I have talked some about why focus matters, but wanted to spend some time on the absolute magic of a fixed focus lens.
There are two types of lens out there, or at least two that I know of. Ones that zoom in and out — allowing you to manipulate their depth of focus, and single or fixed focus lenses.
A fixed focus lens will put into focus whatever is at its focus length. So a 105mm lens, for example, will only focus on things at that distance. The result is that anything at 0-104mm will show up at varying degrees of blurry, as will anything at 106mm on.
What makes this lens so wonderful is that it can make the same scene look different depending on how far away you are from your subject. It creates super creamy backgrounds for anything out of its range, and it even has the ability to capture the shape of light in its focus pass. In short - I love.
So this is the grass my front yard transformed into a beautiful blur of color and movement because of this lens (105mm). The circles highlight the same drop of water in each image.
Side note: Paradoxically this lens is also used to create super detailed images. Photographers take shots using this lens millimeter by millimeter then stack them all for a hyper-detailed images like these.
Look at how beautiful the lens shapes the light at the front of the image.
