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07-20-2012, 03:37 AM   #31
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I express the skepticism. All three of my primes are Pentax. The FA35 in low light appears to have a front focus tendency.

From my blog, here is an example:




It could be the movement, it could be the large AF points, but as I said, it's a Pentax lens and it does give more soft or mis-focus events than the F50 1.7 and my m85 using catch in focus. The M85 with catch in focus is actually a pretty stunningly sharp lens. One must be careful to not go extremely fast with the focus ring, however. This was not the only soft/mis/front focus event I've had with the FA35.

So it depends on the lens and Pentax lenses are not immune to it. The F50 1.7, so far, might have had zero events in my experience, which included similar situations.

07-20-2012, 03:44 AM   #32
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There's missed focus, then there is front-focus...

All I was saying is that I think my AF Pentax lenses perform more reliably than my non-Pentax lenses in AF and exposure terms (with the possible exception of my Sigma 70-200, so far). The 3rd party lens makers can't reliably reverse engineer what Pentax is doing, I suspect.

Last edited by rawr; 07-20-2012 at 03:50 AM.
07-20-2012, 03:50 AM   #33
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And to be fair, it was set at F2. which compounds the issue of where to focus. It could have even focused on the hand and bottle, which is closer to the plane the two in-focus people are in front of the guy with the hat. Will never know, but I used the shot anyhow because of what it was.
07-20-2012, 03:59 AM   #34
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QuoteOriginally posted by snake Quote
nd to be fair, it was set at F2. which compounds the issue of where to focus.
If the focus mode was the 11 point matrix, the camera can grab ahold of anything contrasty in the AF sensor zone like the guy with the phones face, or something else on that plane it saw as contrasty. But the guy in the middle with a striped shirt would have made a ideal contrasty focus target too, I would have thought.

Either way it is still a good shot, with several layers of visual interest happening.

07-20-2012, 04:06 AM   #35
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QuoteOriginally posted by rawr Quote
If the focus mode was the 11 point matrix, the camera can grab ahold of anything contrasty in the AF sensor zone like the guy with the phones face, or something else on that plane it saw as contrasty. But the guy in the middle with a striped shirt would have made a ideal contrasty focus target too, I would have thought.

Either way it is still a good shot, with several layers of visual interest happening.
Thanks for the compliment.

It was set to centerpoint, as I feel I'm not always too experienced to use multi reliably under such fast-moving, spontaneous situations. If I play too much, the moment is gone (over 1/4 of the city's population goes to this quarter during the festival and even movement becomes restrictive or not under your control, but the will of the dense crowds).
07-21-2012, 08:25 AM   #36
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QuoteOriginally posted by cali92rs Quote
I respectfully disagree. My D90 was faster and more accurate than my newer, more expensive K-5.
I had a D90*, and now I use a K-5. AF speed on both is somewhat lens dependent. For example, comparing kit lenses, with the 18-135 mounted, the K-5 focuses faster than the D90 with the 18-105. I suspect that the Nikon's AF advantage will be more apparent with fast, "pro" lenses. I haven't used either, but by reputation, the Nikon 17-55 will focus a lot faster than the Pentax 16-50.

The lack of really fast motorized lenses may be as big an obstacle to Pentax matching Canikon AF as the AF systems in its camera bodies.

That said, I have found the K-5's AF to be more than good enough for my needs. I don't shoot team sports, especially in low light, but I have photographed foot races using 5 point continuous AF with good success. I photographed a theater rehearsal the other afternoon. The light was poor, and with the Tamron 17-50 mounted, the K-5's AF struggled. However, when I mounted either the 40 or the 70 limited, things got better.

Would I like a Pentax body with AF like the D300's? Absolutely. But there are always tradeoffs.

Jeff

*I still have the D90 and a couple of lenses that I am trying to sell.
07-21-2012, 05:49 PM   #37
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The K-5's AF system is this good (with the FA* 85);










AND this bad (w/ Sigma 30mm f/1.4):


Last edited by Crosshair; 07-21-2012 at 06:08 PM.
07-21-2012, 07:10 PM   #38
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I count that as another plus for the proposition that Pentax lenses somehow work better than non-Pentax lenses for AF and exposure

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