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08-19-2014, 04:26 PM   #1
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Newbie to K3 question on manual lens focusing

My first few days out with the K3 have bee interesting and challenging. I have had a K5ii for a while now but the K3 has a learning curve. I have bee having problems trying to get good focus to infinity on my non Da lenses, a 100 mm M series and in particular my 200 mm K series. When faced with high contrast long distance shots the K3 exhibits blue fringing, the k5ii green in the same shot.

I am coming to a horrible conclusion that either I have some setting wrong (that would be good if I can find it) and the other is these primes are not going to make the cut quality wise to keep up with the images from by DA 50 and 35 mm.

I am willing to go through this learning curves but the manual with the K 3 makes an assumption you already know a lot about their stuff. ITs half the size of the K5ii manual. I had to buy Yvons ebook just to figure some basic stuff out. Anyway that's up to Pentax I guess.

I am looking at jpg files on my iPad and the firmware needs upgrading so I am hoping that is some of the fringing problem but does not explain the infinity focus. ( don't have access to my computer to do the firmware upgrade from here). All the focus settings are giving me confirmation I am in focus both through the viewfinder and in Live view with focus peaking on.

Any thoughts and ideas would help sorry can't post pics from where I am located.

08-19-2014, 04:52 PM   #2
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Sounds like you are asking two different questions.

First, purple or green fringing is a product of the lens not the camera. Film era lenses almost all (to my knowledge) exhibit at least some of this when used on digital. It is more noticeable in high contrast situations. Firmware should be updated, but that is not going to make any change to the fringing.

Next, not good focus at infinity. Not exactly sure what is the problem. Do you mean you get good focus on the k-5ii but not on the k-3? There is quite a bit of slop in focus confirmation light so relying on that might or might not get you good focus.
08-19-2014, 05:12 PM   #3
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Manual focus works the same on your K-3 as on the K5-series cameras with one exception. On the K-3 you have focus peaking in live view. Using the AF system for focus confirm should be somewhat more dependable with the K-3 and faster lenses (f/2.8 and wider) and about the same with slower lenses.

The color artifacts you are seeing are not related to focus accuracy:
  • Purple/blue fringing may be due to longitudinal chromatic aberration which is a lens characteristic and present regardless of the camera used. It may also be the hard-to-characterize "purple fringing" that is an artifact of digital capture that is triggered by some lenses.
  • A greenish border is lateral chromatic aberration and is also a lens characteristic.

All that being said, you may indeed be having problems managing manual focus on your K-3. Missed focus is incredibly easy to see on the high resolution K-3 image. So is inherent softness. I do not have hands-on experience with either of your lenses, but I don't believe that either has a reputation for softness. I would expect that both would perform at least as well on your K-3 as on the K-5II.*


Steve

* For an equivalent size final image

Last edited by stevebrot; 08-19-2014 at 05:17 PM.
08-19-2014, 05:19 PM   #4
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QuoteOriginally posted by jatrax Quote
Sounds like you are asking two different questions.

First, purple or green fringing is a product of the lens not the camera. Film era lenses almost all (to my knowledge) exhibit at least some of this when used on digital. It is more noticeable in high contrast situations. Firmware should be updated, but that is not going to make any change to the fringing.

Next, not good focus at infinity. Not exactly sure what is the problem. Do you mean you get good focus on the k-5ii but not on the k-3? There is quite a bit of slop in focus confirmation light so relying on that might or might not get you good focus.
Yes, perhaps this particular subject brought the issue to my attention. The focus problem is perhaps better described as softness for image detail in the DOF area around the target area and infinity. THe shots are not all set at infinity, but close too. Both the K5ii and the K3 Produce good shots with DA primes.

---------- Post added 08-19-14 at 08:26 PM ----------

QuoteOriginally posted by stevebrot Quote
Manual focus works the same on your K-3 as on the K5-series cameras with one exception. On the K-3 you have focus peaking in live view. Using the AF system for focus confirm should be somewhat more dependable with the K-3 and faster lenses (f/2.8 and wider) and about the same with slower lenses.

The color artifacts you are seeing are not related to focus accuracy:
  • Purple/blue fringing may be due to longitudinal chromatic aberration which is a lens characteristic and present regardless of the camera used. It may also be the hard-to-characterize "purple fringing" that is an artifact of digital capture that is triggered by some lenses.
  • A greenish border is lateral chromatic aberration and is also a lens characteristic.

All that being said, you may indeed be having problems managing manual focus on your K-3. Missed focus is incredibly easy to see on the high resolution K-3 image. So is inherent softness. I do not have hands-on experience with either of your lenses, but I don't believe that either has a reputation for softness. I would expect that both would perform at least as well on your K-3 as on the K-5II.*


Steve

* For an equivalent size final image
Thanks. Having tested the lens (200 mm) on both cameras it does seem like the image is soft, i am confident the targets in the image were in focus on the lens. Both lenses produced similar results except for color of the fringing.

A close focus example with the same lens this eve nine is very sharp.

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