Photography help and tips on lens?

Question

i want to get a lens that will let me blur background really good. how do i go about choosing this?

i'm new to LENS, but i've been taking pictures on DLSR for about a year now.

will i need to look a the F stops and what do they mean?

say compare these two f stops:

Canon EF-S 60mm Macro USM Lens f/2.8-f/32

Canon 85mm Telephoto Lens f/1.8-f/22

what s the f stop difference between them and what do they do?

Answer 1

The f-stop is a measurement of how open the aperture is. The aperture is essentially a circle that adjusts how much light comes into the camera. The lower the f-stop number the bigger the hole is, and thus more light.

When you look at a zoom lens you're given an f-stop range (like 3.5-5.6) that tells you the largest aperture you can get at each extreme of the zoom range. With a prime lens, like the ones you mentioned, it's telling you the maximum and minimum aperture size.

If you want good background blur (shallow depth of field) you want a large aperture (small f-stop). In the comparisson of those two lenses the 85mm opens to 1.8 while the 60mm only opens to 2.8. Therefore the 85mm has more potential to give you good background blur.

Answer 2

Most all lenses have a "depth of field" gage on them. As the F stop gets smaller, the depth of field gets smaller as well, so the f 1.8 lens will have a narrower depth when the lens is wide open. Thus by focusing on a close subject, the back ground will be more out of focus with the 1.8 lens than the 2.8. You can use the d.o.f gage to get maximum effect when you want to get most blurring of the background.