18-135 canon vs sigma 24-70 vs canon 17-55

Ok guys

I've got a 18-135 at the moment and was wondering how much an improvement would my pics be with the other two lenses?

Most of my photography is portrait studio based.

I was wondering if anyone would kindly take pics of the same scene with the different lenses?

Many thanks

The EF-S 18-135 is an outstanding lens IQ wise. It has a round aperture hole for good blur and reasonably fast focus. And a good IS system. So what kind if improvement are you looking for? The F2.8 EF-S 17-55 is a little faster than the F3.5 18-135. So if you have need for additional speed. Some lenses may have a better build quality than the 18-135 so it that is an issue.

Mike

No i fully agree in the sense that the pics i've taken with the 18-135 are really really good.

speed isnt an issue as the shots are posed and time is taken to ensure the model is right before an image is taken

the quality of the image is more my aim to improve - as they say better glass better results - i wanted to know if the result upwards would be worth the extra investment (but would also mean me having to sell my 18-135)