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09-22-2010, 09:13 PM   #1
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Pentax AF focus issues?

I am happy for any improvements that Pentax makes in this area, but as a current K20D shooter (oh my), I can't complain. I have shot along side two different Canon shooters in very dim light and have bested them in AF capability. (Okay, I had to use AF-C, and let the camera select the focus points, but in some situations, I got focus and they did not. Of course, they were not using Marks---) So why the continued drum beat of anti Pentax AF focus miss-information? I haven't found it to be true.

Michael

09-22-2010, 09:25 PM   #2
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Since the K20D, with K-7, K-x, K-r and now K-5, it's been said AF performance and speed has been improving constantly. I would imagine there's a big difference now between, e.g., K20D and K-5.
09-24-2010, 09:20 AM   #3
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sky- I agree. I started Pentax digital (film for many years back to K 1000 and Spotmatic) with an istDS. Next I moved up to K 10. Then I moved when the K 7 came out. I have noticed incrememtal improvements in AF speed along the way, most noticeably from the K 10 to the K 7. One would expect products to improve and evolve as they mature. But, frankly, I get a bit sick of hearing all the griping about Pentax focus speed, for my needs it has always been quite acceptible. Eds
09-24-2010, 09:42 AM   #4
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Well Eds that really depends on your individual needs doesn't it ? For many it's fine, for just as many it's slow.

However there is no disputing that Pentax AF speeds to date have been a lot slower than CaNikon's - there is no debate, that is a fact. So hopefully the K5 will rectify that.

09-24-2010, 10:47 AM   #5
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QuoteOriginally posted by skyoftexas Quote
So why the continued drum beat of anti Pentax AF focus miss-information? I haven't found it to be true.
AF-C is mostly what people complain about. And low-light AF before Canikon loses ability to focus is faster than Pentax's.
I too don't understand the thought that Canon AF is a lot better...shot w/ a friend w/ a 40D and he had problems getting focus when we were doing sun flare shots but I had no problems...
09-24-2010, 10:53 AM   #6
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QuoteOriginally posted by Frogfish Quote
However there is no disputing that Pentax AF speeds to date have been a lot slower than CaNikon's - there is no debate, that is a fact. So hopefully the K5 will rectify that.
there is dispute, however, on what you describe as 'a lot'
09-24-2010, 04:56 PM   #7
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I believe the main difference is that the dedicated lenses from Canon and Nikon with built-in AF motors, specially the long ones (400mm+), can provide faster focusing than Pentax screwdriver ones, and this where most people whine about Pentax AF. One has to consider the price difference though, as lenses with both AF and IS (equivalent of what you get with a DA lens + body with SR) are on the high-end Canon/Nikon/Sigma offerings and substantially more expensive.

Other than that, it's stated that some models hunt more to AF under low-light, I believe it's particularly because the AF sensor wasn't too sensitive on older models. I know this is something that affects the K-x (I have one), and there are reports it improved significantly on the new K-5/K-r models.
09-25-2010, 05:30 AM   #8
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Speed vs Reliability

QuoteQuote:
However there is no disputing that Pentax AF speeds to date have been a lot slower than CaNikon's - there is no debate, that is a fact. So hopefully the K5 will rectify that.
Canon's AF speed up to its point of non focusing possibly/probably has been faster than Pentax. But differences measured in tenths of seconds are hard to quantify. However, when one camera can focus and the other cannot the difference is indisputable.


Last edited by skyoftexas; 09-25-2010 at 05:31 AM. Reason: Poor grammer
09-26-2010, 08:31 PM   #9
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QuoteOriginally posted by hcarvalhoalves Quote
I believe the main difference is that the dedicated lenses from Canon and Nikon with built-in AF motors, specially the long ones (400mm+), can provide faster focusing than Pentax screwdriver ones, and this where most people whine about Pentax AF. One has to consider the price difference though, as lenses with both AF and IS (equivalent of what you get with a DA lens + body with SR) are on the high-end Canon/Nikon/Sigma offerings and substantially more expensive.

Other than that, it's stated that some models hunt more to AF under low-light, I believe it's particularly because the AF sensor wasn't too sensitive on older models. I know this is something that affects the K-x (I have one), and there are reports it improved significantly on the new K-5/K-r models.
I'm not too sure about that price advantage anymore. I chose the K-x because it was decent price and I could find old, cheap lenses and still could get SR. However, as soon as I got the K-x and it got popular, it became almost impossible to find those old, cheap lenses anymore unless I'm willing to pay 3-4 times what it used to be. As for newer lenses, I don't see much price difference, if any. I don't think it's fair to compare a $400 Pentax lens with no on lens SR and focus engine vs a $450 Canikon lens with both SR and focus engine on the lens. Please don't get me wrong, I love my camera and the ability to have SR on all lenses, but I just haven't seen the price advantage since the K-x came out.
09-26-2010, 09:04 PM   #10
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QuoteOriginally posted by skyoftexas Quote
I am happy for any improvements that Pentax makes in this area, but as a current K20D shooter (oh my), I can't complain. I have shot along side two different Canon shooters in very dim light and have bested them in AF capability. (Okay, I had to use AF-C, and let the camera select the focus points, but in some situations, I got focus and they did not. Of course, they were not using Marks---) So why the continued drum beat of anti Pentax AF focus miss-information? I haven't found it to be true.

Michael
Please don't take offense if I don't believe you. Your evidence is merely anecdotal. The slow AF behavior of Pentax DSLR's in lower light, has been well documented for years in many places. For example, take a look at the pop photo focus speed charts vs light level. All Pentax DSLR's take a "dive" after EV 6. And that is on AF-S. The AF-C is even worse if one attempts to try tracking a moving target in low light.

I often point to these tests that someone posted on youtube. They are consistent with my experience with my k10d, k20d, and k-7, and Canon cameras I have used. SAFOX is at least a decade behind the competition. Only time will tell if the SAFOX IX AF improvements are real, or more smoke...

[YT]http://www.youtube.com/watch?v=ngUcQUchHEU[/YT]
[YT]http://www.youtube.com/watch?v=7-gfkUJA6dY[/YT]
09-26-2010, 09:13 PM   #11
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QuoteOriginally posted by pentaxpup Quote
I'm not too sure about that price advantage anymore. I chose the K-x because it was decent price and I could find old, cheap lenses and still could get SR. However, as soon as I got the K-x and it got popular, it became almost impossible to find those old, cheap lenses anymore unless I'm willing to pay 3-4 times what it used to be. As for newer lenses, I don't see much price difference, if any. I don't think it's fair to compare a $400 Pentax lens with no on lens SR and focus engine vs a $450 Canikon lens with both SR and focus engine on the lens. Please don't get me wrong, I love my camera and the ability to have SR on all lenses, but I just haven't seen the price advantage since the K-x came out.
At least around the used market here or buying on Ebay, I have nothing to complain, specially considering the difference between buying CaNikon bulky zooms vs. buying primes.
09-26-2010, 09:28 PM   #12
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QuoteOriginally posted by PentaxPoke Quote
Please don't take offense if I don't believe you. Your evidence is merely anecdotal. The slow AF behavior of Pentax DSLR's in lower light, has been well documented for years in many places. For example, take a look at the pop photo focus speed charts vs light level. All Pentax DSLR's take a "dive" after EV 6. And that is on AF-S. The AF-C is even worse if one attempts to try tracking a moving target in low light.

I often point to these tests that someone posted on youtube. They are consistent with my experience with my k10d, k20d, and k-7, and Canon cameras I have used. SAFOX is at least a decade behind the competition. Only time will tell if the SAFOX IX AF improvements are real, or more smoke...

[YT]http://www.youtube.com/watch?v=ngUcQUchHEU[/YT]
[YT]http://www.youtube.com/watch?v=7-gfkUJA6dY[/YT]
I'm naive about Canon gear, but aren't those lenses with built-in motors?

Despite SAFOX quality, I would expect the limiting factor to also be the screwdriver's mechanics. I mean, by improving SAFOX they avoid the "hunting", but I wonder if it can affect the actual motor speed.

By experience, I know it also depends a lot on the lens. I have a FA with longer throw which takes way longer than the DA to lock. Speeds might differ between, let's say, DA 18-55 and 100-300 too.

If they diminish the "hunting", and decrease that noticeable delay between motion stop and confirmation beep, I would expect AF to be up to standards, though.

Last edited by hcarvalhoalves; 09-26-2010 at 09:42 PM.
09-26-2010, 10:02 PM   #13
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Please read my post.

QuoteOriginally posted by PentaxPoke Quote
Please don't take offense if I don't believe you. Your evidence is merely anecdotal. The slow AF behavior of Pentax DSLR's in lower light, has been well documented for years in many places. For example, take a look at the pop photo focus speed charts vs light level. All Pentax DSLR's take a "dive" after EV 6. And that is on AF-S. The AF-C is even worse if one attempts to try tracking a moving target in low light.
I was talking about actually being able to achieve focus, not focus speed. I'm sorry you don't believe me, but there is nothing I can do about that.

I have been working with another photographer shooting weddings and he uses Canon cameras. The first wedding we worked together we were both having trouble with focusing at the reception, but I was able to achieve focus by using AF-C and letting the camera select the focus points. I'm pretty sure I read that somewhere and don't claim to be original. By experimentation, I found this to be the only way I can be assured of achieving focus in very dim light.

At another wedding, this same photographer asked the bride and groom to step out side (it was night) for some pictures but gave that up because he could not get focus. I, on the other hand, could.

Last edited by skyoftexas; 09-27-2010 at 05:37 AM. Reason: Too aggressive.
09-27-2010, 05:04 AM   #14
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I had the pleasure to shoot with a friend one night in the office where I work.

One side of the office is floor-to-ceiling glass windows, giving us a nice nightscape, but also problems regarding flash/light reflecting on the glass.

Since I don't have a strobist kit, I had to make do with a flood lamp (yes, a flood lamp, no funds for better gear) fitted with a varistor to control light intensity. A DS, the 18-55 and 50-200 kit lenses, and a cheap tripod compeleted my gear.

To expose for the background, we had to dim the flood lamp. Exposure was about 1-6 seconds at ISO 400, from 4.0 to 8.0 aperture. The light was dim enough that reading of a paper is not easy.

At the same low light levels, my friend's Canon 1000D + (cheap)50mm prime wouldn't lock focus. I can with any of my DS' 9 cross types (with the 18-55 kit), at both horizontal and portrait orientions.

Mind you we were shooting a static subject.

Of course you may argue the 1000D is Canon's bottom rung model, but so is mine, from 5 years ago.

I'm not here to contest or argue about other peoples experience with the Pentax AF, different situations, different needs. Just relating my personal experience.

Now for the bad news:

The tungsten light caused a lot of misfocus on my DS. It locked yes, but not in focus .

So what's better? A K-r with (supposedly) better/faster AF, or a K-7 with the secondary light sensor for better accuracy at tungsten light?

So my experience is the complete opposite of the general notion (or urban legend if you will) that Canon/Nikon AF will at least lock within DOF, while Pentax will just hunt and quit.

P.S.
I'm not here to bash on Canon gear either, and my friend took better photos than I did
09-27-2010, 08:45 AM   #15
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QuoteOriginally posted by skyoftexas Quote
I was talking about actually being able to achieve focus, not focus speed. I'm sorry you don't believe me, but there is nothing I can do about that.

I have been working with another photographer shooting weddings and he uses Canon cameras. The first wedding we worked together we were both having trouble with focusing at the reception, but I was able to achieve focus by using AF-C and letting the camera select the focus points. I'm pretty sure I read that somewhere and don't claim to be original. By experimentation, I found this to be the only way I can be assured of achieving focus in very dim light.

At another wedding, this same photographer asked the bride and groom to step out side (it was night) for some pictures but gave that up because he could not get focus. I, on the other hand, could.
Since most pros use Canon or Nikon gear, this story tells me more about your friends abilities, than it tells me about Pentax AF.
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