Beginner tutorial about Dslr camera lenses
Focal length is usually indicated in the lens name, for example 18-55mm, this is a zoom lens between 18-55mm focal length, or 50mm on the picture above.
On smaller not full frame cameras:
0-30mm wide angle
400-800mm super telephoto.
Brigntness is the second number, for example f/3.5-5.6. What does it mean? In the wide end f/3.5 (smaller number is the brighter lens) long end is (f/5.6), some time they omit the “/” sign, just talk like f2.8,f4,f5.6. 1:1.4 on the picture above, f1.4 lens which is quite bright
f2.8 and below – bright lenses
f2.8-f4 average lenses
f5.6 little darker lenses usually telephoto
Prime or zoom lenses
Prime lenses are fixed, no zooming. Either wide angle, normal or telephoto.
If you buy a prime lens the good focal length (for you) is essential.
Zoom lenses are more versatile, and more popular. Usually prime lenses are brighter, smaller and has better image quality. But it is not so simple, there are very bad prime lenses and very good zoom lenses as well.
Minimal focusing distance
There is usually a number sometimes written on the lens barell, which is the closest distance the lens can focus(can make sharp images). You can go closer but the image will not be totally sharp. Usually for wide angle lenses it is between 25-50cm, for longer telephoto lenses is 1.5-3m. Why this is so important ? Because in many cases you want to work at the closest distance, for example for macro or if you want to blur the bacground, or in product photography.
General purpose lens
This lens is needed for most phtography.
Recommended lenses for Canon dslr cameras
kit lens: Canon 18-55 is Stm
Tamron 17-50 f/2.8(non-is) the best value lens for Canon available with small size, constant f/2.8 brightness
Canon 17-55 is a hair better than the Tamron but much more expensive with same parameters,
Canon 15-85 is, more versatile than the first two
Recommended lenses for Nikon dslr cameras
kit lens: Nikon 18-55 vr or 18-105 vr
The Nikon 16-85 Vr is a very nice lens if you have the budget for it as a general purpose lens.
Tamron 17-50 f/2.8 (non-is)
Nikon 35/1.8 the best value Nikon lens available with great brightness