How to Keep UI elements their size?

Let me start with saying that I'm new at Unity.

I have have FPS-style scene, and I want to put a crosshair at the center of the screen. I want to use a PNG file that is 64x64 pixels in size.

I added a canvas, added an image to the canvas. The picture of the crosshair was imported and type was set to "Sprite". I set the source of the image to this sprite, and the result just looks... awful...

The image is just way to big and jagged. I can play around with the "width" and "height" to scale it down, but it never looks right to me.

What do I need to do to keep this image at 64x64 on the canvas. This shouldn't be rocket science, so what am I missing?