I like to shoot in Aperture Priority Mode a lot. That said, it is important to know what to expect at different apertures so that you can choose the one that will be the best for what you are trying to accomplish in a given scenario. So, I thought that I would put together a little example of what all of the "true apertures" look like on my camera (Canon EOS 5D Mark II) with the EF50mm f/1.8 lens. All of the photos were taken at ISO 1600 with no flash or exposure compensation and focused manually on the small statue in the foreground. I will note the aperture and accompanying shutter speed for each image so that you can take note of the relationship. Once you know the true apertures on your camera you can figure the shutter speed at one aperture and know what it will be at all of the others which can be helpful when shooting in full Manual mode. Here we go!
F2.0 1/60 second