly as well. Btw I tried to replicate the 'accident" on the K10D but I can't yet. Is it possible you had the AF button or the shutter button pressed while removing the lens (in your original post)? Seems to me, that if the SDM isn't trying to operate, there wouldn't be a load on the circuit and therefore not drawing any current. Hence, nothing to short out. I don't have evidence of it and it's guess work only but I would think that Pentax would have idiot proofed that circuit. They couldn't have thought no one would ever change lenses without first turning off the camera.. Could they???

02-23-2010, 12:51 PM	#34
barondla Site Supporter Join Date: Sep 2006 Location: midwest, United States Photos: Gallery \| Albums Posts: 5,714	Has anyone considered asking Eric, the great Pentax repair man, if he knows how the camera was broken. Maybe some one here is a good customer of his and knows him well? Seems like the lens must send info to camera if its SDM or not. The body must be scrambling the info so it reverts to screw drive. Can the body still decipher what lens and focal length in the exif? thanks barondla (still no SDM lenses) Check out POINT & SHOOT CONTEST #27 in compact camera forum. Enter #28. Any brand camera. Enter now!

03-01-2010, 06:35 PM	#35
GoremanX Veteran Member Join Date: Dec 2009 Location: Georgia, VT Photos: Albums Posts: 1,657	I think it's important to point out that shorting out those contacts also means that any Sigma HSM lenses will no longer auto-focus at all. They don't have screw-drive. Also, any new successor to SDM will inevitably use those contacts for power, and shorting them out would prevent those future, mythical lenses from auto-focusing too. I was almost tempted to try shorting out my K-7's power contacts on purpose until I realized this. And as many people have mentioned, taping over the contacts doesn't work. It just makes the camera blink AF/MF furiously at you in anger. You can almost feel the seething rage coming out of the camera...