KM vs Tamron vs Sigma

[satay16]

Which is better?:
KM 18-200 F3.5-6.3 DT
Tamron 18-200 F3.5-6.3 Di II
Sigma 18-200 F3.5-6.3 DC

From given specs, i gave up trying to compare them. all are too alike.

[dr34mc4st3r]

did u try a search at dpreview.com KM DSLR forum? tons of info and opinions there. but i think i will go with KM's own 18-200

[satay16]

large range zoom lenses has always been regarded as poor performers. is the poor performance really really poor as compared to small range zooms?

[GENO]

Originally Posted by satay16 large range zoom lenses has always been regarded as poor performers. is the poor performance really really poor as compared to small range zooms?

more zoom means more glass and movement in the lens, so which means its not only slower, less bright ( smaller aperture) .

[TME]

Originally Posted by satay16 large range zoom lenses has always been regarded as poor performers. is the poor performance really really poor as compared to small range zooms?

How big do u want to print? How particular are u?

[satay16]

not so sure actually. i print from 3R to S8R at random. but are this large-zoom range lenses really very slow to focus? like 2 secs or longer?

[tankm]

Originally Posted by satay16 not so sure actually. i print from 3R to S8R at random. but are this large-zoom range lenses really very slow to focus? like 2 secs or longer?

Focusing depends on the light condition you are in, and where you aim. I have the SIGMA 18-125, and the focusing is not bad and doesn't take 2 secs. in normal lighted room.

[jsbn]

Originally Posted by satay16 not so sure actually. i print from 3R to S8R at random. but are this large-zoom range lenses really very slow to focus? like 2 secs or longer?

focusing depends on where u aim and the ambient light condition.

[TME]

Also depends on which focus sensor u use...

[muko]

Originally Posted by TME Also depends on which focus sensor u use...

TME...

is what you mean the center one is more faster and accurate han the others on the edges?

i have this kinda feeling...

[TME]

Originally Posted by muko TME... is what you mean the center one is more faster and accurate han the others on the edges? i have this kinda feeling...

Yes definitely... the centre focus is a crosshair focus sensor... so it will focus as long as there is an edge vertical or horizontal... whereas the other sensors are only single direction sensors... if the sensor is horizontal and your picture has lots of horizontal motifs, the AF suffers.