Romax12 wrote in post #15947090
I keep hearing people saying:"it's a kit vs pro-level" - but I don't understand in which ways?
build quality? nahh.. i guess its not really a factor in the decision.
sharpness?contrast?saturation? probably, but I don't have any other lens to compare though.
af speed? yes. I would like to get the fastest auto-focusing available today.
aperture? hell yeah. I want the background to melt away. i keep looking at the samples thread and being amazed at the bokeh quality this lens can produce.
if there are other factors I forgot please help me!
The 18-135 is not built to near the standards of any L-lens. If you baby your equipment this won't make much difference. I use my stuff; as such it gets bumped around a bit.
Sharpness is a factor. Saturation and contrast are easy to adjust in post. I don't worry about them, too much. You can't add sharpness the lens did not capture. In my experience the 135L is better, in all 3 categories, at f/2 than the 18-135 is at any aperture.
Aperture can affect background blur. So does distance. You could shoot the 18-135 at f/8 and get similar amounts of background blur compared to the 135L at f/2, but the background would need to be MUCH further away. Yes, f/2 is better for that. The f/2 aperture really shines when it comes to shutter speed, or ISO, when you need them. This is the difference between ISO 200 and ISO 1600, or 1/125 and 1/1000. This is HUGE in shooting action. I bought my 135L specifically to shoot indoor basketball. You will never do that with an 18-135, if you care much about the results.
In conjunction with the fast action-stopping aperture, you will need fast accurate focusing. Most, if not all, Canon bodies made in the last 10 years or so focus faster, and more accurately with an f/2.8 or faster lens than with an f/5.6 lens.
If you are shooting things that move, the 135L is vastly superior to the 18-135 in almost every way. The 18-135 does have IS. How much it helps when the shutter speed is above 1/500 is questionable. If you shoot static objects at f/8, you probably won't ever see the difference.
Allow me to repeat, IMHO, the 135L is too long to be practical on a crop-sensor camera. That is why I went to a 70-200 2.8. The zoom is just more versatile. I lose 1 stop of light, yet retain the quick, accurate AF. And again, now that I have 5D, I'd love to give the 135L a second chance.
The 18-135 is a good, all-around general purpose lens. I used mine for years before upgrading to the 15-85. What it is NOT is a low-light and/or action lens. That is where the 135L shines. Lots of users tout it as THE portrait lens. I don't think I ever used it in that manner. I hope some of this helps.