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12-24-2009, 07:02 AM   #1
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"The AF speed is very fast on the K10D."

Quoted from Photozine regarding the FA 77mm.

This is one of the criteria I have been weighing in deciding between the 70mm and the 77mm. There are a lot opinions expressed about the 77mm having slow AF. Now I am confused. Help!

Thanks in advance,
Michael

12-24-2009, 07:13 AM   #2
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I can't really say anything about those two but if the AF speed differene is as beetween FA31 and DA40, you have nothing to worry about. Yes 40 is faster to AF but at 98% of the time you wouldn't notice.
BR
Peter
12-24-2009, 07:47 AM   #3
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QuoteOriginally posted by skyoftexas Quote
Quoted from Photozine regarding the FA 77mm.

This is one of the criteria I have been weighing in deciding between the 70mm and the 77mm. There are a lot opinions expressed about the 77mm having slow AF. Now I am confused. Help!

Thanks in advance,
Michael
Pentax in general has slow AF. Someone just posted a video comparing (I think) a K7 to a Canon 7D where the Pentax came up looking really slow.
One of the things I noticed while watching said video is that the focus throw on the Pentax lenses seems much longer.
I suspect this accounts for some of the speed difference.
Not withstanding the reasons for it, if you want or need really fast AF, Pentax is not your friend.
To go directly to your question, I have both the 70 and 77 mm lenses. The 70 does AF faster, but it's not a huge difference.
Regarding image quality, a lot of people wax eloquent about the 77 being God's gift to photography.
It's a good lens, but when I compare shots from it to shots from my 70, I'm not seeing where the 77 is quantifiably better than the 70.
12-24-2009, 07:56 AM   #4
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Is it the ePhotozine or photozone?

12-24-2009, 08:02 AM   #5
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I'll bow to Wheatfield's opinion on this one as he has both lenses. Come to think about it he has just about every lens for that matter.

I have the DA 70/2.4 and the K10. I find it plenty fast enough for my purposes and the IQ is just great. There is no bad choice with either lens.

Tom G
12-25-2009, 02:48 AM   #6
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QuoteOriginally posted by Wheatfield Quote
One of the things I noticed while watching said video is that the focus throw on the Pentax lenses seems much longer.
I suspect this accounts for some of the speed difference.
Not withstanding the reasons for it, if you want or need really fast AF, Pentax is not your friend.
The most likely reason for the longer focus throw is to enable more precise manual focusing, which is what some people prefer to use. With most cameras capable of video recording, manual focusing ability may soon get back in demand. The longer throw in these AF lenses is really a compromise as their throw is usually less than half the throw you would get on a manual focus lens.
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