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Old May 25, 2004, 6:20 PM   #1
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I took some comparison shots with this lens, comparing the f-stops.
Camera mounted on tripod.
Autofocus on first frame repeatedly until perfect / best focus achieved.
Then AF turned off and left in manual focus mode to fix that focus.
Camera timer used, so "hands off" shots with the camera absolutely still.
Camera in RAW mode.
F-stops 1.4 through 8 (16 shots).
Pictures processed with CaptureOne to normalize slight exposure variations.
Exact same USM applied to each picture.
Output: high quality JPG to sRGB color space.
Opened each picture and cropped out the clock face.
Re-saved as another high quality JPG (about 500k each).

Results (assuming my web site is up):

My conclusion is this lens has 4 levels of sharpness:
ultra crisp: f8 through f2.5
crisp: f2.2 -f1.8
just OK: f1.6
soft: f1.4
It's possible that the softness at f1.4 is because the camera focused on the hands not the back paper... But that would be an awfully narrow depth of field (1 inch or less).

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Old May 25, 2004, 11:51 PM   #2
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Well, I for one would like to thank you! I certainly appreciate the thoroughness of your tests, and I'm sure it will provide useful insight to users considering this lens.

For the moment, it seems I can't resolve the URLs given. Is it a problem on my end or not? Could you plz double check the addresses, thanks.

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Old May 25, 2004, 11:58 PM   #3
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The site seems to be currently down.. I checked a few times today too so its not just you.
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Old May 26, 2004, 12:30 AM   #4
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My site was down for a few hours... I've been swapping routers & radios lately. It's up right now but it might be flaky, should be stable by Friday.
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Old Jun 22, 2004, 11:08 PM   #5
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What's the math that would tell us what the DOF should be at 1.4 at the distance you were at using the shutter speed you were?

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Old Jun 23, 2004, 12:53 PM   #6
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According to this:


The DOF would be about1/2 inch (2-3 feet from subject).

However, I tried manual focus and couldn't get it any better than the shot I linked above. So I don't think the softness at f1.4 was due to depth of field.

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Old Jun 28, 2004, 5:06 PM   #7
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I LOVE this lens and do a lot of portraits with it. I use it at 1.4 a lot for two reasons, I think it is excellent quality (When you get it right) and it allows me to shoot away indoors with available light, my favourite!!!!!!! This image at full size is awesome and as sharp as you like....money very well spent!!!!


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