Today on Reel Rebel, Stephen Schweickart talks about finding the right lens with a fixed focal length and the folly of trying to use a built-in lens with a so-called 700x zoom. So if you're finally ready to get yourself a DSLR, it's time to take a look at the types of lenses that you can get, what they're used for, the advantages and disadvantages, and so on. So let's let Stephen take it away:
Overview of Fixed Focal Length Lenses
Why a Fixed Focal Length Lens?
Digital cameras that tout 700x zoom in their small built-in lenses aren't telling you that the image will go out of focus after about 10x.
Advantages of a Fixed Lens
- Closer resembles the focus of the human eye
- Less glass to worry about, more light comes through, giving you awesome shallow depth of field
- Image sharpness rules
Kinds of Fixed Lenses
You can go from single digits (fisheye) to 1000mm lenses. The human eye is close to what a 22mm lens sees, so it's best to start there. The more you go under 22mm, the more of the image you see, but the image is also more distorted.
A low focal length equals super sharp images (sweet!), but you can't really do much with the huge depth of field, so everything is in focus and you can't really change that unless you put on another lens.
A higher millimeter lens will give you more shallow focus, but it becomes harder to keep the subject in focus if there's a lot of movement. High-millimeter lenses are designed for subjects that stay put, with little or no movement. When you find a subject that works with a high-millimeter lens, though, the images can be spectacular, movie-like.