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06-23-2011, 08:56 AM   #1
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A possible broken SDM on a brand new 16-50

Hi guys, sorry to post this but couldn't find any information about this particular issue.
I bought a brand new Pentax 16-50 from B&H (actually a friend from NY got it for me and arrived yesterday), I didn't have my K-7 with me so I first tried it on a ist*DS and screw-drive autofocus works fine, then when I put it afterwards on my K-7 it won't autofocus, even worse when everything is set to autofocus (on both the lens and camera) the screen keeps flashing (so it doesn't allow me to even enter a menu since it disappears after 0.5s) and in the viewfinder the MF light just flashes on and off, if I turn everything to manual focus it works fine.

Since it's new I'll send it to NY (I live in Quito, Ecuador) to exchange the lens but if I can avoid the shipping costs I'd try to.

It's upsetting because I was undecided between this and the tamron for this very issue, but I at least expected to get a couple of years out of it.

Thanks for the help guys, have a good day, hopefully it's just a small issue, we'll see.

Thanks for the help,
Daniel

06-23-2011, 09:19 AM   #2
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Have you tried cleaning the contacts on the camera and the lens?
06-23-2011, 09:46 AM   #3
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Yes I did, however I'll try again today with some alcohol, mainly because of the behavior of the camera going crazy like that I just can't believe it's misinformation being sent by a crazy and broken SDM but instead (and hopefully) it will be more of a problem in the contacts.
Any suggestion (apart from alcohol) as the best way to clean the contacts?

Thanks.
06-23-2011, 10:01 AM   #4
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QuoteOriginally posted by desc4d Quote
Any suggestion (apart from alcohol) as the best way to clean the contacts?
Pencil eraser.

06-23-2011, 10:06 AM   #5
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Clever idea, I'll try it tonight.
I pray it isn't the lens and a $0.10 pencil eraser would save my ass.
I'll let you know in the evening how it works out.
06-23-2011, 10:08 AM   #6
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This is actually much different behavior than SDM usually causes. I really think you have something else going on.
06-23-2011, 10:33 AM   #7
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So you don't think is the lens?
It's a possibility after all but I'm not entirely sure, I might try to find someone around with another Pentax that supports SDM to try it but so far I can't find no one.
06-23-2011, 10:49 AM   #8
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It could be the lens, I just don't think it's necessarily an SDM problem, or at least it's not the typical SDM problem.

06-23-2011, 12:19 PM   #9
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Well it could be, I only found another guy with this problem in this thread:
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/22187-da%2A-16...king-k10d.html

But apparently he moved to N or C and is no longer here to reply because sent him a pm and he hasn't posted for a couple of years, hopefully he is still there.
06-23-2011, 12:40 PM   #10
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QuoteOriginally posted by Parallax Quote
Pencil eraser.
I hate to say this but using eraser is a poor practice imho because it is abrasive and will scratch the metal which will be prone to oxidation down the road. Clean the contacts with alcohol. If that didn't work, there is DeoxIT. If that failed too, the lens is junk (which I think already is).
06-23-2011, 12:53 PM   #11
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Use your *ist DS to focus the lens to the other end of focus range, i.e. if it is now close to near end, then focus it to infinity end, & vice versa. After this, put it back to your K7 and try.

However, the screen flashing is weird. It seems the lens is draining out your battery. Don't keep trying on your K7. Try above method. If it doesn't solve it, send back to B&H.

Good luck!
06-23-2011, 12:54 PM   #12
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Dude, I see that you are new so let me take this opportunity to welcome you to the club.

I mean, not just to the PF, but to the club of people with broken DA*16-50

Brace yourself because there are some on here who'd argue tooth-and-nail that its just your concoction and there are no real issues with SDM because Pentax has never officially acknowledged it.

But you'll get used to it and things will get better. You'll be hooked on the high quality of optics in your 16-50 and also to the fact of accepting it for its limitations. My last copy of the same lens, 4th to be exact, just didn't work out of the package brand new. But after a lot of sweet-talking it started to move, but it still kicks and screams, literally, as it always takes a while to warm up to me.
06-23-2011, 01:06 PM   #13
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Hehe, well I'll try to clean it with alcohol and what Hyyz said.

Esbee, I hate your club but I embrace it. The optics look fantastic and hold the lens is a wonder, I bought a 5 year warranty just because of this so that'll help, in the meantime let's see if the sweet-talking moves the heart of this beauty.
06-23-2011, 01:17 PM   #14
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QuoteOriginally posted by wlachan Quote
I hate to say this but using eraser is a poor practice imho because it is abrasive and will scratch the metal which will be prone to oxidation down the road.
You're right, there is a risk; particularly if used aggressively or frequently so I would not recommend it for routine maintenance.
06-24-2011, 10:31 AM   #15
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Well I had no luck with all the methods, so asap it goes back to B&H, I do love the lens however so I'll just get a replacement and ask for it to be fully tested. Thanks guys.

Daniel
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