I don't like Sigma lenses anyway, but this review of the 18-50/2.8
seems fair after reading all the others. I wouldn't exactly call it
light weight though ... it weighs a pound.
http://www.topicpoint.com/sigma_18-50mm/
> Conclusion
>
> The Sigma 18-50mm F2.8 EX DC lens is a nice, light weight, bright
> lens. It serves well as a general-purpose lens, and its bright
> f/2.8 aperture is wonderful, especially given its compact size
> and light weight. The lens is sharp at f/8.0 to f/16 throughout
> its range, very good at f/5.6 and f/22, and usable at f/2.8
> though rather soft. Remember, there may be sample variance, so
> since my tests were done only on one copy of the lens, it may not
> represent the performance of another unit of the lens. It has a
> good finish, a nice feel, and its price is reasonable for its
> performance level. Its most glaring omission is the lack of a
> depth of field scale.
I'd much rather have a lens that wasn't soft wide open, and was
lighter. What good is f/2.8 if it is soft and low contrast? One stop
down from f/2.8 is not a problem, particularly if there is more
sharpness/contrast to allow for better manual focus capability. A
Pentax FA20-35/4 is a much better performer wide open and weighs half
a pound, a Pentax FA28-105 is again a better performer and weighs
half a pound. Very wide to normal, wide normal to a decent telephoto
on the DS body, which at ISO 200 minimum is just fine with f/3.2-f/
4.5 maximum aperture.
Godfrey
On Dec 23, 2005, at 7:01 AM, Jens Bladt wrote:
I'd say for all-round purposes these lenses are all too long (28mm)
and too slow (3.2 and above).
I would say a perfect all-ound lens - for me - would be a 18-50mm F.
2.8
(sigma), that is for an APS-sized senor. For full frame a 24-90mm or a
28-70mm would be great, preferably F.2.8, if possible.
For the kind of shots you show, a wide angel would give you very
fine DOF
and anything would be sharp at F.8, almost regardless of the
distance. I
have stoped buying lenses slower than F.2.8, because of the
limitations a
slow lens provides.
