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Old Jan 2, 2010, 2:31 PM   #1
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Default focus adjusting

I'm going to try this again. I had done it a while ago, but wasn't sure I did it 100% correctly. I've since set the camera back to default on all the lenses.

When I do the test with a zoom lens, do I set the lens at smallest zoom, largest zoom or in between?

Thanks, Patty
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Old Jan 2, 2010, 3:36 PM   #2
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I set it at the largest zoom.
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Old Jan 2, 2010, 8:55 PM   #3
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Thanks, BD. I'll work on that tomorrow.

Patty
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Old Jan 2, 2010, 9:57 PM   #4
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I take pictures at widest, longest and mid range, then see if they all show focus problems. I think I've finally figured out what's going on with my 12-24 - it's front focusing quite a bit. I took several pictures at various focal length and they all show it. I was actually quite impressed with how much adjustment there is. It seemed though that it's in between adjustment points - one still shows some ff while the next adjustment point seems to show a bit of back focus. I figure I'll leave it on one and take a bunch of real-world pictures with it, then decide if I've got the problem fixed or want to go back one number.

To make sure that I was getting good results (I was using a focus chart that I wasn't sure would work the way it is supposed to), I also shot some pictures with the 50-135. I've always thought the lens slightly backfocused, but it wasn't really enough to bother with. The chart did show the slight bf, so I adjusted that lens, too. It's easier to see the focus point and what's going on with a small dof - the 12-24 was way off so easy to see in the beginning, but harder to judge when I got close. I figure it won't matter as much, since it does have such a large dof.
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Old Jan 3, 2010, 10:31 AM   #5
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Hmmm... I wonder if that's why my 12-24 seems so soft to me? I guess I'll have to check it out. Thanks Harriet.
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Old Jan 3, 2010, 4:19 PM   #6
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My 12-24 had never reliably focused to infinity - it would say it had focus when the lens wasn't set at infinity. It didn't occur to me that the problem was with the focus until I took some pictures of my family at Christmas. It was obvious from them that it was front focusing, so I resorted to shooting focus charts. Sure enough, the front focus was such that I didn't imagine that the camera would be able to compensate - I've never felt a need to mess with the focus adjustment before and assumed it would only adjust a little bit. I was impressed because I'm about at the middle of the adjustment scale, and I may have gone too far. The 50-135 was only slightly back-focusing and I only adjusted it by one.

I ended up using this focus chart: http://regex.info/blog/photo-tech/focus-chart . I took his suggestion and printed it on heavy paper so it lies flat, and chose the one at 10% version, worked fine (the camera really wasn't capable of focusing on the grey lines, not enough contrast).
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Old Jan 6, 2010, 7:12 PM   #7
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GW - did you do anything about your 12-24? I did 3 things this weekend - I adjusted the focus so now it'll focus at infinity. I thought the distance pictures still looked softer than they should when viewed on the monitor, so I looked closer at the lens - the front element was covered with dust. Dealt with that but before I used it again, I read about a new firmware release. It's just another version of the current release, but someone on another board thought it helped with the SR at higher shutter speeds. I had been thinking what I was seeing was more like camera shake, but at 1/1600 sec shutter speed - I shouldn't have had any. I figured the worst that would happen would be that I'd be re-installing the same firmware update, so I downloaded the file and installed it. Yesterday I tested it around a parking lot and was really, really impressed. I had liked it when I first got it but have been unhappy with it since getting the K-7. I don't know if it was the software or the dust removal (the dust was significant) in addition to correcting the front focus, but now I'm REALLY happy with it. It's like getting a whole new lens again.
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Old Jan 6, 2010, 9:21 PM   #8
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Quote:
Originally Posted by mtngal View Post
GW - did you do anything about your 12-24? I did 3 things this weekend - I adjusted the focus so now it'll focus at infinity. I thought the distance pictures still looked softer than they should when viewed on the monitor, so I looked closer at the lens - the front element was covered with dust. Dealt with that but before I used it again, I read about a new firmware release. It's just another version of the current release, but someone on another board thought it helped with the SR at higher shutter speeds. I had been thinking what I was seeing was more like camera shake, but at 1/1600 sec shutter speed - I shouldn't have had any. I figured the worst that would happen would be that I'd be re-installing the same firmware update, so I downloaded the file and installed it. Yesterday I tested it around a parking lot and was really, really impressed. I had liked it when I first got it but have been unhappy with it since getting the K-7. I don't know if it was the software or the dust removal (the dust was significant) in addition to correcting the front focus, but now I'm REALLY happy with it. It's like getting a whole new lens again.
Hey Harriet,
No, I haven't been feeling to well this week and haven't done much of anything. I do recall up-dating my firmware a couple months ago and it was suppose to have something to do with the SR but I haven't done any comparison shots so, I don't know if its any help or not, not sure if that's the same up date you're referring to or not. I'll check it out, can't hurt anything... Glad yours is doing better!
Thanks for the heads up.
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Old Jan 6, 2010, 11:54 PM   #9
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I had upgraded to 1.02 fairly recently, and there's nothing in this new file that I saw that indicated it was any different than the version that I had previously installed. But there are those who can say it is different and refer to a number they can read though a different program. I can't say that it was what made the difference, or just brushing off the dust but as far as I'm concerned, it doesn't matter. I'm just a happier camper.

Hope you feel better - I know people with an ugly cold that comes back just as they think they are over it. Hope that's not what you have.
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