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05-06-2011, 06:42 PM   #1
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Round 1, FIGHT!

So after reading several lenses reviews from different users and websites to be used on a K-5, I still need your help to decide between the following competitors, and please, do note that I'm not taking in account any other lenses, but this ones, where the main purpouse will be IMAGE QUALITY (SHARPNESS).

So DON'T worry about their price, angle of view or utility I'm just looking for short answers from users that have already used any of this lenses:

Sigma 17-50mm F2.8 EX DC OS HSM
vs
Tamron SP AF 17-50mm F2.8 DI II XR LD ASPHERICAL [IF]


Tamron SP AF 17-50mm F2.8 DI II XR LD ASPHERICAL [IF]
vs
Tokina AT-X 28-70mm F2.6-2.8


Sigma 18-250mm F3.5-6.3 DC OS HSM
vs
Tamron AF 18-250mm F3.5-6.3 DI II LD



Thanks in advance for your time... =D

UPDATED: I got my answers, thanks everyone! =DD


Last edited by Thales454; 05-07-2011 at 08:59 PM. Reason: updated
05-06-2011, 07:02 PM   #2
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QuoteOriginally posted by Thales454 Quote

Tamron SP AF 17-50mm F2.8 DI II XR LD ASPHERICAL [IF]
vs
Tokina AT-X 28-70mm F2.6-2.8
The 17-50 is fairly wide, the 28-70 not wide at all. It's the biggest difference there.
05-06-2011, 07:18 PM   #3
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QuoteOriginally posted by SpecialK Quote
The 17-50 is fairly wide, the 28-70 not wide at all. It's the biggest difference there.
Nothing else about IQ? I've read somewhere that 28-70 may decrease contrast when the light hits the front element at oblique angle.

Can anyone confirm that?
05-06-2011, 09:11 PM   #4
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Rivals updated! =D

05-06-2011, 09:15 PM   #5
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QuoteOriginally posted by Thales454 Quote

Sigma 18-250mm F3.5-6.3 DC OS HSM
vs
Tamron AF 18-250mm F3.5-6.3 DI II LD ( I do know that it's the same build as Pentax, however, some critcs noticed a slightly better IQ with Tamron).
The Tamron 18-250mm and the Pentax DA18-250mm are basically the same lens. Manufactured by Tamron and rebadged by Pentax the DA18-250mm is basically the same product at the Tamron 18-250mm. There have been a frew thread comparing the two but the differences are really negligible.

I cannot comment on the IQ of the Sigma 18-250mm HSM lens, bit I test it (before buying a DA18-250mm). It is slightly heavier. The AF is possibly faster. But the OS (optical stabilisation) is redundant with the Pentax in-camera shake reduction (SR): you cannot use the in-camera SR and the lens OS at the same time. The Sigma is more expensive. At the end I chose the DA18-250mm.

I would tend to to recommend the Tamron18-250m/DA18-250mm over the Sigma 18-250mm although I acknowledge that you would need to buy it as an used item. (And there are excellent used copies regularly at www.keh.com, www.adorama.com (Used) and on this forum, typicaly sold between US$360 to $450.)

Overall the 18-250mm is the perfect all-around/travel lens.

Hope that the comment will help.
05-07-2011, 09:23 AM   #6
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QuoteOriginally posted by hcc Quote
Hope that the comment will help.
Thanks for the info
05-07-2011, 10:14 AM   #7
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I have Tamron 17-50 and it's an amazing lens, though there is some barrel distortion at 17mm as you can see from this picture.

05-07-2011, 11:40 AM   #8
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QuoteOriginally posted by yusuf Quote
I have Tamron 17-50 and it's an amazing lens, though there is some barrel distortion at 17mm as you can see from this picture.
Yep, it really seems to be good, one of them will be my most used lens, but I do think both 17-50s suffer from a slight barrel distortion wide open :P I haven't heard anything comparing their IQ tho.

Really nice pic btw

Thanks for the info.

05-07-2011, 02:32 PM   #9
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QuoteOriginally posted by Thales454 Quote
Nothing else about IQ? I've read somewhere that 28-70 may decrease contrast when the light hits the front element at oblique angle.

Can anyone confirm that?
No, but I have no doubt that under certain conditions, slight differences in IQ might be visible. In some of those cases, those slight differences might favor one of the two lenses; in other cases, they might favor the other.

But the difference in focal length is immediate and significant every day of week. That's the only factor that really matters here.
05-07-2011, 04:59 PM   #10
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QuoteOriginally posted by Marc Sabatella Quote
But the difference in focal length is immediate and significant every day of week. That's the only factor that really matters here.
That is true, but I think everyone would go for the one with ''less flaws'', and since this issue has also been reported by other Tokina users with different lenses I may say that I'll pick the other lens, since they do already have the same focal lenght. But as you've stated, they might be so identical that we can't name one.
05-07-2011, 08:53 PM   #11
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QuoteOriginally posted by Thales454 Quote

UPDATED: I got my answers, thanks everyone! =DD
You welcome though I think you should not remove the content from the original post, it just becomes difficult for other readers can get the context later
05-07-2011, 08:56 PM   #12
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QuoteOriginally posted by yusuf Quote
You welcome though I think you should not remove the content from the original post, it just becomes difficult for other readers can get the context later
Oh I'm sorry I thought the threads were deleted when all the issues were solved :x
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