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06-22-2012, 12:00 PM   #1
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Focusing problem

Hello!

I'm a little bit confused about a thing that happened to me regarding focusing. I've just bought the DA*55 and trying it I saw that it wasn't as sharp as it should.

I also know that some lenses need the Adjustment of the AF and so I didn't worry so much.
BUT the problem, or better, what I don't understand, is that when i'm in Live View mode and I shoot, pics are sharper then pics I take through the viewfinder.

So my qyestion is: WHY? Is normal? Or does it depend on the how the camera focus (I think, at this point, that there are different ways)?

Thank you for your help!
Gabriel

06-22-2012, 12:18 PM   #2
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Live view is default using CONTRAST detection autofocus.

Your Optical Viewfinder view is using Phase detection. You can adjust the Phase detection, but can't adjust the contrast detection because it measures contrast.

Contrast is slow but ACCURATE, but Phase is slightly faster.
06-22-2012, 12:21 PM   #3
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I am sure someone will reply with a more technical answer but briefly:
Your camera has three different focusing methods.
1) Through the view finder auto focus using phase detection
2) Live View auto focus using contrast detection
3) Manual focus using the focusing screen and view finder

Ideally all three methods would agree and whenever I get a new lens I test with all three methods until I get them to agree.

You do not mention which camera you have. The k-5 (and I believe the k-20 and k-7) has the ability to adjust focus on a individual lens basis, I think 20 different lenses can be stored, but not sure. The k-x and k-r have the ability to adjust focus but it is a global setting so all lenses are affected.

Manual focusing can be adjusted by shimming the focus screen if needed but again that is a global adjustment and not something to be done lightly. I assume this is correct and is the basis for adjusting the AF system.

Assuming you have the k-5 then you should test the new lens and adjust the focusing in the menu, I think it is called Autofocus fine adjustment.

However, test thoroughly first before making any adjustments. There are a number of things that can cause an out of focus image that have nothing to do with the autofocus system and starting in to adjust it can make things worse rather than better. Use a tripod, and fixed focusing target. Repeat the test numerous times to be sure the results are consistent. Make the test with all three systems and compare the results.
06-22-2012, 12:32 PM   #4
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Thank you both for the answer! And thank you also because I've learned a thing that I didn't know (the different ways to focusing used by the camera)!!

Yes I've a K5 and I know that there is the AF fine adjustment. What I don't know is that is normal this difference between focusing through the viewfiner and the live view (now I understand that there is).
Now another thing that i ask you is: if I adjust the " AF fine adjustment" on what I see in the viewfinder, will the live view focus be affected too by those adjustmens or it's independent?

Thank you

06-22-2012, 12:50 PM   #5
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QuoteOriginally posted by gabro822 Quote
will the live view focus be affected too by those adjustments or it's independent?
Live View is separate and not affected by the adjustments. So use it as a guide as you tune the phase detect. As noted above it is quite accurate but not as fast.

And please test thoroughly first! Just making changes based on casual observation without controlled testing is likely to make things worse not better! There are many threads here about how to test a lens for AF accuracy. Just do a search of the forums and you will find lots of information on how to test.
06-22-2012, 12:54 PM   #6
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Ok thank you very much!!
Now I will try to see if I can find the thread where is explained how to test thoroughly the lens!
Thank you!!
06-22-2012, 01:14 PM   #7
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Sorry, I reconnect to this thread to ask you a thing about AF tune.
There are lots of topics in which people ask what is it, but noone who explain how to do it, step by step.
Do you have any suggestion? Sites? Threads that I didn't see? And above all, as said by jatrax, how can I verify if my lens need an adjustment?

thank you!
Gabriel
06-22-2012, 06:37 PM   #8
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Try this site ----->here

I used this in the past. It is easy to set up. I echo the sentiments of the others to really be sure that you truly have an issue prior to making changes in the AF adjustment.

Good Luck,

Mark

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