Win a Pentax Limited Lens: Raffle Now Live!

leekil · 09-26-2018, 01:55 PM

Has anyone tried this, either intentionally or unintentionally? Could there be damage to the lens, given that the contacts for SDM focusing are the same as the Power Zoom power contacts, but I assume voltage is applied differently in the two cases?

Adam · 09-26-2018, 02:00 PM

Originally posted by leekil

Has anyone tried this, either intentionally or unintentionally? Could there be damage to the lens, given that the contacts for SDM focusing are the same as the Power Zoom power contacts, but I assume voltage is applied differently in the two cases?

Haven't heard of any damage happening (I have tried using a 50-135mm on the MZ-S). The SDM simply doesn't activate because I think that goes through the data contacts.

pschlute · 09-26-2018, 02:32 PM

zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz

ouch....no don't try it !

stevebrot · 09-26-2018, 03:19 PM

Originally posted by Adam

The SDM simply doesn't activate because I think that goes through the data contacts.

Good point! The camera decides which method to use based on the lens mounted and film cameras have no knowledge of in-lens motor models. Ditto for the power zoom lenses for dSLRs.

Steve

Last edited by stevebrot; 09-26-2018 at 05:10 PM.

**twilhelm** · 09-26-2018, 03:31 PM

As long as the SDM lens has screw drive it will auto focus by that means. I've not had any issues or damage using them on my older film cameras. Although the DA17-70 becomes manual focus...

leekil · 09-26-2018, 10:35 PM

Originally posted by stevebrot

Good point! The camera decides which method to use based on the lens mounted and film cameras have no knowledge of in-lens motor models. Ditto for the power zoom lenses for dSLRs.

So maybe in both cases, the voltage is always applied to the lens, but there is nothing that activates the power zoom or autofocus until you either turn the zoom or the camera gives a signal to the lens to focus.

09-26-2018, 01:55 PM	#1
leekil Pentaxian Join Date: May 2016 Photos: Albums Posts: 2,003	SDM lenses on film cameras with Power Zoom contacts Has anyone tried this, either intentionally or unintentionally? Could there be damage to the lens, given that the contacts for SDM focusing are the same as the Power Zoom power contacts, but I assume voltage is applied differently in the two cases?

09-26-2018, 02:00 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,608	Originally posted by leekil Has anyone tried this, either intentionally or unintentionally? Could there be damage to the lens, given that the contacts for SDM focusing are the same as the Power Zoom power contacts, but I assume voltage is applied differently in the two cases? Haven't heard of any damage happening (I have tried using a 50-135mm on the MZ-S). The SDM simply doesn't activate because I think that goes through the data contacts. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
DA Star 16-50 power zoom contacts	Daedbird	Repairs and Warranty Service	2	12-24-2017 01:35 PM
K-mount power zoom/SDM/DC power contacts: is it limiting AF drive speed?	bwDraco	Pentax SLR Lens Discussion	1	08-18-2015 05:34 AM
FA power zoom contacts	Phot0n	Pentax SLR Lens Discussion	6	03-24-2011 04:39 PM
645D, K-m2 and NEW LENSES DA10-16/4 SDM, DA20/2 SDM, DA*28/2 SDM	ogl	Pentax News and Rumors	165	08-11-2010 03:26 AM
For Sale - Sold: Takumar A 2x TC with contacts. Teleplus 2x TC with contacts	Peter Zack	Sold Items	4	08-25-2009 07:49 PM

09-26-2018, 02:32 PM	#3
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,219	zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz ouch....no don't try it !

09-26-2018, 03:19 PM	#4
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Adam The SDM simply doesn't activate because I think that goes through the data contacts. Good point! The camera decides which method to use based on the lens mounted and film cameras have no knowledge of in-lens motor models. Ditto for the power zoom lenses for dSLRs. Steve Last edited by stevebrot; 09-26-2018 at 05:10 PM.

09-26-2018, 03:31 PM	#5
twilhelm Loyal Site Supporter Join Date: Feb 2009 Location: Florida Photos: Gallery \| Albums Posts: 2,369	As long as the SDM lens has screw drive it will auto focus by that means. I've not had any issues or damage using them on my older film cameras. Although the DA17-70 becomes manual focus...

09-26-2018, 10:35 PM	#6
leekil Pentaxian Join Date: May 2016 Photos: Albums Posts: 2,003 Original Poster	Originally posted by stevebrot Good point! The camera decides which method to use based on the lens mounted and film cameras have no knowledge of in-lens motor models. Ditto for the power zoom lenses for dSLRs. So maybe in both cases, the voltage is always applied to the lens, but there is nothing that activates the power zoom or autofocus until you either turn the zoom or the camera gives a signal to the lens to focus.

SDM lenses on film cameras with Power Zoom contacts

Win a Pentax Limited Lens: Raffle Now Live!