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08-16-2009, 07:09 AM   #1
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pentax da* lens problems

I am back with further data on a previous problems I encountered with these lenses mainly 50 135 attached to a k200 body.
I have been in touch with Pentax Australia and they say there is no problem but I say there is.
simply put it is this: the lens works fine on automatic i.e. sports mode, av, or p mode when the conditions are right example a sunny day.
when the day is overcast the lens continually takes out of focus pictures on the same presets i.e. on auto functions.

What Pentax Australia are saying is that the camera and lens doesnt always work on automatic, but this is never stated anywhere.So what is going on?
The lens took great pics when the sun was out. I have taken hundreds more pics to confirm this data.

In my line of work I dont have time to change settings every time I shoot, things happen to fast.

Any idea out there what my next step would be.

08-16-2009, 01:23 PM   #2
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QuoteOriginally posted by ranters Quote
simply put it is this: the lens works fine on automatic i.e. sports mode, av, or p mode when the conditions are right example a sunny day.
when the day is overcast the lens continually takes out of focus pictures on the same presets i.e. on auto functions.
Any idea out there what my next step would be.
Focusing has nothing to do with what exposure mode you're in. Are you sure there are no other factors involved?
08-16-2009, 02:21 PM   #3
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So you mean AF is not accurate in low light?
But you're mentioning different modes... how do these relate at all?
It's important to check your focusing in the viewfinder before releasing the shutter.
Most of the time you wouldn't need to, but in cases where focusing is more difficult, it's best to 'see' things clearly in the VF and point the AF point at the right place before the picture's taken.
08-16-2009, 03:18 PM   #4
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On cloudy days, contrast is less. Which might indeed make AF hunt more, and perhaps lock on soemthing other than what you intended. This isn't unique to DA* lenses, of coure, or to DA, or to Pentax; it's just how phase detect AF works. Examples shots (with EXIF) might help.

08-17-2009, 04:59 AM   #5
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QuoteOriginally posted by Marc Sabatella Quote
On cloudy days, contrast is less. Which might indeed make AF hunt more, ...
I don't know how dark cloudy days are in Australia, but I've never had problems using AF in cloudy days or even in dusk. And all of my AF lenses are slower than F2.8...
08-17-2009, 07:33 AM   #6
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Hi,
I have k200d and 50-135, mostly use Av and never had a problem focusing.
Sure, when it's dark enough it takes a while to focus or, if you try to focus on a featureless object (no contrast). A few months ago I compared focusing between 16-50 vs 50-135 and AFAIR it took the latter about twice as much time to go end-to-end. So if you shoot fast action you need to learn how to do it with this combo.
In any case, I think you need to test it in a controlled environment and post pictures, so people here would be able to tell if it's you or camera/lens.
Good luck,
08-17-2009, 07:52 AM   #7
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Maybe its the SR

I have the 50-135 with the K20 and have the K10 that i haven't tried much with it.

The 50-135 is focusing fine with me, even taking pictures at an open air Shakespeare play in the evening two days ago.

If you're using SR, it takes some time for that to click in, i think its possible to look at your metadata on the unfocused pictures and see if sufficient time elapsed for it to start working. One way of troubleshooting this, is to focus on a tripod with the SR off. If you're getting good af in the evening, then its not the contrast or light, its SR or some other cause.

I was taking pictures at 3200 ISO with the 50-135 last night and had no problems focusing. I think you need to give us more information like shutter speed, aperture, SR on or off, tripod yes or no,? You sound frustrated and thats understandable. But its probably a technique issue. Keep working on it, there is an answer.

best wishes,
08-17-2009, 08:48 AM   #8
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And just FYI for the folks that will post on this thread. This guy was causing a lot of commotion around a thread (created by him) named "DA* lens rubbish"...

And if you really think it is a problem, exaggerate a bit with the Pentax repair. Usually gets the job done.

And i still don't understand. Does the mode dial magically make your AF work and not work? Go get an alcohol swab (or cotton swab with alcohol) and then wipe the electrical contacts of both your camera and lens. It might make it significantly better.

and putting the camera on AF-S will help too. Learning how to manually focus will fix the problem too... period.

And putting the camera on center point when you want the center to be in focus will make it faster/accurate.

If you are a true PROFESSIONAL like you say you are, you should know this by now. User error happens but don't be ignorant about it...


Last edited by GLXLR; 08-17-2009 at 08:54 AM.
08-17-2009, 10:00 AM   #9
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I do remember that "rubbish" thread. And that's why I am once again assuming it's operator error until demonstrated otherwise.
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