Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-20-2010, 04:27 PM   #136
Senior Member




Join Date: Jul 2008
Location: Arizona
Posts: 283
DC Motor...

..as already discussed may be Pentax's answer to a simple direct electric drive focusing motor. It does not operate at ultrasonic frequencies but from the patent appears to use pulsed direct current (DC). The design drives the focus ring by magnetic coupling and is mechanically very simple. The electronic drive circuitry is also lower voltage and simpler than those used for ultrasonic motors.

My guess would be that the poor reliability of SDM has given Pentax an incentive to go with a new design.

Mike

09-20-2010, 04:52 PM   #137
Senior Member
HeavyD's Avatar

Join Date: May 2009
Location: New York
Posts: 155
Photography Review has the price being $529. For that price I could get a Sigma 18-250mm OS HSM or a nice used DA* 50-135mm. $529 is to much, the Sigma 18-125mm HSM is only $300.

Pentax smc DA 18-135mm f/3.5-5.6 ED AL [IF] DC WR Zoom Lens | Camera News & Reviews
09-20-2010, 05:26 PM   #138
New Member




Join Date: Feb 2010
Location: United States
Posts: 24
QuoteOriginally posted by HeavyD Quote
Photography Review has the price being $529. For that price I could get a Sigma 18-250mm OS HSM or a nice used DA* 50-135mm. $529 is to much, the Sigma 18-125mm HSM is only $300.
Pentax smc DA 18-135mm f/3.5-5.6 ED AL [IF] DC WR Zoom Lens | Camera News & Reviews
Considering that lenses such as the DA 40mm Limited retails for $500, and sells for $330 from B&H, it won't take long for this lens to be selling for around the $375 neighborhood. I think that is a pretty fair price for the added benefits of being more compact, weather resistent, and not a Sigma.
09-20-2010, 06:29 PM   #139
Pentaxian
Clarkey's Avatar

Join Date: Jan 2008
Location: Brampton, ON, Canada
Photos: Gallery
Posts: 1,623
QuoteOriginally posted by HeavyD Quote
Photography Review has the price being $529. For that price I could get a Sigma 18-250mm OS HSM or a nice used DA* 50-135mm. $529 is to much, the Sigma 18-125mm HSM is only $300.

Pentax smc DA 18-135mm f/3.5-5.6 ED AL [IF] DC WR Zoom Lens | Camera News & Reviews
Weather sealing is a unique feature on this zoom range, to be honest I was expecting around $600 USD. Point taken though, I think Sigma has really upped their ante with this years releases/value.

QuoteOriginally posted by Jend Quote
Considering that lenses such as the DA 40mm Limited retails for $500, and sells for $330 from B&H, it won't take long for this lens to be selling for around the $375 neighborhood. I think that is a pretty fair price for the added benefits of being more compact, weather resistent, and not a Sigma.
Agreed, I've noted all of the street prices have been slowly creeping back down after the ridiculous list price increases at the beginning of 2009. Still, I don't think we are going to see (using your example) the 40mm at ~$230 US again. The rising yen has taken care of that (even though the lenses are now made in Vietnam).


Last edited by Clarkey; 09-20-2010 at 06:29 PM. Reason: putting things in the right place.....
09-20-2010, 06:34 PM   #140
Pentaxian
Arpe's Avatar

Join Date: Sep 2006
Location: New Zealand
Photos: Gallery | Albums
Posts: 4,331
So nobody knows if DC is faster than SDM or faster than Canon's or Nikon's version?
09-20-2010, 06:45 PM   #141
Pentaxian




Join Date: Sep 2007
Location: Boston, MA
Posts: 7,411
Not until someone actually uses it.
09-20-2010, 07:33 PM   #142
Loyal Site Supporter




Join Date: Mar 2009
Location: Southern Indiana
Photos: Gallery
Posts: 14,957
QuoteOriginally posted by Clarkey Quote
Weather sealing is a unique feature on this zoom range, to be honest I was expecting around $600 USD. Point taken though, I think Sigma has really upped their ante with this years releases/value.
Very true. This could be a great hiking set up 18-135 plus K7/5. Light, weather sealed in a package other than point and shoot -- something that is pretty unique for Pentax as compared to the other major players.
09-21-2010, 12:24 AM   #143
Forum Member




Join Date: Aug 2010
Location: Leiden
Posts: 59
I do not know whether someone has already post this pic of a fully extended 18-135:



09-21-2010, 12:41 AM   #144
Veteran Member
KungPOW's Avatar

Join Date: Nov 2007
Location: Vancouver, Canada
Photos: Gallery
Posts: 1,702
QuoteOriginally posted by Stringmike Quote
..as already discussed may be Pentax's answer to a simple direct electric drive focusing motor. It does not operate at ultrasonic frequencies but from the patent appears to use pulsed direct current (DC). The design drives the focus ring by magnetic coupling and is mechanically very simple. The electronic drive circuitry is also lower voltage and simpler than those used for ultrasonic motors.

My guess would be that the poor reliability of SDM has given Pentax an incentive to go with a new design.

Mike
So, if the new patent uses pulsed DC curent, then this lens might be the first with the new drive. Or, it is just a DC micro motor (like all other SDM lenses I understand), and the DC code is not to indicate a new drive, but a revamped micro motor drvie.

Maybe Pentax is going to start using true ultrasonic ring motors. These use high frequency AC current. So maybe we will see AC SDM lenses for the true ring motors, and DC SDM lenses for the micro motors.

Either way, Pentax has, or is changing the SDM drive system.

Someone needs to take a lens apart and tell us what they find inside.

I nominate Falk, as he is at Photokina.
09-21-2010, 12:43 AM   #145
Veteran Member




Join Date: Sep 2006
Location: Netherlands
Photos: Gallery
Posts: 908
QuoteOriginally posted by fzwo Quote
It certainly is not the same construction as the Tokina.

About the focus motor: Yes, unfortunate name choice. .
Come on, it is not a bad effort by a company with brought us DSLR's like *ist. *istD, *istDs....
09-21-2010, 12:44 AM   #146
Veteran Member




Join Date: Sep 2006
Location: Netherlands
Photos: Gallery
Posts: 908
QuoteOriginally posted by KungPOW Quote
So, if the new patent uses pulsed DC curent, then this lens might be the first with the new drive. Or, it is just a DC micro motor (like all other SDM lenses I understand), and the DC code is not to indicate a new drive, but a revamped micro motor drvie.

Maybe Pentax is going to start using true ultrasonic ring motors. These use high frequency AC current. So maybe we will see AC SDM lenses for the true ring motors, and DC SDM lenses for the micro motors.

Either way, Pentax has, or is changing the SDM drive system.

Someone needs to take a lens apart and tell us what they find inside.

I nominate Falk, as he is at Photokina.
The ring motor patent was from december 2009, I very much doubt if it could already be implemented
09-21-2010, 12:46 AM   #147
Pentaxian




Join Date: Apr 2007
Location: Sweden
Posts: 1,887
QuoteOriginally posted by zackspeed Quote
new motordesign.
dc motor like in patent,but without the old af gear.

ROTARY ACTUATOR
That patent does not describe a Direct Current (DC)-motor. A direct current motor runs on direct current, the one described in the patent needs alternating phases or pulses to run.

A DC-motor is usually found in the cheapest of toys. So it's probably a new micromotor with a new name to differentiate it from the old ones. Nothing fancy at all.
09-21-2010, 12:47 AM   #148
Veteran Member




Join Date: Sep 2006
Location: Netherlands
Photos: Gallery
Posts: 908
QuoteOriginally posted by Rondec Quote
Very true. This could be a great hiking set up 18-135 plus K7/5. Light, weather sealed in a package other than point and shoot -- something that is pretty unique for Pentax as compared to the other major players.
K-5 may be priced a bit high but the K-5 + 18-135 combo is very nice priced considering what other brands ask
09-21-2010, 01:50 AM   #149
Veteran Member
Steelski's Avatar

Join Date: Jan 2008
Location: Varna
Posts: 468
QuoteOriginally posted by Gimbal Quote
That patent does not describe a Direct Current (DC)-motor. A direct current motor runs on direct current, the one described in the patent needs alternating phases or pulses to run.

A DC-motor is usually found in the cheapest of toys. So it's probably a new micromotor with a new name to differentiate it from the old ones. Nothing fancy at all.
I think you need to read the patent. It talks about DC motor.
page 12!!!
09-21-2010, 02:00 AM   #150
Veteran Member
blende8's Avatar

Join Date: Feb 2007
Location: Bremen, Germany
Photos: Albums
Posts: 1,484
Perhaps Pentax wants to avoid the term SDM, because it carries very negative connotations in the Pentax community and rightly so.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
18-135mm, camera, dc, lens, pentax, pentax news, pentax rumors, pentax-da, sdm, smc, thanks, wr
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Need advice: Pentax SMCP-FA 135mm f/2.8 vs smc PENTAX DA Star 50-135mm F2.8 ED bladerunner0427 Pentax SLR Lens Discussion 35 12-03-2010 07:17 AM
For Sale - Sold: Pentax SMC Fzoom 250-600mm F5.6ED asa3dpro Sold Items 51 02-26-2009 12:04 PM
Considering reasonable offers on my Pentax SMC Fzoom 250-600mm F5.6ED asa3dpro Photographic Technique 4 02-19-2009 08:50 AM
Review: smc PENTAX-DA 50-200mmF4-5.6ED SpecialK Pentax SLR Lens Discussion 1 01-05-2007 11:41 PM



All times are GMT -7. The time now is 09:11 PM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top