Interesting enough is that, both zoom lenses have IS. I found IS pretty useful when the ambient light is weak, for examples, for all indoor settings, or when the aperture is small

Read the rest here:
Oldfield's Inner/Outer World: Focusing speed

Open up the aperture of the lens to its maximum value (on prime lenses it can be as large as f/1.2, while on zoom lenses it is typically between f/3.5 and f/5.6), which will make the depth of field very shallow, shoot at an angle and …

Here is the original: 
Texture Photography