Prime Vs Zoom
A prime or fixed focal length lens is one where you need to get closer or farther away from a subject to frame correctly. These lenses are typically lighter, faster and cheaper as they do not require motors or devices inside the lens.
Their quality is unsurpassed, yet they make that a trade-off for versatility.
There will be situations where you can’t move physically, yet still, need to get a tighter frame on a subject. The Canon EF 50mm f/1.8 II or Nikon AF Nikkor 50mm f/1.8D are the perfect examples.
A zoom or variable focal length lens is one where you can ‘zoom’ in and out of a scene.
This means that by standing in the same place, you can tighten or loosen the frame around the subject. Typically, they are more expensive and heavier due to the amount of machinery needed inside.
Remember, they need to move and focus at a whole range of focal lengths.
They also have a lower quality overall than prime lenses, and they don’t allow you to open your aperture as wide as a prime lens. The Canon EF 24-70mm f/2.8L II is a perfect example.
Different Types of Lenses
Fisheye/Ultra Wide Angle
A fisheye or ultra wide angle lens is a lens that achieves extremely wide angles of view. The focal length of a fisheye lens is the smallest focal length you can find in photographic lenses.
These lengths can be anywhere between 4.5mm and 24mm, where the angle of view is anywhere between 100° and 180°.
When it comes to using these lenses, you will find that there are the different types; circular cropped circle and full-frame.
A circular lens will give you a circle image, a cropped circle will give you images with curved sides, and the full-frame will give you a rectangular image, cropped from the captured circular image.
In terms of positive uses, they will capture very wide panoramas and skyscapes very well. They have been used for cityscapes, as they give you an ultra-wide view.