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Old Nov 27, 2010, 3:53 PM   #1
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Default Tamron 17-50 image quality upgrade vs Canon 18-55?

Would I see a noticeable upgrade in image sharpness using a Tamron 17-50 vs my kit Canon 18-55 IS??

I see them used on ebay around $280ish, wondering if I should go for one?

Thanks
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Old Nov 27, 2010, 4:12 PM   #2
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The Tamron 17-50/2.8 is better than the Canon 18-55 IS. The biggest advantage of the Tamron is the constant f/2.8 aperture; while the biggest advantage of the Canon is the image stabilization.

The Canon 18-55 IS is better that the Tamron 17-50/2.8 VC. The Tamron VC still has the constant f/2.8 aperture, but in all other respects, it's not as good as the Canon.
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Old Nov 29, 2010, 8:17 PM   #3
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Hello
I have the same dilemma
Cant understand why its hard to produce a lens in the 17-150 range with decent image quality
the ratings for the canon 18-135 and the sigma 18-125 are not good
i have the 28-135, quite nice, but not wide enough
the 17-70 is nice not stabilised and too short for me, esp when i cant move forward to frame
the 24-105 cost is kinda high

some are not wide enough and some are not sharp st the longer end

so whats left really
frustrated
pete
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Old Dec 5, 2010, 6:46 PM   #4
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Pete,
Trying to get a rather long zoom range into a lens is an optical nightmare. I have yet to see any lens with a huge zoom range that produced good images throughout its zoom range, like the very expensive 28-300L..Long range, HUGE pricetag but in reality it sucks from one end to the other in the realms of IQ. The members of the pixel peepers club prefer all primes as they produce the best IQ. I own both and the only zoom I have that I ranks anywhere near a prime lens is the 70-200 2.8L IS II. MY 24-70L is better than the 24-105 and faster but the 35L, 50 1.4, 85L, 135L, 200 2.0L, 300 2.8L and 400 2.8L all produce stellar images. Note the only non L in my collection is the 50 1.4. I tried the 50 1.2L and found it to be marginally sharper wide open to f2 or so than the 50 1.4....past that the 50 1.4 clearly produces better images.
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Old Dec 5, 2010, 8:31 PM   #5
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Quote:
Originally Posted by deterpawson View Post
Cant understand why its hard to produce a lens in the 17-150 range with decent image quality
At wide angles, the objective lens group has to do a lot of refracting to get the light to travel down the inside of the barrel. Refracting can and often does cause different frequencies (colors) of light to bend at different rates, causing chromatic aberration. So in order to keep the chromatic aberration in check, they have to produce optical elements one way. But if that same objective lens group must also handle longer focal lengths, in order to prevent chromatic aberration in the opposite direction, ey have to produce optical elements the opposite way. And in the middle of all that, they also have to be sharp and not distort.

That's tough.
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