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09-12-2010, 01:45 AM   #16
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QuoteOriginally posted by ogl Quote
DA*16-50/2.8 is NOT SDM only. But dual SDM and screw drive lenses can't work properly if SDM failed. No ability to choose the focus mechanism.
Dual focus lenses can work with cameras without SDM support.

DA17-70 and DA*55 are SDM only. They have no AF at cameras without SDM support.
I am keeping mentioning ring motor cauz this kinda motor could eliminate gears, and be naturally full time manual. I assume pentax didn't have any lens with ring SDM, am I right?

09-12-2010, 01:47 AM   #17
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QuoteOriginally posted by kales Quote
Kevin,
Thank you for posting what you know.
for point 1, maybe pentax is doing some modifications quitely, but what I refer to is some structural change. I once saw a Sigma AF70-200HSM focus video, which impressed me alot. you could feel there's different speed configurations in the Sigma HSM motor, which is a ring type. What I know is DA*16-50's SDM is not ring type, and my assumption is that it still have gears to transfer the torque of the motor. Please correct me if I made mistakes on this.

point 2, as I said, pentax isn't priting WR on the lens, which make me concern it's lower grade than K-5/K-7 body. If so, it will be wasting to mount it to a better WRed body.

point 3, haven't heard it. could anyone confirm
kales,

for point #2:

This comes directly from Pentax's website:
"The PENTAX DA* series of high grade lenses, designed exclusively for PENTAX digital SLR cameras, features the quiet SDM focus system and tightly sealed, weather-resistant and dust-resistant construction to enhance durability for use in rainy or dusty conditions."

So WR is below DA* specifications. WR is lightly sealed against rain and some dust, while DA* is rated against lots of water and dust, tighter seals.

As for the ring motor, I think Pentax wanted to originally keep backwards compatibility with other screw drive lenses.
The DA 17-70 and the DA* 55 i believe are a new mindset at Pentax in that most DSLR owners will end up buying new bodies that will support SDM only lenses. The SDM only lenses are probably ring type and more durable as they do not support screwdrive. I have not heard of a DA* 55 failing nor a DA 17-70 so far.

That's my thought on SDM and WR vs. DA*
09-12-2010, 02:04 AM   #18
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QuoteOriginally posted by theperception2008 Quote
kales,

for point #2:

This comes directly from Pentax's website:
"The PENTAX DA* series of high grade lenses, designed exclusively for PENTAX digital SLR cameras, features the quiet SDM focus system and tightly sealed, weather-resistant and dust-resistant construction to enhance durability for use in rainy or dusty conditions."

So WR is below DA* specifications. WR is lightly sealed against rain and some dust, while DA* is rated against lots of water and dust, tighter seals.

As for the ring motor, I think Pentax wanted to originally keep backwards compatibility with other screw drive lenses.
The DA 17-70 and the DA* 55 i believe are a new mindset at Pentax in that most DSLR owners will end up buying new bodies that will support SDM only lenses. The SDM only lenses are probably ring type and more durable as they do not support screwdrive. I have not heard of a DA* 55 failing nor a DA 17-70 so far.

That's my thought on SDM and WR vs. DA*
I checked the webside.
Now I am convinced that DA*16-50 is WR.

So eliminate screw drive and put a new SDM motor on it please. I am using K100d, but I will buy a body with it together, if the combination really delivers regarding to AF performance ^_^
09-12-2010, 02:32 AM   #19
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Whatever updates will be made on the current DA* lineup, they will be done silently (discussed before - how could Pentax admit shortcomings in past DA* copies?)
We'll just see whether there is any shift of trust with time in these DA*s - and then whether this influences Pentax lens developers in the future...

09-12-2010, 02:47 AM   #20
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QuoteOriginally posted by kales Quote
I am keeping mentioning ring motor cauz this kinda motor could eliminate gears, and be naturally full time manual. I assume pentax didn't have any lens with ring SDM, am I right?
SDM is silent and smooth AF, not speed. It's like micro-USM from Canon.
No ring motors.
09-12-2010, 02:50 AM   #21
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If you put dual SDM and screw drive lenses to the camera with SDM support, SDM will work.
If you put to the camera with screw-drive ONLY, screw-drive will work.

No choice to choose the focus mechanism.
09-12-2010, 03:57 AM   #22
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QuoteOriginally posted by kales Quote
Now I am convinced that DA*16-50 is WR.
Remember also that WR (as a marketing term) came after the DA* had been there already.
09-12-2010, 04:08 AM   #23
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QuoteOriginally posted by ogl Quote
SDM is silent and smooth AF, not speed. It's like micro-USM from Canon.
No ring motors.
But ring motors are silent and smooth AF and at a good speed!

that means technically pentax SDM on DA* is only at canon 50/1.8 or nikon 35/1.8 level. Please give me screw drive and a powerful body motor, and throw this "SDM" away.

We always want more, don't we?
Seems pentax AF algorithms have been improved, why not bring us faster motor drive?

09-12-2010, 04:09 AM   #24
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QuoteOriginally posted by gawan Quote
Remember also that WR (as a marketing term) came after the DA* had been there already.
DA* is more weather resist than WR lenses.
09-12-2010, 04:10 AM   #25
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QuoteOriginally posted by ogl Quote
DA* is more weather resist than WR lenses.
I haven't see any technical spec such as IP level of the lens, so I am not sure.
09-12-2010, 04:12 AM   #26
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QuoteOriginally posted by kales Quote
But ring motors are silent and smooth AF and at a good speed!

that means technically pentax SDM on DA* is only at canon 50/1.8 or nikon 35/1.8 level. Please give me screw drive and a powerful body motor, and throw this "SDM" away.

We always want more, don't we?
Seems pentax AF algorithms have been improved, why not bring us faster motor drive?
Ring-motor is a bit bigger and a bit more expensive. Ask your question to HOYA engineers. I prefer screw-drive. I don't care about noise AT ALL.

But....SDM is the most silent and smooth micro-USM between another brands.

Anyway...maybe we will see SDM II?
09-12-2010, 04:12 AM   #27
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QuoteOriginally posted by Ash Quote
Whatever updates will be made on the current DA* lineup, they will be done silently (discussed before - how could Pentax admit shortcomings in past DA* copies?)
We'll just see whether there is any shift of trust with time in these DA*s - and then whether this influences Pentax lens developers in the future...
They could release a generation 2, with other major improvements, just like Sigma did in their AF70-200/2.8.
09-12-2010, 04:14 AM   #28
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QuoteOriginally posted by ogl Quote
Ring-motor is a bit bigger and a bit more expensive. Ask your question to HOYA engineers. I prefer screw-drive. I don't care about noise AT ALL.

But....SDM is the most silent and smooth micro-USM between another brands.

Anyway...maybe we will see SDM II?

ogl, you are right, screw driver could be the better choice. I don't care the sound too, but I do care about drive speed. It seems screw do not have speed issue.
09-12-2010, 05:51 AM   #29
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QuoteOriginally posted by kales Quote
Now I am convinced that FF is no the only way for Pentax to go, since K-5 is APS and WR and has bette ISO and AF, isn't it a good time to improve the 16-50/2.8 that matches K-5?
Pentax appearently stopped making pro grade (*) lenses for APSC in 2007. Or better say Hoya never made'em. Bodies released thereafter are K20D, K-7, K-5. So, a K-5 alone is no reason to change that.

But they may replace the little plastic gear in the DA*16-50 SDM gear box by a metal one. Or discontinue the lens which I hope they don't. It's a stunning performer (for me).
09-12-2010, 06:07 AM   #30
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QuoteOriginally posted by falconeye Quote
Pentax appearently stopped making pro grade (*) lenses for APSC in 2007. Or better say Hoya never made'em. Bodies released thereafter are K20D, K-7, K-5. So, a K-5 alone is no reason to change that.
You are forgetting the DA* 55/1.4 SDM from 2009. It IS a DA Star lens, albeit the slowest one to date (I guess this was intentional because of its intended purpose: portraiture).
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