Tamron "Duff lens/lens"

[mrvista]

Hi all, just after some advice.. I am looking to buy either a Tamron 28-75mm f/2.8 XR Di LD or a Tamron 17-50mm f/2.8 XR Di-II LD for my Nikon D90.
After looking at various reviews I see a familiar theme pop up..." I bought a bad one, it has very soft edges at low aperture".
The end result seams to be that the lens is exchanged.
After some more research I also find that a lens has a "sweet spot" around F8/F11, would this not mean then that soft edges at low aperture are normal?
Tamron also do a VC version of the 17-50, is there a big difference?
Cheers

[arthurking83]

Both good to great lenses.

The 28-75 takes off at f/4 and can be a little soft(but acceptable!!) at f/2.8(depending on your requirements. It has the better bokeh of the two lenses, and will cover the full frame of an Fx camera if you ever require that in the future.
The 17-50 is definitely sharper at f/2.8 across it's equivalent focal lengths and then any difference from f/4 and onwards is academic, and only noticeable at pixel peeping magnifications looking directly at sequential images.

28-75 is a nicer portrait lens, whereas 17-50 is more of a general all pupose kind of lens better at landscapes due to slightly better sharpness and wider FOV, and can do portraits well as 50mm is good for that.
You'll find that the 11mm difference at the wide end is more significant than the 25mm at the long end is going to be. How you prioritise that significant difference at the wide end vs the log end is only ever going to be best judged by yourself(sorry for the copout ) but I have 'em both(non VC version of the 17-50) and they both serve a purpose.
If I ever go Fx, then the 17-50 becomes redundant and will go, as the 28-75 becomes the 17-50 equivalent anyhow.. just on a wider format. 17-50 therefore becomes more dispensable to me.. even though the images are slightly nicer in some respects.

if you could spring for both, then do so.
If it were a choice of one or the other only, then the 17-50 with VC makes the most sense for a greater majority photography useage.

[kwokask]

No comment re soft edges.
Re the VC version of the 17-50, apparently marginally not as sharp as the original (I think that was the conclusion of Photozone).

[mrvista]

Cheers for the info, I think I am steering towards the 17-50 vc.

[MarkChap]

I have the 17-50, non VC, man it is sharp.

Haven't particularly noticed any edge softness, but then I don't pixel peep too much either.

[bigdazzler]

I agree with pretty much everything AK said.
Ive had both and they are both very good bang for your buck. I got rid of the 17-50 when I went up to FF, and i now use the 28-75 as my general walkabout lens. The 28-75 is a really nice lens. Super sharp from f4 (my copy is pretty damn good wide open as well), nice colours, contrast, and bokeh for portraits. You wont regret either, but the 28-75 has a slight edge IMO.