Simple Sharpness Evaluation of my Tamron 17-50mm f/2.8


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Nov 16, 2004
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Recently, I was tempted to get myself the Nikon AF-S DX VR 18-200mm f/3.5-5.6 IF-ED and sell my Tamron SP AF 17-50mm f/2.8 XR LD ASPHERICAL [IF], just for the sake of a longer reach and VR. Just when I was pixel-peeping and complaining about the Tamron not being sharp enough for my taste, I started looking up reviews of the Nikon 18-200mm VR with regards to sharpness. I came across reviews commenting on the lack of sharpness of this lens compared to the Nikon AF-S DX Zoom-Nikkor 17-55mm f/2.8G IF-ED but not the Tamron 17-50mm f/2.8. Isisaxon did a good comparison of both Nikon lenses.
I was also discouraged from letting go of my Tamron and save up the money for something else. I decided to give my Tamron lens a chance, a chance to perform. I was bored enough yesterday and did a simple test just by shooting some simple things in my room, to evaluate the sharpness of the lens.

SHARPNESS EVALUATION
(D200, Manual exposure mode, shutter speed 1/60s, L FINE JPEG quality, Customs setting default)
ISO has been adjusted accordingly when a different aperture was used.
All images are cropped at 100% without adjustment in sharpness. Levels were adjusted.
CLICK ON THUMBNAILS TO ENLARGE THE IMAGES (~500kb)



Figure 1. AF area is center. Focal point is neck area.
50mm at f/11


Figure 2. AF area is center. Focal point is the tetra-pack icon.
(a) Left, 50mm at f/2.8.
(b) Right, 17mm at f/2.8.​
 

Nov 16, 2004
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Figure 3. AF area is center. Focal point is the centre block of words.
17mm at f/2.8.


Figure 4. (a) Left, 17mm at f/2.8. Focal point is the tetra-pack icon. AF area is middle top.
(b) Middle, 17mm at f/2.8. Focal point is the middle block of words. AF area is center.
(c) Right, 17mm at f/2.8. Focal point is the block of Chinese characters. AF area is middle bottom.

The Verdict

  • From Figure 1, we can see that even the fine dust particles are visible and relatively sharp on Megatron. The face, neck, chest and Decepticon icon appeared very sharp. That is expected at f/11, which is thought to be the sharpess aperture for this lens and gives plenty of depth.
  • In Figure 2, the sharpness at the focal point is compared at (a) 50mm and (b) 17mm, since the aperture is fixed at f/2.8, giving a shallow depth of field. The focal point is the tetra-pack icon and in both pictures, the icon and the Chinese characters appear sharp.
  • In Figure 3, I shot a card with plenty of words at 17mm f/2.8. f2.8 was used since the card is flat and so all words should fall within a shallow depth of field. I engaged the shot at an angle, so there is some depth difference after all. However, on the whole, the focal point, which is the center block of words, appear sharp.
  • In Figure 4, I compared the sharpness at f/2.8, at three different auto-focus (AF) areas in the middle. (a) The top AF area is focused on the tetra-pack icon, (b) The middle center AF area is on the middle block of Malay and French words while (c) the middle bottom is on the lower block of Chinese characters. The sharpness is there for all the three AF areas.
The Conclusion

My copy of the Tamron 17-50mm f/2.8 is definitely sharp and accurate without any front/back-focusing issues, and there is no doubt about it. I shall heed the kind advises from nice friends and save up the money for other things.
I sincerely apologize for the members who made me excellent offers in B&S.

Is this evaluation good enough or is there other ways that I can improve?
Thanks
 

orangedial

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Feb 13, 2007
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#4
The bokeh is excellent too.
To keep this fine copy is a good decision for yourself, but bad decision for the poor potential buyers :bsmilie:
 

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