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09-30-2014, 09:39 AM   #16
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Ideally, you'd be able to look at photos and tell whether a lens is performing well. Then if there's a problem, focus adjustment is one tool to fix it. In the real world, that skill doesn't just appear by itself. How do you spot defects with limited experience with a new lens and camera? I know I was fooled by a lens that focused quite well, up to the first mile or so. So the focus adjustment process can be a learning experience. It may not fix anything but you learn something about careful focus and your lens.

09-30-2014, 11:17 AM   #17
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I don't do it because 1) I have zero confidence in my ability to do it and not make matters worse, 2) it seems incredibly tedious and 3) I have too many lenses.
09-30-2014, 07:39 PM   #18
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I do it because I have no choice.
09-30-2014, 08:19 PM   #19
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The biggest issue I have seen with focus adjustments is people not understanding that ideal focus is not necessarily centred in the range of acceptable DOF

The tendency is to shift the focus to the wrong place. The other issue is that focus is a range even with the best sensors. Making sure they see the target correctly is not assured on many tests. Lastly I rarely see focus tests where the pattern and measurement is square to the camera.

I agree with most others . It is a real area to screw up If you are certain you have it correct you can try, but I have not seen any need with my lenses. My focus errors are my mistake usually

09-30-2014, 09:16 PM   #20
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QuoteOriginally posted by Undot Quote
So I am wondering if I should go through my lenses to verify they hit the spot on a focusing chart or if the author has a valid point and I shouldn't bother. Is doing focus adjustments a bit like pixel peeping, or is it actually founded? What's the chance, that a lens was actually delivered out of focus?
After the second major outing (family visit) with my Sigma 30, I noticed all the shots were back-focused just a tad. So, I shot a crack filled with grass in the sidewalk from about 5 feet away at f1.4. Took a few shots. I ended up dialing in +5 on one body, and later, +1 on another body. I'm guessing at farther distances any error is less noticeable. Keep checking your shots on occasion. If they consistently look off, then adjust. That is what the feature is for, after all.
10-01-2014, 08:56 AM   #21
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After I got my new-to-me FA 20-35 lens, I was disappointed that it never seemed to give me a satisfying image. The lack of sharpness of the subject was obvious, and the background was always more in focus. Hmm, that'd be back-focusing. So I set up a test run, on a tripod, with a fence as subject, lawn as foreground, and trees as background. The images got better (focusing on the desired subject) as I cranked from 0 up to +10 adjustment. I felt fortunate that the +10 adjustment turned out to be accurately focused, as that was the adjustment limit for my K-5.

Now my FA 20-35 is working up to expectations, and is a favorite. It fights for camera-mount time with my FA 24-90, which required a setting of +8. None of my other AF lenses have required obvious adjustment, so I've made no adjustment runs on them. But, of course, I have checked that they do focus accurately.

So my suggestion would be to make an adjustment run on a lens only if it clearly shows a consistent focus problem. Make sure any adjustment run is set up to make the actual plane of focus very clear. A Lens Align rig should do the job. I just use my outdoor setup with background, subject, and foreground objects that are clearly separated from each other. That's accurate enough for my work.

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