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06-11-2011, 07:19 PM   #1
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Tamron AF 18-200mm vs Sigma 18-250mm

I need a general walkabout lens with macro features.

I am looking at the Tamron AF 18-200mm & Sigma 18-250mm. I know that the Sigma 18-250mm is a newer and better than the Tamron AF 18-200mm, but the the Sigma costs $230 more. Is the Sigma worth that extra $230?

A side issue, the Sigma 18-250mm costs the same for the Pentax and Canon mount. If this is the trend for new Sigma lenses, I wonder if will effect the market for the Pentax. One of the advantages of the pentax is the lower cost of non_VR lenses. However, if this disppears, then why even consider Pentax.

This is a personal issue for me as I plan to upgrade from my KX. If I have to spend the same $$ on glass for the Pentax or Canon/Nikon, then I am tempted to go with the more adopted brand.

06-11-2011, 07:59 PM   #2
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There are several relevant threads in PF on this topic. You should read these.

There are basically 3 generations of 18-250m walk-around lenses plus a new entry (18-135mm).

The Sigma 18-200mm and Tamron 18-200mm are the first generation.Older lenses with average IQ.

The Tamron 18-250m/Pentax DA18-250mm may be regarded as the next generation. The DA18-250m was manufactured by Tamron and rebadged. The Tamron/Da18-250mm can be found 2nd hand/used for about $350-$450. It has an excellent track record. The lens is very sturdy and the IQ is excellent in its category. A marked improvement from the older 18-200mm Sigman & Tamron lenses. See for examples the independent reviews at and

The newer Sigma 180-250mm OS HSM is less tested. It is regarded by its users as close to the DA18-250mm in terms of IQ. OS is regarded as an advantage but it is also redundant with the in-camera SR. Its drawback is the larger price.

A new walk-around lens is the Pentax 18-135mm WR. While its range is narrower, the lens is weather resistant.

Both the Tammy/DA18-250mm have an excellent record among Pentaxians and van be highly recommend. In value for money, an used Tamron 18-250m is possibly the best solution IMO although the DA18-250mm is also a good solution.

You also wonder about Pentax versus Canon/Nikon. Let me share my experience. I was in a 'similar boat' two years ago. At the time I chose Pentax because I wanted WR. Pentax is the only brand which offers reasonably-priced weather resistant (WR) bodies and lenses. I learned quickly another major advantage of Pentax: the backwards lens compatibility. There is a broad market of excellent/outstanding older lenses that are compatible with your camera and in particular some truly outstanding prime lenses. Visit the lens database at PF for example.

Hope that the comment will help.

Last edited by hcc; 06-11-2011 at 08:36 PM.
06-13-2011, 01:04 AM   #3
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I had the Tamron 18-200 a little while ago and was pretty happy with the results. As long as you understand that you are paying for the convenience of being able to use 18mm to 200mm without having to change lenses because the IQ is decent but not great. I used it primarily when changing lenses multiple times was not viable.

But to answer your exact question, no I do not think the 18-250 models are worth the extra $$. With any superzoom you are not going to get superb IQ, the difference between the 200 and 250 is noticeable but you'd be better off saving the $$ and putting that towards another lens or in your pocket for something else you need.
06-13-2011, 09:48 AM   #4
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the sigma 18-250 has HSM right? so it would be near silent and fast auto-focus. at least this is good....

06-13-2011, 09:28 PM   #5
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I searched the net for used Tamron 18-250m or DA18-250mm. I can not find one with the Pentax mount. But many for Nikon and Canon.

Also, the only DA18-250mm I found costs more than a new Sigma 18-250mm!

Also, at around $400 for the Tamron 18-250, would it be better to get the newer Sigma with HSM for and extra $50?
06-15-2011, 09:31 PM   #6
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The Sigma 18-250 is also a *lot* bigger and heavier.

The Tamron/Pentax 18-250 was discontinued, but not hard to find used. It's considered the best of the bunch, and isn't much bigger/heavier than the 18-200, but still twice the price.

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