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05-21-2008, 07:59 AM   #1
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how much better Sigma 17-70 than Tamron 18-200?

In the common range, how much improvement is the Sigma 17-70 over the tamron 18-200?
Contrast, distortion, color rendition, vignetting?

And is it really wider?

thank you for any answwer,


05-21-2008, 08:23 AM   #2
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I havent checked the 18-200 but I can tell you I highly doubt a telephoto zoom covering that much of a range (18-200) could be as good as a shorter coverage.

Coming back to the 17-70, it seems like a very decent lens with a nice coverage. It is one of my possible kit lens replacement.
05-21-2008, 11:01 AM   #3
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It's also significantly faster than the ultrazoom.

Usually ultrazooms are bad, there are occasional exceptions. I believe most people prefer the 18-250 over the 18-200.

I use a combination of a Sigma 17-70 and Tamron 70-300 myself. This gets me much more speed at the wide end.
05-21-2008, 01:59 PM   #4
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I am not familiar with the telezoom but I have the 17-70 and to be sure it is a great lens. Leave it on the camera as a walkabout everyday lens and you will be more than pleased with the results.

05-22-2008, 07:24 AM   #5
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Original Poster
thank you very much everybody for your answers.

yes, the Sigm,a should be better, but the thing is:

I already have the Tamron 18-200, had bought it used together with my Pentax *istDs, both in like new condition, the set for a very good price.

I also have a small range of old manual lenses, mostly M42 Takumars and the IQ I get from those is SO much better than what I get from the Tamron which I therefore soon stopped using.

The reason I asked how it compares to the Sigma: the store where I bought my camera + the Tamron also has a used Sigma 17-70 for almost the same price they sold the Tamron for and I still could try to exchange it. However they might not want to and I am not sure if I should try to, because: is the Sigma 17-70 really a step up big enough to satisfy me?

Not wanting to spend the big bucks but aiming for better IQ I am more drawn towards the Tamron 17-50 than to the Sigma, also for being faster. ( I am more of a wide shooter anyway, could get some tele range zoom later, and I am sure I could sell the Tamron for the price I bought it for, so no need to beg for an exchange )
I should refrace my question:

Tamron 17-50 Vs Sigma 17-70 ?

besides the missing range, is the Tamron a clear winner?

or is there any other budget contestant that offers good IQ in the range from min 17mm to min 50mm or more?
thank you so much for your insight,
05-23-2008, 07:27 PM   #6
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Don't know how it compares to the Tamron but what about the Sigma 18-200mm?
Check this out.

Found on

05-23-2008, 08:21 PM   #7
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Folks say the Tamron is not as good in contrasts, sharpness and colors. I don't know, all I can say is the 17-70mm is like the DA18-55 on steroids, with all it's goodness and much more.
05-23-2008, 09:16 PM   #8
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i dont think its not fair comparison between two of them.. one is covering short to medium and the other is a 'clean sweep' all focal lens..

the last one i think must be have something to sacrifice in picture quality..

05-26-2008, 06:42 AM   #9
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Original Poster
thank you everybody very much for your input, you are all very kind and helpful.

I went back to the shop today. They had a used Sigma 17-70 and a used Pentax 16-45 f4. Tammy 18-250 and Tammy 17-50 they only had new which would have meant adding another 300 + USD in exchange for the Tammy 18-200 which I had bought used from them and I did not want to spend that much.

I did fast and dirty comparison shots of the three, that is tammy 18-200, Pentax 16-45 and Sigma 17-70 wide open and at f8 at their widest focal lenght and at about 70mm ( 45 mm on the Pentax )

From what I could tell reviewing the photos, above all corner performance, on the camera's LCD my conclusion was:

At their resp. widest focal point the the Sigma is the sharpest, specially at the corners. The biggest difference was to be seen at the widest end and wide open where the Tamron 18-200 really looked quite bad and the Sigma at f2.8 still won over the Pentax at f4.

I got the Sigma 17-70, it won over the Pentax 16-45 for being faster and longer with at least comparable IQ. I did have to pay about 50USD for the exchange but I am very happy because the improvement in IQ is obvious.

Would there also have been a used Tamron 18-250 I could have taken instead the decision indeed would have been very difficult. I had checked sample images on the net and amazingly but truly the Tammy 18-250 does compete with the Sigma 17-70 in IQ. But as I like shooting street = wide angle and at low light the Sigma may well be the better choice for me anyway, I am very happy with the lens!

Also to mention that the auto focus of the Sigma is much smoother, faster and less noisy that that of the Tamron 18-200 ( no idea how these compare to those of the 18-250 )
thank you,

Last edited by kuuan; 05-27-2008 at 03:33 AM.

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