what are you photographing?
IS can help stabilise the image, but it won't stop motion...
I find the lowest shutter speed I can get down to without handshake blur is about 1/30 but that all depends on how "stabilised" you are too...
to check though, i duno about other lenses but my 70-200 2.8 makes a sort of vibrating noise whenever the IS is on, and when you look through the viewfinder and shake the camera round a bit you can usually see the viewfinder screen is "stabilised" in a sense...
Image Stabilizer / Vibration Reduction etc only help up to a certain number of f/stops. So usually you'll see improvements like on a kit Canon 18-55mm IS lens, maybe 1/100 you see some blur, IS can help perhaps up to 1/50.
It's an aid tool, not a miracle worker... some things like trembling hands, shooting from a moving vehicle as well as fast-moving targets all contribute to "blur".
well...since u selected aperture priority, the camera selects the shutter speed for u. the only way is to up the ISO. of course u can by pass this by using programmable mode and decrease the shutter speed urself. but that might result in blur
wha lan eh 1hz to 7hz???? hahahha not all of us are mathematicians la. (i understand though)
anyway, different lenses claims different IS efficiency. like yours maybe its a 1stop IS. means lets say the longest shutterspeed you can hold w/o handshake is 1/60 (at a certain focal length). with this IS, you can theoratically hand hold 1/30 w/o hand shake (at the same focal length). some better IS claims 3stop IS.
and as they say, dont be reliant on IS. its not a miracle worker. working your holding position. hold it like you holding rifle in army. chicken wing closed. control your breathing. and lean against something if possible. the best is PRONE la HAHHAHA.
Well... the easiest rule of thumb I've come across to remove hand-shakes is the following:
Shutter speed = 1/(focal length * F) where F = factor of 1.5 to 2
Most places say 1.5 is enough, but to be paranoid you can use 2.
IE shooting with an 18-55mm, 1/100 should be safe for normal handshakes. a 75-300, use 1/600 if you're zooming all the way. Don't forget that EF-S has a *1.6 factor, so if you really really want to be picky, use 1/150 for 55mm shooting.
I personally usually shoot with Shutter priority and toggle 1/200 as my walkaround outdoors. I bump my ISO up to max 400 if needed and let the camera determine aperture. For beginners, just use this method, slowly experiment with the other settings at your leisure.