Tamron has two quite successful wide angle zooms; the 17-50mm F2.8 and the 18-250/270mm designs. I'm quite surprised that Tamron after all these years hasn't come up with a competitor to the Sigma 17-70mm and an alternative to the different 24mm equivalant zooms most manufacturers now offer. They certainly have what it takes to make a good wide angle zoom, so why are they not jumping into this part of the market?
Possible designs could be (prices without VC):
Without VC, hmm, why? For Sony and Pentax this doesn't matter, but Sigma is putting more and more OS units in their lenses which would be more appealing to Canon/Nikon shooters.
16-70mm F3.5-5.6, MSRP $349
No. 1mm wider than the Sigma and 1/3rd of a stop slower, with no OS, no macro, I think this wouldn't sell well. Tokina has an option that is $50 less with more zoom.
16-70mm F3.2-4.5, MSRP $449
Sigma 17-70 F2.8-4.5 Retail Price: $470, includes OS (Stabilization), HSM (a relatively quiet and fast AF motor), and you get close to 1:2 Macro as well.
At this price point and with fewer features than the Sigma it will never sell.
Pentax also has an excellent 17-70 F4 for $480, so Tamron wont be able to sell to the Pentax crowd.
16-80mm F3.5-5.6, MSRP $399
For that range you'll never get it at that price, granted, this is the option that I would like to see Tamron make, but it'll likely never happen. It would absolutely have to have their VC unit in it and it likely would cost closer to the $550 price.
17-90mm F3.5-5.6, MSRP $349
17-90mm F3.2-4.5, MSRP $449
Again, for that range you'll never get it at that price. 90mm w/no "VC", unless they make it in only Sony or Pentax mounts, no thanks. It'll never compete against the Nikon 16-85 VR or 18-105 VR, Canon 15-85 IS or 18-135 IS and possibly have trouble even competing against the Sony 16-105 or Pentax 18-135.
17-105mm F3.5-5.6, MSRP $399
Sigma 18-125 F3.8-5.6 OS HSM...$339 @ bh. $60 less, more range overall, and "OS".
Nikon has an 18-105
VR for $400, and Canon has an 18-135 for $450. You'd never be able to sell this lens to two of the biggest markets - especially considering that these lenses are also sold a 'kit lenses' on some of the cameras.
Oh and Tokina makes this already: 16.5-135mm f/3.5-5.6 AT-X DX AF. It sells for $299, no "VC" but more range than anything you listed, also it's priced lower than anything you listed too.
Some times it's not all about being a competitor, sometimes it's about being different. (e.g. 18-270 PZD.) Yes, Tamron doesn't make a competitor to the Sigma 17-70, but what's wrong with the Sigma, every copy I've ever used/tested has been flawless, and on more than one occasion made me rethink my decision to spend an extra $350 more for my Canon 15-85. Personally, as long as
someone makes a lens close to what I need, I don't care who makes it (Tamron, Sigma, or Tokina - or one of the major manufactures). Lens Manufactures, I'm sure have done more market research than every person on every camera forum combined in figuring out what will sell. Now sometimes that research takes time to bring a lens out to market. Sorry, I don't mean to be a downer, but much of what you listed is either impractical, already been done, or in a couple of cases more money than a competing product.
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I'm critical because I care. I don't criticise things with no potential, so take it as a good sign.
http://flickr.com/photos/56983515@N00/
http://pentaxlensrange.blogspot.com/2010/04/pentax-is-still-missing-few-lenses-to.html
Current cam: K10D, TZ1
Wish cams: LX5, XZ-1 or 4/3 pocket cam with fixed stabilized zoom lens.
Current lens: 18-55mm F3.5-5.6, 50mm F1.4, Sigma 105mm F2.8 macro
Wish lens: 16-90mm F3.5-5.6 or 17-90mm F3.2-4.5, a 70-300mm F3.2-4.5, usable quality with 1.4TC, 60mm F2 macro, 135mm F2.8 macro.
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NHT
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