(I haven't checked whether they all can be used with Canon systems, just to give your 'addiction' to bokeh and background blur something to chew on.)
An entire thread about lens bokeh: http://www.clubsnap.com/forums/showthread.php?t=479460
Not the best photos I've ever taken but here is one. Here's another one. Both taken with my Olympus kit lenses.
You can see that there are parts of the photo in the background that are out of focus.
What's more, Olympus is reknown for having greater depth of field than brands with bigger sensors at the same f number. What more for Canon and Canon kit lenses?
Olympus ZD 40-150 f4-5.6
The last 2 pieces of info are not too important here. Note that:
1. f5.3 is the smallest f number avaliable at my focal length
2. 119mm is quite a large focal length- it is equivalent to about 149mm on your Canon crop frame lens (ie. zoomed in quite a bit)
3. The background is quite a distance away.
This contributes to the bokeh you see. You do not need a fancy lens. Neither must you buy Olympus lenses to acheive shallow depth of field.
Stop talking on paper and just go out and shoot. You already known enough to start. You need to see the effects with your own eyes. Try with your kit lens first. Do it right and you can get nice OOF blur as well.
Very, very much agreed. It has been said many, many times. If I'm not wrong, links to Sulhan's notes have been given twice. I've already given you proof that it can be done with a kit lens, so yes. Go out there and shoot.
Unless you need a physics explanation too...
Depth of Field: http://toothwalker.org/optics/dof.html and http://toothwalker.org/optics/dofderivation.html
But that's rather something for a rainy Sunday and requires some decent knowledge about Physics. Not the level of some Wannabe Education Channels ..
finally understand what senifer meant by.. You can understand it in 1 shot, SNAP! and you understand.
and it also could be after 60shots and you still don't understand why.
That's because the kit lens has variable aperture.
f3.5 is the smallest f number you can use at 18mm, f5.6 is the smallest you can use at 55mm.
Just another thing to note, please get your terms in order: aperture cannot be higher or lower. Aperture is not the same as f number either. That is, f 5.6 does not mean the aperture is 5.6.
Aperture refers to the opening that allows light to pass through in your lens. Since it is an opening, it can either be bigger or smaller but not higher or lower
F number is inversely related to aperture. If you have a small f number, your aperture is bigger. By the laws of physics, this translates to a shallower depth of field, and not "bokeh effect".
Please stop using the wrong terms. Not only is it factually inaccurate, it confuses people who are trying to understand what you're trying to say.