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01-30-2011, 01:02 PM   #1
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DA 40mm noisy & slow af ?

I've just bought a 40mm Limited for on my k-x, happy with the image quality, nice and sharp, focus is spot on. DOF is nice, already made some nice snapshots/portraits of my little boy.

However the speed of autofocus isnt great. I've read in the reviews here that it was really fast, but my copy is a just bit slower than my kit lens. The kitlens most of the time just jumps to focus in one go, Da 40mm seems to overshoot,then move back. The dampening on the focusring feels nice when on mf, but is a lot heavier than on my da15mm. Also when focusing its rather noisy.

Do other people's DA 40mm have the same charactaristics, or did i get a bad copy? The lens arrived without plasic bags around it like my 15mm, but didnt show any signs of ever being mounted (mount was spotless)




01-30-2011, 01:14 PM   #2
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That is strange, I do find it my fastest AF lens.

Maybe you are using the Da 40 in poorer light than the kit lens, due to the wider aperture? Poor light / tungsten will cause you some issues...
01-30-2011, 01:55 PM   #3
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My DA 40 is very quick; however, I don't own a kx, only a K20 and K7. The focus throw is quite short and the glass itself is light, meaning that it can get where it is going really quickly.
01-30-2011, 02:23 PM   #4
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That is strange, a bad copy perhaps? My old DA 40mm was the fastest thing out there =]

01-30-2011, 02:28 PM   #5
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My copy is also very fast to focus and is accurate.
01-30-2011, 02:47 PM   #6
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Well I guess it all depends on what you are use to. The DA40 is the fastest focusing lens I own (3 other zooms and 4 primes), but then I've never used Nikon or Canon ring USM lenses. In Pentax land though the DA40 is as fast as it comes. Any lens is going to be slowest going from closest focus to infinity, is that what you are doing frequently?
01-31-2011, 04:27 AM   #7
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QuoteOriginally posted by twitch Quote
Well I guess it all depends on what you are use to. The DA40 is the fastest focusing lens I own (3 other zooms and 4 primes), but then I've never used Nikon or Canon ring USM lenses. In Pentax land though the DA40 is as fast as it comes. Any lens is going to be slowest going from closest focus to infinity, is that what you are doing frequently?
Then I probably have a bad copy, because i have a DA 15mm just like you and it is a lot faster in auto focus. (which I thought would be logical for an UWA lens)

I've been testing the lens out on some walking people & stationary objects, fast shutterspeed, altenating between focusing on objects about 1 meter and 8 meter away.

Thanks for all the replies, I'll go back to the store, try a different copy, see how that feels.
01-31-2011, 10:18 AM   #8
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The DA 40 is the fastest autofocus lens I own.

Perhaps you can take a video of the lens in action so we can gauge whether or not it's working properly?

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