First shots using D50 + Tamron 17-50 f2.8. C&C welcome.

cutsman

macrumors regular
Original poster
Jun 1, 2006
202
0
Purchased a Tamron 17-50 f2.8 to replace my kit lens about 2 weeks ago. Finally got the chance to try it out this weekend. These were taken Sunday afternoon. I'm really liking this lens so far. Let me know what you guys think. As always, C&C is always appreciated! Thanks!









 

irontony

macrumors member
Dec 10, 2005
82
0
New Zealand
Wonderful. Appreciate the post, I too am seriously going to swap out my kit lens for this very same Tamron - so thanks again for posting - great pic's
 
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walangij

macrumors 6502
Mar 10, 2007
396
0
MI
Love the last two, the first is interesting in that the leaf in the foreground is mirrored in the back, don't know what term that is. But that tamron is a great lens, sure do miss it.
 
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Padaung

macrumors 6502
Jan 22, 2007
462
78
UK
Photos looking good. Liking the first one a lot.
Were any of the photos shot at 2.8?

I've had 2 copies of this lens - the first was sharp as anything at 2.8, but it got smashed when I knocked my tripod over and the lens took the force of the fall!

My current copy of the same lens I need to stop down to around 4.5 before the shots are sharp - I didn't test the lens out when I first got the replacement either, as the first one I had was so good. It was only when I needed all the way to 2.8 a while later that I found this out.

I've got a dud - grrrr.

Had it too long to take back now, too. Kicking myself for not testing it, as should have known better.
 
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cutsman

macrumors regular
Original poster
Jun 1, 2006
202
0
These were the aperture settings for the photos:
1. f4
2. f2.8
3. f4
4. f8
5. f2.8

My informal testing has shown that f2.8 on my copy definitely does not seem as sharp as f4 and onwards. However, I'm not sure how much of this is actually attributed to the shallow DOF as opposed the lens actually not being sharp.
Should I even expect f2.8 to be as sharp as the smaller apertures or is this unrealistic?
 
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ChrisA

macrumors G4
Jan 5, 2006
11,617
438
Redondo Beach, California
My informal testing has shown that f2.8 on my copy definitely does not seem as sharp as f4 and onwards. However, I'm not sure how much of this is actually attributed to the shallow DOF as opposed the lens actually not being sharp.
Should I even expect f2.8 to be as sharp as the smaller apertures or is this unrealistic?
The best way to test is to shoot something flat, like
a sheet of newspaper taped to a wall. The do 4X
blowups of parts in the center and the edges. With my D50 I've found that the weak link as far as sharpness goes is the sensor. There is a low pass filter that blurs the image bonded to the CCD. I think this is why my lenses
appear to have exactly equal sharpness. All of mine of Nikors

Lenses are never perfect even if built exactly
as designed. They will have some un-corrected optical
aberrations. These will always be worse with wider
apertures.

On the other hand there is another law of optics that says a perfect lens will have resolving power proportional to the physical diameter (physical diameter, or focal length over f-stop) This is cause by the wave-like nature of light.

The two rules balance together and the result is a curve. Typically it peaks at about one or two f-stops from wide open. But some very good lenses peak at maximum aperture. Canon publishes MTF curves for their lenses. I wish Nikon did
 
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Padaung

macrumors 6502
Jan 22, 2007
462
78
UK
This is the main difference between Nikon and third party lenses. Setting up a factory to do exact reproducible work is not cheap and easy. Quality control and testing is expensive.
Too true. The Nikon equivalent is 3x the price though, and I don't go to 2.8 that often. Get what you pay for...


My informal testing has shown that f2.8 on my copy definitely does not seem as sharp as f4 and onwards ...
Should I even expect f2.8 to be as sharp as the smaller apertures or is this unrealistic?
It is normal for the extreme aperture results to be not quite as sharp as the mid range settings ie f5.6-f16 are normally the sharpest settings in all lenses. Again, there is sometimes a slight drop in sharpness as you get to the other extreme end of the lens' aperture range too (eg f22 with this Tamron lens). This is usually much less, if ever, an issue as it is so neglible.

Third party lenses, as ChrisA so rightly said, have a reputation for more variance in the quality control of their lenses. Buy a pro Nikon/Canon lens and you know the chances are it will be top notch, even wide open. This Tamron lens is marketed as a pro lens, but as my example shows you can sometimes get a lens where the extreme wide aperture is unacceptable. It is unfortunately the same problem with Sigma and Tokina. This is the main benefit of buying such a lens from a store and not on-line - you can take it back and swap it easily.

Your two shots at 2.8 are looking pretty good to me.
 
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milozauckerman

macrumors 6502
Jun 25, 2005
477
0
There are very few, if any, lenses in the world that are as sharp wide open as they are at smaller aperture. Even $3500 Leica lenses improve as you stop down (though a wide-open Summilux will put many a lens to shame).

At f/2.8 you're aiming for acceptable sharpness and from what I can tell here, these are definitely acceptable.
 
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