DA*300mm SDM autofocus problem

mechmike10 · 01-05-2016, 03:06 PM

Since last summer, I have been having an ongoing but intermittent SDM autofocus issue with my DA*300mm. While on a trip last summer, the autofocus quit entirely (at a particularly inconvenient time). During the trip, I could not get it to work again no matter what I tried. A few weeks after I returned home, I picked up the lens to check it one more time before deciding to have it repaired or converted to screw drive, and it was working again. Shortly after that, I was out of commission for several weeks with a knee replacement, and I didn't use the lens at all. Today, I picked it up again, and at first, the autofocus was not working. I tried manually focusing the lens while holding the shutter release part way down and it started working again. I have 3 questions.

1. Is this a more or less common problem with this lens? By "this" I mean the SDM going inoperative until you jog it by manually focusing the lens while partially depressing the shutter release.

2. Does anyone know if Eric Henderson will convert one of these lenses to screw drive? Is there another reputable repairman that will do such a conversion?

Let me explain my dilemma. I have a k-3 and a k-5. I realize the k-3 cannot be used to convert an SDM lens to screw drive. I want to sell the k-5, but am hesitant to do so unless I have an alternative to deal with the 300mm if the SDM quits entirely. OTOH, I don't want to mess with the lens if it is working.

**UncleVanya** · 01-05-2016, 03:17 PM

PM sent.

JohnX · 01-05-2016, 03:33 PM

Originally posted by mechmike10

I realize the k-3 cannot be used to convert an SDM lens to screw drive.

If the lens has screw drive, it will work on the K-3, so if you get the SDM disabled on your DA*300, it will work on it too.

mechmike10 · 01-05-2016, 04:06 PM

I understand that. The problem is the k-3 cannot be used to do the conversion.

**Mr. Ed** · 01-05-2016, 08:20 PM

Originally posted by UncleVanya

PM sent.

I currently have a K3 and would be interested if information is available to send off and have converted to screw drive. Thanks

Ivo · 01-06-2016, 03:26 AM

Hi, read this topic. I also had such problem a year ago and conversion was successful.
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/289060-da-3...s-problem.html

01-05-2016, 03:06 PM	#1
mechmike10 Senior Member Join Date: Dec 2007 Location: Mechanicsburg, PA Posts: 176	*DA300mm SDM autofocus problem** Since last summer, I have been having an ongoing but intermittent SDM autofocus issue with my DA*300mm. While on a trip last summer, the autofocus quit entirely (at a particularly inconvenient time). During the trip, I could not get it to work again no matter what I tried. A few weeks after I returned home, I picked up the lens to check it one more time before deciding to have it repaired or converted to screw drive, and it was working again. Shortly after that, I was out of commission for several weeks with a knee replacement, and I didn't use the lens at all. Today, I picked it up again, and at first, the autofocus was not working. I tried manually focusing the lens while holding the shutter release part way down and it started working again. I have 3 questions. 1. Is this a more or less common problem with this lens? By "this" I mean the SDM going inoperative until you jog it by manually focusing the lens while partially depressing the shutter release. 2. Does anyone know if Eric Henderson will convert one of these lenses to screw drive? Is there another reputable repairman that will do such a conversion? Let me explain my dilemma. I have a k-3 and a k-5. I realize the k-3 cannot be used to convert an SDM lens to screw drive. I want to sell the k-5, but am hesitant to do so unless I have an alternative to deal with the 300mm if the SDM quits entirely. OTOH, I don't want to mess with the lens if it is working.

01-05-2016, 08:20 PM	#5
Mr. Ed Site Supporter Join Date: Mar 2014 Posts: 563	Auto focus problem 16-50 2.8* Originally posted by UncleVanya PM sent. I currently have a K3 and would be interested if information is available to send off and have converted to screw drive. Thanks

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01-05-2016, 03:17 PM	#2
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,407	PM sent.

01-05-2016, 03:33 PM	#3
JohnX Pentaxian Join Date: Jul 2009 Location: London Posts: 1,116	Originally posted by mechmike10 I realize the k-3 cannot be used to convert an SDM lens to screw drive. If the lens has screw drive, it will work on the K-3, so if you get the SDM disabled on your DA*300, it will work on it too.

01-05-2016, 04:06 PM	#4
mechmike10 Senior Member Join Date: Dec 2007 Location: Mechanicsburg, PA Posts: 176 Original Poster	I understand that. The problem is the k-3 cannot be used to do the conversion.

01-06-2016, 03:26 AM	#6
Ivo Junior Member Join Date: Mar 2008 Location: Latvia Photos: Gallery \| Albums Posts: 25	Hi, read this topic. I also had such problem a year ago and conversion was successful. https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/289060-da-3...s-problem.html