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02-22-2008, 05:14 PM   #1
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DA* 16-50mm Sharpness Sample?

What do you guys think about this copy? Sharp or not? I just want to make sure, with a group consensus, before I spend a significant chunk of change.

16mm f2.8

50mm f2.8

02-22-2008, 05:17 PM   #2
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Kinda hard for me to tell from those pictures, kinda playing with my eyes, but it looks good enough I spose. I did notice the vignetting though...
02-22-2008, 05:21 PM   #3
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It seems to be sharper than most I've seen. I agree with Buddha Jones that there is some vignetting.
02-22-2008, 05:30 PM   #4
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The far left side looks out of focus to me in the second picture. Actually the right isn't looking to hot there either.

02-22-2008, 05:37 PM   #5
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There is noticeable light falloff at the corners and barrel distortion at the wide end. A little soft at the corners but it is acceptable in my opinion.

I guess the next debatable question is whether buying a fast f/2.8 zoom is worth the above optical compromises. Perhaps f/2.8 isn't as great as fast lens advocates make it out to be.
02-22-2008, 05:46 PM   #6
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Top pic has a fair bit of barrel distortion and some vignetting. Both pics display soft focus toward the edges. You decide if this is acceptable for an expensive DA* lens.
02-22-2008, 06:45 PM   #7
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Good points all around. How close were you to this wall?
02-22-2008, 10:19 PM   #8
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QuoteOriginally posted by Buddha Jones Quote
Good points all around. How close were you to this wall?
Exactly...either those are very large bricks or you were very close. Its not really fair to judge the edge and corner sharpness of the lens from a picture taken at f2.8 from very close range. The distance from the lens to the corners and edges is much greater than the distance to the center (on which you were focused). Either stop down or even better...move back.

02-23-2008, 01:13 AM   #9
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New sample @ 50mm f2.8

02-23-2008, 02:44 AM   #10
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If you have no focus chart, place a pencil next to a ruler and focus on the pencil.
Use a tripod.
Then check the image if the ruler is sharpest next to the pencil.
Repeat for 16mm f2.8 and 50mm f2.8.

Then test this:
Focus at 50mm and then zoom back to 16mm and take the picture.
Compare it to one focussed directly at 16mm.
The first is allowed to be slightly better, but not very much.

At last test this:
Focus on a far away tree or tower (infinity).
Place the tower in the middle of the image.
Then place it in all four corners.
Compare the images.
All the corners should show about the same sharpness.

If these tests come out ok, keep the lens.

02-23-2008, 03:24 AM   #11
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Wieland's test suggestions are pretty good. But remember that zoom lenses, even modern, high-end ones like the DA* 16-50mm, are rarely as sharp at their focal length extremes as they are just a few millimeters in from those extremes. For comparison's sake, also try shots made at the maximum MTF aperture, usually around f/8. Sharpness is rarely optimal at full open aperture, after all, especially at very close focusing distances where there is a meaningful difference in the distance light travels to the sensor plane between the corners of a lens and its center.

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