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PostPosted: Sun Jul 15, 2012 4:37 am 
Ok Thomas, that's what i will do know. I just thought it might be nice for some to view the whole uncompressed image at 100%.
I cropped the images with Adobe Bridge at 989x659 resolution.
http://www.flickr.com/photos/22285064@N ... 580733610/


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PostPosted: Sun Jul 15, 2012 9:39 pm 
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Aha, this material is better to work with. Black on white delivers a much better contrast to judge and small letters are a very good target :!:
Left top corner looks better than right bottom, BUT: this is because the right top corner of the left top corner looks really good - if you know what I mean :mrgreen:
If you look in the left top corner of the image from the left top corner it does not look clearly better than the right bottom corner of the image from the right bottom corner...
So methinks this is a draw

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PostPosted: Tue Jul 17, 2012 3:03 pm 
The corner of the corner is better than the corner :D How do you think my lens compares with yours? And since you are experienced photographer having tried out many lenses, do you think I should keep it or return it? I don't mind spending +400$ for the Canon 24-70 ver 1 but I read it is inferior.
I also posted the sample images in the photozone forum, Klaus says he can see some decentering on the quadrant test, but then he says no lens is perfect... Answers a question with a question.
What do you think? I have 1 more week to fiddle around with the lens until the 14 day return period is over. Let me know please.. Thanks


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PostPosted: Tue Jul 17, 2012 6:22 pm 
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My bitter experience with decentered lenses (lastly this Tamron and then the Nikon 24-120/4.0G VR) taught me one thing:
Decentering is easy to overlook in everyday shooting situations because you have to be very clear/exact where your plane of sharpest focus should be in an image. This was the reason I didn't immediately notice the decentering in those two lenses because I was happily shooting street scenes and nature-pics.
The best bet to see decentering clearly is with a shot from a considerable distance wide open (naturally) and mostly at the long end of a zoom. And with "considerable distance I mean a distance of >1000 x focal-length. So with a 24-70mm lens get away some 70-100m from (a) either a straight row of buildings or (b) a straight row of trees a long a street. Try to shoot pretty perpendicular to the row although at that distance it is not too critical. Keep the camera tilted to the left so that the row goes from one corner to the opposite corner in the viewfinder, focus on the subject (house, tree) in the middle and shoot (with a short enough shutter to avoid shake at all cost, or even better from a tripod). Now tilt the camera to the right so that the row goes through the other two corners and shoot again. If the difference in performance in the left corner and the right corner bothers you: send the lens back.
(Note: you may keep the camera level and just do one shot to compare the left border against the right border, but the dual-shot-tilted method is safer).

Have a look at the following image in full resolution:

Image
Tamron 24-70f2.8 VC @70f2.8 54685 by Thomas, on Flickr

and compare the resolution in the foliage on the left side against the right side. This is what I'd call a clearly visible difference.
There's only one caveat: this image was captured with a 36MP FF/FX-sensor - f you use a 18MP sensor differences might not be so clear.

Main message of this lengthy post: shoot, shoot, shoot. And if you're not satisfied, return the lens. No-one else can make the decision for you.

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PostPosted: Wed Jul 18, 2012 2:16 am 
Thomas, why are you showing me this cell phone image? :D Really, the whole image is terrible, not just the corner. What did you do to scare off the resolving power of the lens? Is this the case with all your lenses or it's just the Tamron performing extremely bad, or it's just the over demanding d800? :?

P.S. In real life it might not be a problem as you said, but I will always know there is a problem. It's like wearing a watch with a scratched back cap. You can't see it but you know it is there...
Sending the lens back today for a replacement, HOPEFULLY the new sample will be better, otherwise I am crossing Tamron off the list.
P.S.S
I just did the same newspaper test with the 18-55 IS Canon on my 450d
The result is HAHAHAHA :D
Day and night = tamron 24-70 vs canon 18-55
I thought that it is very bad, but once i stick the kit lens image in my pc i think I was expecting too much from each lens...
I wonder how some peoples images look extremely sharp even at full camera resolution. Is it the post processing or it is the lens...


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PostPosted: Sat Aug 04, 2012 2:42 pm 
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The new copy of the Tamropn 24-70/2.8 VC has arrived and seems to be well centered as first test-shots confirmed. But I discovered another "bug" with the new lens :(
Have a look at my following test-series:

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Aperture-precision by Thomas, on Flickr

Series of test-shots of a blank target with Nikon AF-S 24-70/2.8G (upper row) vs. Tamron 24-70/2.8VC (2nd row) from f2.8 (left) to f16 (right). Crops form the middle of the image to avoid any influence from vignetting. Identical white-balance and supposedly identical exposure.
The Tamron exposes +1EV (!) brighter when stopping down from f2.8 to f4.0 and then gradually becomes darker again.
The Nikon exposes pretty constant over the aperture-series within 1/4EV.

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PostPosted: Sun Aug 05, 2012 5:26 am 
Bugger. I see why professional photographers never use Tamron or any other generic brand lenses.
I returned mine a few days ago. I also sold my 5dm2 and some other Canon lenses. Besides the Tamron being crap of a lens, Canon is driving me crazy with 100 ISO noise in the shadows... I always need to overexpose for the shadow area to be well lit, then recover detail in the highlights with post processing. I will be migrating to Nikon soon, just gonna wait a few more weeks in case they come out with the 1500$ (D600)FF camera, if not i will buy the D800. I need some pro lenses too, like the 70-200 2.8 and some wide angle like the 24-70. I will have a look at your webpage to see which lenses you recommend.


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PostPosted: Wed Aug 29, 2012 9:25 pm 
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Now here's my full review. Gordon just published it.
Hope you enjoy it!

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