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03-12-2009, 11:28 AM   #16
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Focus test charts have been the source of some major stress and head scratching for me. I wish I never would have printed one. Some how all my sigma lenses are off and require -5 to -10 adjustment....and that is after I had Pentax check my camera's focus under warranty. My FA50mm requres -10 as well. Oh well. I still love my K20D. : )

03-12-2009, 12:23 PM   #17
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QuoteOriginally posted by AV82GOLF Quote
I recently ran into this same problem while trying to adjust my various lenses to my K20. I just had my K20 returned from Pentax for servicing because I couldn't bring my DA 40 into focus. Pentax adjusted the focus range and I was in the process of calibrating all of my lenses again when I started noticing the problem. A particular lens would indicate that it needed about a -3 or -4 adjustment. I would make the adjustment, take three shots and compare. One or two of the shots might show an improvment, but the other would indicate that I now needed a + adjustment of +1 or +2! Some lenses were better than others and had no problems, but some just had me chasing my tail. I don't believe that it was operator error as I had the camera on a tripod with shake reduction off and using the 2 second delay while shooting at a perfectly perpendicular test target. Oddly, I would finally give up and try again the next day and the lens would usually come back into adjustment? Not really sure whats going on as I am still in the calibrating process, but it sure looks like the focus is not consistant. The variation is small, and you may not notice the difference on a shot at any distance, but when shooting the test target is is definately noticable.
Ok I had no idea this could be done.. can someone walk me through it? Or should I read the manual
03-12-2009, 12:38 PM   #18
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QuoteOriginally posted by mrt10x Quote
Ok I had no idea this could be done.. can someone walk me through it? Or should I read the manual
Read the manual and then ask questions if you need to. It shows you have a commitment to us having a commitment to helping you.

The Magic Lantern guides are also a worthwhile investment, they cover more ground than the manual.
03-12-2009, 12:44 PM   #19
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QuoteOriginally posted by Damn Brit Quote
Read the manual and then ask questions if you need to. It shows you have a commitment to us having a commitment to helping you.

The Magic Lantern guides are also a worthwhile investment, they cover more ground than the manual.

I have both... just neither on me at the moment... dam you and your practicality

03-12-2009, 01:13 PM   #20
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QuoteOriginally posted by mrt10x Quote
I have both... just neither on me at the moment... dam you and your practicality
LOL, actually I (and a lot of others I bet) am grateful that you considered the manual, we much prefer thinkers than those who ask because it's easier.
03-12-2009, 02:07 PM   #21
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QuoteOriginally posted by StephenMerola Quote
Focus test charts have been the source of some major stress and head scratching for me. I wish I never would have printed one. Some how all my sigma lenses are off and require -5 to -10 adjustment....and that is after I had Pentax check my camera's focus under warranty. My FA50mm requres -10 as well. Oh well. I still love my K20D. : )
I have the same problem with my Sigma 24-135mm lens but in the opposite direction, requires a +7 adjustment. I just picked up a Tamron 70-300mm and after a few test shots today from the parking lot where I work to some buildings in the distance it would seem AF is spot on. I don't know what's up with the Sigma lenses and the K20D. My 24-135mm was sharp as a tack on my *istDL.
03-13-2009, 01:36 PM   #22
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Eventually I sent my k20d back to OZ for a spa treatment.



My first dSLR was a k20d.

The More immediately apparent problems I had with the k20d were around AF issues. Switching to MF was somewhat better. But so dark in there.

I charted and adjusted. I re charted and needed to readjust. After a while, When shooting wide open I danced back and forth until I got better focus. I adjusted and I tried to learn different PP to bring out something interesting in the photos.

Got a refurbished k100d and the difference is night and day. Sharp shots with lenses wide open. I got stuck shooting wide open just to have the pleasure of seeing sharp images. Like getting a new set of lenses.

Took shots rotating lenses in the same lighting conditions. Wow. The k100d was clearly beating the k20d silly. VF much brighter so MF was much more useful. AF somewhat slower but right on. All lenses can focus on target. The limitations of the AF system, as pointed out by others, are there. Still AF is trustable on the k100d while it was at best random on the k20d. Metering better. Flashed like it knew what it was doing with the on board or the pentax 360 (with its silly battery door.) and even noise at high iso was more useful in the k100d. There was something random about it in the k20d.

Occasionally the magic would work out for the k20d and those pictures would be better, have more immediate wow factor.

All at 1/3 the price!

Looking forward to getting my k20d back and having it beat the pants off the k100d in overall performance.

Maybe I'll call it Dorothy and the k100d Toto when It gets back from the Emerald City.

My suggestion? Send it in. That camera is good enough to have clear and present wow factor in most shots even "snap shots". if it is not there then something is up.

Just my $.02!
03-13-2009, 02:37 PM   #23
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QuoteOriginally posted by madmikess Quote
I have the same problem with my Sigma 24-135mm lens but in the opposite direction, requires a +7 adjustment. I just picked up a Tamron 70-300mm and after a few test shots today from the parking lot where I work to some buildings in the distance it would seem AF is spot on. I don't know what's up with the Sigma lenses and the K20D. My 24-135mm was sharp as a tack on my *istDL.

I was just reading in another thread about how tests cannot be done under tungsten lighting because it causes focus errors. If that is the case, then that could definately explain the problems that I have been having. I have achieved some super sharp shots outside, but far less indoors under standard tungsten lighting.

So if you were shooting building outside that could explain things.

03-13-2009, 04:07 PM   #24
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QuoteOriginally posted by StephenMerola Quote
I was just reading in another thread about how tests cannot be done under tungsten lighting because it causes focus errors. If that is the case, then that could definately explain the problems that I have been having. I have achieved some super sharp shots outside, but far less indoors under standard tungsten lighting.

So if you were shooting building outside that could explain things.
Well, with my sigma lens, I first really noticed the back focus problem shooting some subjects at the zoo outside. I made some test shots indoors later and was still seeing the backfocus problem. So I setup the chart to adjust it and was using natural light in the room when I did it. I didn't turn on any lights in the room at all. I was aware of the tungsten light problem and made sure to avoid it. I picked up a Tamron 70-300mm Di LD lens and the AF is spot on with that lens. So it's for sure with just my Sigma lens.
03-13-2009, 05:43 PM   #25
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My focusing issue I mentioned was with the FA 35mm. Well, today I printed out a test focus chart and used it on my Tamron 17-50mm f/2.8. It was backfocusing quite a bit; when I went to adjust the AF, to my shock it was set at -10! After recalibrating, I think it settled on -2 or -3. Anyway, now I need to go make sure that my other lenses aren't adjusted incorrectly.
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