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04-22-2010, 12:13 PM   #1
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FA31mm/FA77mm - a bit more zff zff?

Hey folks,

Hopefully this is in the right section!

I have an FA31 and an FA77 which I use as my go to lenses.

Now, one thing I've found is that the autofocus takes a bit more time on the FA31 and the FA77 than it does on, say, DA limited lenses. Most notably, the FA31 takes that extra zff zff before I get autofocus confirmation.... especially in low light.

I use a K10D (up for sale) and a K20D as my primary cameras and have considered the K7 and possibly the K-x. Since I shoot a lot of "low light indoor hardcore candle light only not your run of the mill everyday darkness with maybe a small LED or something" light... (cough), I was wondering if upgrading to a K-7 or K-x would solve this? Or is this just the nature of the FA31 lens - to have a bit more turns before it confirms?

04-22-2010, 02:11 PM   #2
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QuoteOriginally posted by dugrant153 Quote
Hey folks,

Hopefully this is in the right section!

I have an FA31 and an FA77 which I use as my go to lenses.

Now, one thing I've found is that the autofocus takes a bit more time on the FA31 and the FA77 than it does on, say, DA limited lenses. Most notably, the FA31 takes that extra zff zff before I get autofocus confirmation.... especially in low light.

I use a K10D (up for sale) and a K20D as my primary cameras and have considered the K7 and possibly the K-x. Since I shoot a lot of "low light indoor hardcore candle light only not your run of the mill everyday darkness with maybe a small LED or something" light... (cough), I was wondering if upgrading to a K-7 or K-x would solve this? Or is this just the nature of the FA31 lens - to have a bit more turns before it confirms?
I don't know if upgrading to K-7 will help.
I only have experience with K10D where I only can confirm your findings. 31ltd does take a bit to get things right but 99% of shots (providing your cam is focusing accurately with the lens) are spot on!
When I compared it to my DA40 I used to have, it's focus speed was much faster but got things wrong more often!
I suppose focusing throw may have something to do with it too...

anyway, if you are after really fast AF lens from Pentax, DA40, F50/1.7 and FA135 would be my personal recommendations!

Peter
04-22-2010, 02:14 PM   #3
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The K-x does not have a focus beam so it will probably be worse. I have a DA 40mm & even it struggle to focus in extreme low light on my K-x
04-22-2010, 02:22 PM   #4
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Low light & no AF assist is a recipe for sluggish AF performance.
I would be more confident with the K-7 doing the job faster in that regard.
Be weary that the large focus throw of these FA ltds account for much of the reason why they're not the fastest AF performers around.

04-23-2010, 08:57 AM   #5
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I have a K-7 with both those lenses, and used to use them on a K20. They focus very fast in good light--much faster than the K20. The difference is most noticeable on the FA77 and the FA43 which have longer focus throws. (The throw on the 31 is only 90, which isn't too long compared to the FA77 which is about 180.)

In poor lighting I find it's a lot better when things are close up and have good contrast. Just a zip right to the object and a lock. Trying to focus on something in the middle of the room, well, I think all Pentax cameras want good light! In really low light, one of those $8000 Nikons should do it!

One weird thing--if you're a fan of SR (and in low light, who isn't), and you use AF-S, the focus will lock before the SR hand shows up. A little annoying, and never noticed that on the K20, but the focus was so much slower maybe it's the same amount of time.
04-23-2010, 03:37 PM   #6
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QuoteOriginally posted by Ash Quote
Be weary that the large focus throw of these FA ltds account for much of the reason why they're not the fastest AF performers around.
And another reason I like them, since I prefer manual focus. I guess it's difficult to make a lens that is perfect for both.

P.S. You are not "weary" unless you are tired. But you might be "wary" or cautious. Just sayin'.
04-23-2010, 03:51 PM   #7
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QuoteOriginally posted by rparmar Quote

P.S. You are not "weary" unless you are tired. But you might be "wary" or cautious. Just sayin'.
Please--let's not get into the spelling and grammar police thing here.
04-24-2010, 09:41 PM   #8
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yar. the FA31 and FA77 are superb for manual focusing! I like manual focusing, but sometimes it so dark or so uncontrasty that my eyes can't see anything! In which case, I try to throw it in AF... which may be a tad slow but gets the job done most of the time...

I'm using lots of AF right now, but maybe time for me to go back to manual focus mode!!

04-25-2010, 12:48 AM   #9
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my K-7 is a bit snappier when focusing the FA limited lenses, but it isn't a night an day difference, the camera is just more certain when it locks onto focus...it doesn't adjust itself the way the K10/K20 does.
04-25-2010, 03:22 AM   #10
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QuoteOriginally posted by dugrant153 Quote
yar. the FA31 and FA77 are superb for manual focusing! I like manual focusing, but sometimes it so dark or so uncontrasty that my eyes can't see anything! In which case, I try to throw it in AF... which may be a tad slow but gets the job done most of the time...
Maybe it's my camera but I have found that if I cannot see then the camera definitely can't. It never manages to AF in light too dim to manual focus. it would be great if it did! This came up only just yesterday at a poetry reading. Being in a dim pub I had to crank ISO and do my best with manual focus on the FA 77 Limited. I might post some results if I get them processed.
04-25-2010, 06:29 AM   #11
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If I recall right the K7 did have just a tad quicker focus lock on both lenses. But The 77 was slow regardless of light amount. Its know for its slow focus. The 31 seemed quick to me, much faster than the 77. I never really manual focused either lens much because both were spot on and my manual focusing skills didn't make the 77 any faster.
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