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06-13-2011, 02:29 PM   #136
Ash
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Is that on the K-5 or the K20D Steve?
My K-5 *does* completely miss focus once in a while as well, regardless of what lens is on it.
Just another quirk of the K-5.

06-13-2011, 02:30 PM   #137
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QuoteOriginally posted by Ash Quote
Is that on the K-5 or the K20D Steve?
My K-5 *does* completely miss focus once in a while as well, regardless of what lens is on it.
Just another quirk of the K-5.
K-5; I haven't thrown it on the K20D to test it. That one has the 18-200 Sigma on it and my wife uses it.
06-13-2011, 02:33 PM   #138
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QuoteOriginally posted by Ash Quote
Just another quirk of the K-5.
I find this to be true of the K20d as well..

I think it's a Pentax quirk.
06-14-2011, 10:49 AM   #139
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QuoteOriginally posted by Ash Quote
Is that on the K-5 or the K20D Steve?
My K-5 *does* completely miss focus once in a while as well, regardless of what lens is on it.
Just another quirk of the K-5.
Is there any camera that doesn't, and when it does miss, how often is it due to user error?

Rob

06-14-2011, 12:14 PM   #140
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QuoteOriginally posted by robgo2 Quote
Is there any camera that doesn't, and when it does miss, how often is it due to user error?

Rob
With some lenses, my K-5's misses are extremely rare. With others, they're common. With my D-Xenon 100mm and my FA35mm, it nails focus... oh, 99% of the time; I can often shoot a hundred images without 'missing'. With others - the FA43, for instance - it hits less than 90% - this weekend, I shot ~50 images of people standing around with the FA43, and six or seven were clear focus misses. The Tamron I sold (on my K-5) would miss 60% of the time. My DA* 50-135 (which is virtually flawless on the K20D) misses about 5% of the time; same for Bigma. (This is just going by the first cull numbers, where I zoom to 100% and trash everything that's out of focus).

I would chalk it up to user error if, say, certain focal lengths missed a lot, or if there was some difference in use case, but honestly, I use the FA35 and the FA43 virtually interchangeably, and there's a clear difference in their AF consistency.
06-14-2011, 01:10 PM   #141
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QuoteOriginally posted by jstevewhite Quote
With some lenses, my K-5's misses are extremely rare. With others, they're common. With my D-Xenon 100mm and my FA35mm, it nails focus... oh, 99% of the time; I can often shoot a hundred images without 'missing'. With others - the FA43, for instance - it hits less than 90% - this weekend, I shot ~50 images of people standing around with the FA43, and six or seven were clear focus misses. The Tamron I sold (on my K-5) would miss 60% of the time. My DA* 50-135 (which is virtually flawless on the K20D) misses about 5% of the time; same for Bigma. (This is just going by the first cull numbers, where I zoom to 100% and trash everything that's out of focus).

I would chalk it up to user error if, say, certain focal lengths missed a lot, or if there was some difference in use case, but honestly, I use the FA35 and the FA43 virtually interchangeably, and there's a clear difference in their AF consistency.
Pardon my asking, but have you calibrated the FA43 on your K-5? If yes, then I would advise sending the camera with lens to Pentax for service. An error rate of greater than 10% is unacceptable.

Rob
06-14-2011, 01:19 PM   #142
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QuoteOriginally posted by robgo2 Quote
Pardon my asking, but have you calibrated the FA43 on your K-5? If yes, then I would advise sending the camera with lens to Pentax for service. An error rate of greater than 10% is unacceptable.

Rob
No pardon necessary; it's a reasonable question. Let me say that I have tried. In any situation using a test target I can create, the FA43 performs admirably. I've tried four or five test targets published on the interwebs. Wide open and independent of light source (daylight CFLs, tungsten, soft white CFLs, etc), it nails it every time. Furthermore, real world shooting has shown that it doesn't always 'miss' in the same direction; sometimes it misses forward, sometimes backward. I have not tested it on my K20D, but my DA*50-135 misses about 5% of the time on my K-5, and virtually never on my K20D.

It's hard to lay it at the door of the K-5, though, because many of my lenses perform *flawlessly* on the K-5. Particularly the two I use the most - the FA35 and the D-Xenon 100 - nail focus nearly every time, exactly where I think it ought to be. So does Bigma. I need to shoot with my Sigma 18-50 f2.8 and see how it does, I suppose.

So to answer your question, I have been unable to calibrate the FA43; any AF fine adjustment causes an increase in missed shots, not a decrease.

I might end up sending the camera in, but since I can't replicate the focus problem in controlled circumstances, I don't hold out much hope that Pentax can. I might try finding a focus target that had reduced contrast targets... that's a thought.
06-14-2011, 01:19 PM   #143
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Calibration is important, but if a lens is hitting the mark most of the time, it cannot be a calibration problem (unless miraculously every time the uncalibrated lens hits the mark it is due to chance or consistent user 'error'!).

My biggest problem on the K-5 is the Tamron 28-75, which seems to consistently front-focus despite -10 fine AF adjustment. It needs to be sent away for macrocalibration. All my other lenses are spot on at 0 to -5 fine AF adjustment.

06-14-2011, 01:29 PM   #144
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QuoteOriginally posted by Ash Quote
Calibration is important, but if a lens is hitting the mark most of the time, it cannot be a calibration problem (unless miraculously every time the uncalibrated lens hits the mark it is due to chance or consistent user 'error'!).

My biggest problem on the K-5 is the Tamron 28-75, which seems to consistently front-focus despite -10 fine AF adjustment. It needs to be sent away for macrocalibration. All my other lenses are spot on at 0 to -5 fine AF adjustment.
That's partly my thought, as well. The 50-135, for instance, was abysmal initially, but I dialed in a -5 and it's spot on *most* of the time now (~95%). And, of course, the FA35 and D-Xenon 100mm; they required no adjustment whatsoever, and they are both very accurate even at closest focus distance, where the DOF is measured in fractions of an inch.

I'm not above user error at all, of course. I just have a hard time believing that I could make the same error > 10% of the time with the FA43, but < 2% of the time with the FA35. Oh, and the week that I had a DA70, it was dead on, with about 90 images with no culls due to focus error.
06-14-2011, 02:04 PM   #145
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QuoteOriginally posted by jstevewhite Quote
That's partly my thought, as well. The 50-135, for instance, was abysmal initially, but I dialed in a -5 and it's spot on *most* of the time now (~95%). And, of course, the FA35 and D-Xenon 100mm; they required no adjustment whatsoever, and they are both very accurate even at closest focus distance, where the DOF is measured in fractions of an inch.

I'm not above user error at all, of course. I just have a hard time believing that I could make the same error > 10% of the time with the FA43, but < 2% of the time with the FA35. Oh, and the week that I had a DA70, it was dead on, with about 90 images with no culls due to focus error.
So far, I have found the FA43 to be highly accurate on my K-7. You should send yours in for service. It is no fun using a lens that you cannot trust to focus accurately, especially a lens of this caliber and cost. The 43 Limited has been around since 1997, and all of the bugs should have long ago been worked out. You may be experiencing an isolated problem with camera/lens interaction.

Rob
06-14-2011, 02:06 PM   #146
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QuoteOriginally posted by robgo2 Quote
So far, I have found the FA43 to be highly accurate on my K-7. You should send yours in for service. It is no fun using a lens that you cannot trust to focus accurately, especially a lens of this caliber and cost. The 43 Limited has been around since 1997, and all of the bugs should have long ago been worked out. You may be experiencing an isolated problem with camera/lens interaction.

Rob
Actually, I just told Amazon I wanted to return it and got my labels Thanks for your advice. It gave me a perspective I hadn't considered. I can often be too accepting of flaws when I like the overall function of a device.

edit: I threw it on the K20D; three of ten images were missed focus. That's what decided for me. Once they issue the refund, I'll probably get a DA* 55. For fun.

Last edited by jstevewhite; 06-14-2011 at 02:13 PM.
06-14-2011, 02:13 PM   #147
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QuoteOriginally posted by jstevewhite Quote
Actually, I just told Amazon I wanted to return it and got my labels Thanks for your advice. It gave me a perspective I hadn't considered. I can often be too accepting of flaws when I like the overall function of a device.
I did not realize that yours was a brand new lens, in which case, returning it makes more sense than sending it to Pentax for service. Because the unit is defective, Amazon should pay for the return shipping as well as for the shipping of the replacement unit, should you decide to get one. I certainly would, as I absolutely love this lens.

Rob
06-16-2011, 09:35 AM   #148
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QuoteOriginally posted by jstevewhite Quote
Actually, I just told Amazon I wanted to return it and got my labels Thanks for your advice. It gave me a perspective I hadn't considered. I can often be too accepting of flaws when I like the overall function of a device.

edit: I threw it on the K20D; three of ten images were missed focus. That's what decided for me. Once they issue the refund, I'll probably get a DA* 55. For fun.
I just read in another thread that you are going ahead with exchanging the FA43 for a DA*55. All I can say is that you should test the focusing accuracy of the DA* very carefully. It is notorious for having focusing difficulties that cannot be corrected with simple AF adjustments. Read my review and the one immediately preceding it in the Lens Review section of Pentax Forums and also the formal test report in dpreview for more details.

I wish you good luck with the new lens. You will need luck to get a good copy.

Rob

Last edited by robgo2; 06-16-2011 at 09:40 AM.
06-16-2011, 10:37 AM   #149
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QuoteOriginally posted by robgo2 Quote
I just read in another thread that you are going ahead with exchanging the FA43 for a DA*55. All I can say is that you should test the focusing accuracy of the DA* very carefully. It is notorious for having focusing difficulties that cannot be corrected with simple AF adjustments. Read my review and the one immediately preceding it in the Lens Review section of Pentax Forums and also the formal test report in dpreview for more details.

I wish you good luck with the new lens. You will need luck to get a good copy.

Rob
Thanks again for the advice; I will check it very carefully when I get it. Amazon is amazingly good about exchanges, too. I have high hopes as my DA* 50-135 and a friend's DA* 16-50 both focus dead on with no adjustment, even at closest focus where DOF is paper thin. We'll see. The FA43 I just returned had focusing difficulties that couldn't be corrected with fine adjust, either.

Truth be told, I probably should have just kept my FA50 1.4. But, live and learn, eh? I looked at the Sigma 50mm 1.4, but it's got the same abysmal corner profile that the 30mm 1.4 has, which is what put me off that lens. I can always make corners blurry; you can't make 'em sharp if they aren't. And I'm here because I like Pentax glass, so it makes little sense to invest lots in glass that Pentax also makes - and it's only about 25% more than the Sigma.

Steve
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