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Old Mar 2, 2006, 12:11 PM   #11
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As a new owner of a *istDL, I was having a simialr problem and returned the camera to Pentax for service. They realligned and recallibrated the focusing mechanism and things have now improved.
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Old Mar 2, 2006, 12:27 PM   #12
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RiceHigh wrote:
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I have another thought. Isn' t that at very shallow DoF, the AF system should be able to distinguish difference better and easier?
Sure, the AF system should be able to distnquish better. I'm just pointiing out that problems from user error tend to increase in those conditions.

If I shoot at wide open apertures and closer ranges, I try not to reframe after locking focus (because DOF is so shallow it can increase you number of OOF photos with very little camera movement required).

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Old Mar 2, 2006, 2:34 PM   #13
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With "any" movement using a shallow DOF lens like my 85 1.4 wide open the focus will appear to be off since the DOF is less than an half an inch in a normal portrait setting.

That means camera movement and subject movement!

In normal use shooting wildlife, my AF in my DS is always right on and the images are never out of focus unless there is pilot error on my part.

Tom


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Old Mar 2, 2006, 5:26 PM   #14
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ennacac wrote:
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With "any" movement using a shallow DOF lens like my 85 1.4 wide open the focus will appear to be off since the DOF is less than an half an inch in a normal portrait setting.

That means camera movement and subject movement!
Exactly.

Now, that doesn't mean that AF systems can't be out of calibration (you see AF calibration problems from cameras made by all of the major manufacturers from time to time). Af sensor alignment, mirror alignment, and even software calibration come into the equation. QC isn't what it used to be.

But, a lot of the time, it's not the camera's fault when you get OOF images (it's user error more often than not).


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Old Mar 7, 2006, 8:06 PM   #15
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Hi all,

I've got a chance to try Pentax SMC DA 50-200/F4-5,6 lense and with this lense autofocus was very precise. No hint of backfocus at all, I was shooting at 50mm. Then I tried to shoot in exactly the same conditions with my SMC DA 16-45/F4, mainly at 45mm and most of pictures were with backfocus.

So I make a decision that my 16-45/F4 is faulty...

Now "fun" with Pentax warranty starts... :sad:

--
Edvinas
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