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Old Jan 4, 2006, 5:00 PM   #21
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MagicMatt,

from one of my previous posts: "...I did not realize the camera was malfunctioning ALL ALONG (very 'soft focus' images). I just thought it was the 'digital thing with dslr' and that it was customary to have major PP issues"

i was not really happy with the camera from the beginning but was getting 'acceptably' sharp images which i could make excellent by PP

i only saw the real severity of the problem when i used a 50mm at f1.7 at 12-15' range to shoot x-mas lights (an excellent test BTW)

it had been very 'soft' from day one, but not bad enough to return

now that it has been calibrated (i locked the 3 screws w/ nail polish as insurance) it takes razor sharp printable shots OOC

lol, john



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Old Jan 4, 2006, 5:26 PM   #22
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bernabeu wrote:
Quote:
i only saw the real severity of the problem when i used a 50mm at f1.7 at 12-15' range to shoot x-mas lights (an excellent test BTW)
I might disagree with you on that one (christmas tree lights making an excellent test).

For whatever reason, Christmas tree lights tend to "fool" a lot of AF systems (just like a reflective surface can).

Also, the "glow" or "halo" (for lack of a more technical terms) of the lamps can make it appear like you've got a focus issue, when it's usually more of an exposure issue with digital, probably due to saturation of photosites from the lamps while trying to get proper exposure for the darker areas in the image (with the halo surrounding the lamps making them look "fuzzy"/out of focus).

Using a bit of fill flash (trying not to use too much so that the lamps are still visible) helps out with the "halo" issue (but, not necessarily the AF issue, depending on the DOF of the camera being used). You see the same issues shooting christmas tree lights with pont and shoot models that have super Depth of Field.

IOW, a lit up christmas tree would be about the last subject I'd personally use to test Autofocus. I've seen too many photos from too many different cameras, with users complaining about AF when shooting Christmas Trees (when otherwise, their AF system worked fine). ;-)

I'm not doubting you had an AF calibration issue. Depending on the severity of the problem, most users would probably never notice it unless shooting at wider apertures and closer ranges anyway.

But, I wouldn't use a lit up Christmas tree to test for an Autofocus Calibration issue.


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Old Jan 4, 2006, 7:00 PM   #23
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JimC,

I bow to your expertise, but, I am far from an amateur.

I used a yardstick at 45 degree angle from camera and a tripod to actually test the AF after the x-mas light fiasco 'tipped me off' to the problem.

When I said Christmas lights make an excellent testI was 'spot on'.

Focus on an object in the same plane as the lights, compose the scene, squeeze the shutter and you should get nicely circular overexposed lights with everything around them (on the same plane) in focus and slightly underexposed with a nice warm look from the tungsten elements.

I was shooting outdoor light displays in my developement, many of which were flat wall type displays and many of which were also lit with floodlights.

What I got was a circular double halo on ALL my outdoor light display shots and soft fuzzy surrounding elements. (I have satisfactorilly make this kind of shot for 30+ years)

The attachment was made with a s7000 set to f2.8 using AF and I really expected even better from my 7D and 50mm f1.7

(i think i may have a communication issue with you on my part)

lol, happy new year, good shooting !! ................ john



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Old Jan 4, 2006, 7:15 PM   #24
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s3800

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Old Jan 4, 2006, 7:34 PM   #25
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It's obvious that AF was correct for those shots (you can tell by the other objects in the image). Many users misinterpret the soft look of the lights glowing as an AF issue (and I wanted to make sure you weren't judging AF by that part alone). ;-)

Also, some AF systems can be fooled by lights like those on a Christmas Tree. I can remember some discussions a few years back about it on another forum, with users sharing their problems with false focus lock when Christmas tree lights were in the scene (with more than one camera model). Some of these were genuine out of focus subjects versus misinterpreting the soft look of the glowing lights.

One of the cameras exhibiting this behavior (false AF lock, apparently caused by the lights) was a Minolta DiMAGE 7 series model. It could be that some non-DSLR models are more impacted due to reliance on seeing contrast in the image from the CCD for AF, too (although yours seem to be focused properly).

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Old Jan 6, 2006, 11:17 AM   #26
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after minolta AF calibration:

shot @ 200mm f4 and cropped 800%

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Old Jan 6, 2006, 6:10 PM   #27
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Nice shot
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Old Jan 9, 2006, 5:05 PM   #28
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Mines going into KM this week, KM seam to be fully aware of the problem and didnt seam at all supprised when I called them about it.

Im looking forward to taking sharp photos because it's really starting to bug me now.
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Old Jan 9, 2006, 6:36 PM   #29
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Radweld,

after minolta calibrated the AF (in my case pitch and yaw 3/2)

this was asnapshot[AF reflex 500mm f8]taken in RAW + jpeg straight from camera except crop and frame


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Old Jan 10, 2006, 1:44 AM   #30
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Focus is good, but the bokeh from that lens makes me dizzy:?
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