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10-31-2010, 02:39 PM   #1
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DA 55-300mm focus adjustment question

Hello all,

many apologies if this is an FAQ - searched and couldn't find any information. I just received a DA 55-300mm from Amazon, which I've been very excited about. However, I have noticed one anomaly when trying out quick shift. The lens correctly focuses to infinity with the camera AF, but the focus ring still has another few degrees of free rotation. It seems to me that the lens is out of adjustment, because I'm used to the focus ring of a lens stopping at infinity. However, for all I know, this is normal for quick-shift lenses. Can anyone let me know? Also, when I was opening the package for the first time, the box lid was not closed, and while everything was packaged well, the manual has a fold on the back, and I did not have to open any seals - is this normal for a NIB Pentax lens, or did amazon send me a returned lens?

Oh, and I'm using a k-x, if it matters... thanks very much for any help!!

10-31-2010, 03:14 PM   #2
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This is no anomaly. All my lenses, quick shift or no, even my third party Sigmas (or especially the Sigmas), can turn slightly beyond infinity. Manually turning the lenses to where they stop reveals that infinity is indeed not in focus. Many of them clearly label the infinity mark in a spot that is very obviously not the end of the focus ring. Even those where it appears that it is at the very end can be shown to have a very slight amount of room to turn after that.

I'm fairly certain this is a manufactured tolerance to prevent excessive wear and tear on the AF system from the focus ring always impacting the end. Also, it gives some room for micro focus adjustment.

The camera doesn't care what the numbers on the scale say anyway. It will focus to whatever it believes is in focus, no matter what the lens says. Infinity is rarely exactly on the infinity mark, it's just an approximation. If it's sharply in focus, that's all that matters.

Last edited by Cannikin; 10-31-2010 at 03:28 PM.
10-31-2010, 04:52 PM   #3
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Those lenses are especially made for Buzz Lightyear.
10-31-2010, 08:53 PM   #4
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cannikin: thanks a bunch, that makes me feel better I'm used to old manual focus lenses where I can just slam them over to infinity and go...

arpe: huh?

11-01-2010, 05:17 PM   #5
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QuoteOriginally posted by acrollet Quote
arpe: huh?
"To infinity and beyond!" Y'know - the Toy Story movies.
11-01-2010, 06:00 PM   #6
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QuoteOriginally posted by Arpe Quote
"To infinity and beyond!" Y'know - the Toy Story movies.
oh, i get it
11-01-2010, 06:31 PM   #7
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QuoteOriginally posted by Arpe Quote
"To infinity and beyond!" Y'know - the Toy Story movies.
very droll
11-03-2010, 01:19 AM   #8
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Thank you, thank you.

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