maybe it wouldn't be as apparent on your camera, but I don't know what those photos were shot on to begin with.
But here's the deal - don't get the lensbaby, it's a bad idea.
For the sake of you understanding, read all this -
SLR means single lens reflex, meaning there's a mirror/prism that allows you to look directly through the lens that's on the front of your camera.
When companies started making Digital SLR cameras, they modeled them after 35mm film cameras. However, they made the digital sensors smaller than a piece of 35mm film. This changed the perspective of the image recorded, as it was effectively cropping the field of view of the lens. Eventually, they started making sensors for the professional level DSLRs that were the size of a piece of film, which they call "Full Frame", and the cameras that had the smaller sized sensors started to be called "Crop Sensor".
Companies make lenses specifically for crop sensor cameras that won't project an image on the entirety of a full frame sensor (it would produce crazy vignette), because they are lighter and cheaper. Also, because an 11mm lens would be stupid wide on a full frame body, but because of the crop factor of smaller sensors, it will appear to be the equivalent of about a 16mm lens (depending on the size of your sensor, there are a couple different sizes).
The Rokinon/Bower/ProOptic etc would be your best bet for a fisheye. They don't make the only true fisheye for Canon, as Canon themselves and a couple other companies make them too. But, it's the cheapest and best image for the money.
here's the difference between fisheye and ultra wide angle:
with a wide-angle, it's super wide, but all the lines remain straight. It looks obviously wide, but not linearly distorted
with a fisheye, lines that should be straight are distorted. Can look cool for action, not so much for architecture (In most people's opinion anyways)