03-14-2011, 10:40 PM
[quote name='thxbb12' timestamp='1300141374' post='6775']
Well, I've never tried the Sigma 18-50, but from this very website the IQ is not as good as the Tamron.
Also, the thread you point out on pentaxforums seems to be a case of FF issue.
The Tamron is generally considered to be one of the best f/2.8 standard zooms for sharpness. However it seems to be more prone to focus issues than the Sigma.
This being said, I know nothing of the new Sigma 18-50 with HSM. Perhaps they improved the IQ?
[/quote]
Not even this verey website has showed that the Tamron is "better". The lenses have been tested with a lot of time between them.
It is just that just about everyone who has tried them side by side perfers, on the whole, the Sigma.
The HSM version is Nikon only, and has not changed optically. The Nikon version relied on the Nikon internal motor, hence the update for the Nikon mount version later, with HSM (D40/40x/60/3000/3100/5000 all lost the Nikon internal motor).
The Canon version kept its old motor, and the Pentax version remained motorless.
To recap:
People who have used both comment on the better, more silent and more accurate AF from the Sigma. They comment on a better IQ on the whole, specifically at wide angle (less CA problems and more contrasty). Also the better build and closer focus are seen as plusses.
The side by side samples to be found never show the Sigma to be inferior.
The Tamron is a lens which is good, but has a reputation it not really deserves.
Well, I've never tried the Sigma 18-50, but from this very website the IQ is not as good as the Tamron.
Also, the thread you point out on pentaxforums seems to be a case of FF issue.
The Tamron is generally considered to be one of the best f/2.8 standard zooms for sharpness. However it seems to be more prone to focus issues than the Sigma.
This being said, I know nothing of the new Sigma 18-50 with HSM. Perhaps they improved the IQ?
[/quote]
Not even this verey website has showed that the Tamron is "better". The lenses have been tested with a lot of time between them.
It is just that just about everyone who has tried them side by side perfers, on the whole, the Sigma.
The HSM version is Nikon only, and has not changed optically. The Nikon version relied on the Nikon internal motor, hence the update for the Nikon mount version later, with HSM (D40/40x/60/3000/3100/5000 all lost the Nikon internal motor).
The Canon version kept its old motor, and the Pentax version remained motorless.
To recap:
People who have used both comment on the better, more silent and more accurate AF from the Sigma. They comment on a better IQ on the whole, specifically at wide angle (less CA problems and more contrasty). Also the better build and closer focus are seen as plusses.
The side by side samples to be found never show the Sigma to be inferior.
The Tamron is a lens which is good, but has a reputation it not really deserves.