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02-27-2012, 09:28 AM   #1
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Question about "DC" on new lens

Recently got the 18-135 WR with DC and love that it's so quiet.

However another question is that if DC breaks down, does the lens stop auto focusing or can still use the screw drive focusing mechanism ?

02-27-2012, 09:55 AM   #2
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Look at the lens mount - do you see a screw drive mechanism? Looks like a regular screw (hence the name). As far as I know, it doesn't, but you've got the lens and can see for yourself.

BTW, while there have been many reports of SDM motors failing, I haven't heard any for DC motors. Might be a positive sign.
02-27-2012, 10:08 AM   #3
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No, it will not focus on older cameras because it does not have the screw drive. Its all Direct Current for this one.

From official Pentax Specs on the 18-135: "This lens is compatible with the PENTAX K-5, K-r, K-7, K-x, K-m, K2000, K20D, K200D, K100D Super and K10D (with firmware v. 1.30 or above installed). When mounted on other camera bodies, the focus mode is automatically switched to manual."
02-27-2012, 10:14 AM   #4
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Besides that it doesn't have a screw-drive the INFO contact says to the camera it has SDM/DC/HSM and if the camera recognize the comment it will use those type of motors and there is no way to force it to use the screw-drive AF.
Because the camera will only use the screw-drive AF if it knows the lens has AF so it needs the INFO contact.

02-27-2012, 10:16 AM   #5
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We've had no reported cases of DC breaking down yet- so you can expect the lens to be quite reliable!

It's a KAF3 lens, so if the AF motor were to fail you would have to focus manually.

Last edited by Bramela; 02-27-2012 at 12:01 PM.
02-27-2012, 12:02 PM   #6
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Just fixed a typo error there, Adam

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