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Old Feb 14, 2014, 6:38 PM   #1
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Default wide angle, widest aperture, distant focus, sharpness expected?

Just got a Tokina 11-16mm f/2.8 AT-X116 Pro DX for my t3i.

I know, generally shooting wide open makes pictures soft. But should I expect CENTER sharpness when focused to infinity + wide open for any wide angle lens?

At 11mm f/2.8 infinity, center focus point, the center is a bit blurry. I am standing 30 feet away from the dark green tree. See crop... http://farm6.staticflickr.com/5498/1...c012c69a_o.jpg

at f/4.5 infinity, it's noticeably better. see... http://farm3.staticflickr.com/2832/1...96543541_o.jpg

Is this normal for wide lenses?

at f/2.8 up close, the center is sharp enough as expected..... http://farm6.staticflickr.com/5521/1...a9342ec4_o.jpg

Is wide open aperture absolutely unusable when shooting an object over 10 feet away, if you want some sharpness?
or is f/2.8 only for close objects?

Last edited by makeitwide; Feb 14, 2014 at 6:41 PM.
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Old Feb 14, 2014, 7:02 PM   #2
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It doesn't look like your first image is in focus at all...

Is the camera in autofocus mode or is it on manual?
When the lens is set to infinity manually the lens actually overshot the distance scale a bit (mainly for IR with different wavelength shooting)
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Old Feb 14, 2014, 7:37 PM   #3
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At a focal length of 11mm, and aperture of f/2.8, and a subject distance of 30 feet, (on an APS-C body) the depth of field is from 6 feet to infinity. As a result, focus error can't be the problem. According to PhotoZone.De, the Tokina AF 11-16mm f/2.8 AT-X Pro DX is sharpest from f/4 to f/8.

I would just attribute your results to the lens' softness wide open, which is not uncommon with lenses of any kind and from any manufacturer.
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Old Feb 15, 2014, 12:16 AM   #4
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I just took another picture, infinity focus-
f/2.8- http://farm3.staticflickr.com/2842/1...1e49acf0_o.jpg
f/8 - http://farm4.staticflickr.com/3832/1...9422dfa0_o.jpg


f/8 is a lot sharper, as expected.


All the reviews said that the tokina was sharp in the center, even at f/2.8.
Does that include infinity?

For me, seems like f/2.8 is focused in some places but the center. The ground 6 feet away looks pretty sharp, and so do the side edges.
Makes me wonder if the lens is misaligned.

But looking at the f/8 photo..... rules out misalignment and focus issues?
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Old Feb 15, 2014, 8:19 AM   #5
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The Tokina is sharp at f/2.8 in the center. It's just sharper when you stop down, as is the case with most lenses.

BTW, past f/8, images start getting less sharp, as is also the case with most lenses. PhotoZone.De published its review of the Tokina AF 11-16mm f/2.8 AT-X Pro DX (Canon) here, but the actual measurements are on the second page (Analysis). There, you'll see their test results for Distortion, Vignetting, MTF (resolution), and Chromatic Aberrations (CAs). Considering their test results for vignetting, I'd avoid using that lens at f/2.8 anyway, unless I really needed the extra light for shooting indoors or at night.

I think your lens is performing as expected, which is to say, as good or better than other lenses of its type.
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Old Feb 15, 2014, 8:35 AM   #6
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I actually wanted to buy this lens, but looking at the images you've posted, I'm kinda hesitant now.

I see so much chromatic aberration, even at f/8.
Wide-open, there's a very abrupt drop in sharpness in the corners. They look almost blurry.

And in all the images, the portion of the grass in front of you, 6ft as you said, seems more in focus/sharper than the rest of the image.

For a lens with only 1.5x zoom ratio, it doesn't perform that well, IMO.

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I'd avoid using that lens at f/2.8 anyway
OK, but in that case what's the point of having a 2.8 lens anymore?
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Old Feb 15, 2014, 9:41 AM   #7
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Quote:
Originally Posted by Marawder View Post
I actually wanted to buy this lens, but looking at the images you've posted, I'm kinda hesitant now.

I see so much chromatic aberration, even at f/8.
Wide-open, there's a very abrupt drop in sharpness in the corners. They look almost blurry.

And in all the images, the portion of the grass in front of you, 6ft as you said, seems more in focus/sharper than the rest of the image.

For a lens with only 1.5x zoom ratio, it doesn't perform that well, IMO.
Short focal length lenses must bend light a lot more than longer focal length lenses, and not bending light exactly right is want causes chromatic aberration:



The Tokina 11-16 may not be a great lens, and it does seem to have more than its fair share of CA, but there aren't a lot of lenses that are very much better, especially in that price range.

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Quote:
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I'd avoid using that lens at f/2.8 anyway
OK, but in that case what's the point of having a 2.8 lens anymore?
Lenses with a maximum aperture of f/2.8 are generally sharper at f/4 than lenses with a maximum aperture of f/4 are.

... and you've got the f/2.8 when nothing else will do.

If you can afford to use a slower shutter speed in order to stop down a bit, where's the harm. That's generally a good idea with any lens, btw.

Notice that I said "avoid using" not "never use".
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Old Feb 15, 2014, 10:48 AM   #8
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One of the things photographers do to try to get better photographs is explore the limits of their gear. You stumbled on a weakness. Now you know how to avoid it, or exploit it should the opportunity present itself.

Very few lenses are perfect, few of them are wide angle lenses, most of them are primes, and most of them are expensive. You've got a pretty good ultrawide angle zoom lens that didn't cost you much, comparatively speaking.
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Old Feb 15, 2014, 2:27 PM   #9
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Depth of Field Table
I would try the same shot at each f stop to find out where your sweet spots is for this lens.

Last edited by rainrunner; Feb 15, 2014 at 3:04 PM.
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Old Feb 16, 2014, 2:37 AM   #10
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Quote:
Originally Posted by NHL View Post
Is the camera in autofocus mode or is it on manual?
When the lens is set to infinity manually the lens actually overshot the distance scale a bit (mainly for IR with different wavelength shooting)
I tried both AF and manual. In manual, I used Live View 10x zoom to make sure I had the sharpest focus. At f/2.8, that was the best it could do.



Quote:
Originally Posted by Marawder View Post
I see so much chromatic aberration, .....

OK, but in that case what's the point of having a 2.8 lens anymore?
I expected the CA, and I have photoshop to fix it. I read that it's a characteristic of most wide angle lenses. The kit lens is only a little better with CA, but still can't avoid CA in outdoor sunny photo.

After playing around with it, the 2.8 is best for shots less than 10ft where you want to get some bokeh (though I read this lens doesn't give pretty bokeh, as this next photo shows...)

Here's a close up at 11mm f/2.8, center focus... http://farm4.staticflickr.com/3682/1...7ba5358f_o.jpg

I wouldn't give up on the lens. I may be expecting too much at 11mm for hyperfocus, and it may actually be performing normally. Looking at the pixel peepers website, the sample images with distant focus are not tack sharp either.

At 16mm, distant objects are pretty sharp in the center at f/2.8 compared to kit lens.
Here are some shots compared to the kit lens, both from same tripod position, of a house 100ft away, cropped down to center focus area, no resize, not sharpened, level 11 max quality compression-
Tokina 16mm f/2.8 ..... http://farm6.staticflickr.com/5478/1...8d697772_o.jpg
Kit lens 18mm f/5.6 ..... http://farm4.staticflickr.com/3746/1...8b0d0efd_o.jpg

Quote:
Originally Posted by rainrunner View Post
I would try the same shot at each f stop to find out where your sweet spots is for this lens.
I already know the sweet spot. it's f/8 for edge to edge sharpness. Anything over that gets blurry again.
f/5.6 is decent too, but a little soft towards the left and right edges.
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