The EF 50mm f/1.4 is a fixed length lens, and the 18-55 is a zoom lens that can shoot at any of the lengths between 18 and 55.
The reason someone would want to get a fixed 50 when they already have 50 covered in an 18-55 lens?
Much brighter lens. The f/1.4 lens is 3 stops faster than the zoom lens. That means it lets 8 TIMES MORE LIGHT into the camera in the same amount of time. That means when you are shooting indoors and lighting is not bright like outdoor sunlight, you can use a shutter speed that is 8 times faster than what you could get using the kit zoom lens. That is hugely important. If you had the zoom lens you might have so slow a shutter that your subjects are blurred from motion, or you might have to raise the ISO setting higher to compensate, and that gives ugly grainy images.
Shallower depth of field. With a wide aperture lens like the f/1.4 lens, you can isolate your subject from the foreground and background. This is one big difference between an ordinary snapshot and a nice photo. You can get rid of distracting things in the shot by making them out of focus.
Sharper and lighter. In trying to make a zoom lens take acceptable images at every length between 18 and 55 the designers have to make compromises. It is not going to be a stellar sharp image quality at any length because it has to be decent at all lengths. The fixed length lens, however, can be designed to be sharp at that one length. It is also usually a lighter lens, though those kit zooms are pretty light too, really.
You may also consider getting the new 50mm f/1.8 STM lens. It is a great upgrade to the previous "nifty fifty" "plastic fantastic" 50mm f/1.8. The old version was slow and noisy to focus. It had just 5 aperture blades and they were straight so the out of focus highlights would appear like little pentagons. The new STM is fast and quiet at focusing, has more aperture blades and they are curved so the highlights are nice and round. It also has some lens coatings that cut down on flare and give a more saturated image. The price is just $125.00.
I love fixed length "prime" lenses. My everyday walk around lens for 2 years has been a 35mm fixed prime and it makes my photography look and work better.
Scott
Canon 5d mk 4, Canon 6D, EF 70-200mm L f/2.8 IS mk2; EF 16-35 f/2.8 L mk. III; Sigma 35mm f/1.4 "Art" EF 100mm f/2.8L Macro; EF 85mm f/1.8; EF 1.4x extender mk. 3; EF 24-105 f/4 L; EF-S 17-55mm f/2.8 IS; 3x Phottix Mitros+ speedlites
Why do so many people say "FER-tographer"? Do they take "fertographs"?
One or the other.
