Your camera kit usually comes with lenses, the cheaper the camera kit, the cheaper the lenses … accept that as a fact!
If you are serious about your photography, I would suggest you drop those lenses off, and go shopping for a lens that fits your needs. To help you identify the lens that most suits your style, I would suggest reading through this post & probably doing some more research on the keywords that I shall mention.
Lenses would typically fall under one of 5 major categories; Wide Angle, Standard, Medium Telephoto, Telephoto, & Specialist.
Wide Angel lenses (10-35mm) are usually used to capture landscapes, cityscapes, architecture & a group of people.
Standard lenses (35-70mm) are usually used for street photography, as well as photojournalism, as they capture images at a range equivalent to the human’s eye.
Medium Telephoto lenses (80-135mm) are best suited for portraiture, as they compress the image & flatter the subject.
Telephoto lenses (135-500mm) are best suited for sports & wildlife photography, as they allow you to capture images of distant subjects.
Specialized lenses; such as the macro lenses allow you to focus at close range, as well as magnify the subject. Another specialized lens is the fisheye lens (4.5-16mm), which allow you a view of up to 180 degrees! A third specialized lens would be the tilt-shift lens, which allows you to fix perspective issues & usually used in architecture photography.
Alright, so now that we know the different types of lenses, what makes a lens good or bad? There are many attributes that affect the outcome of the above question, however I will restrict my response to the following; build quality, glass quality, sharpness, speed, distortion & chromatic aberration.
Build quality is simply the measure of durability of said lens; whether it withstands shocks, whether it is weather sealed, whether it feels right & smooth in your hands.
Glass quality is the measure of the quality of glass used to build the lens, glass elements & groups. Usually, lens glass quality coupled with your camera’s sensor type should be sufficient to let you know how good your image quality would be.
Sharpness, is directly related to glass quality; the better the glass, the sharper your images. This is something that no post-processing software can fix, so make sure you read reviews on your lens before you purchase & ensure it is as sharp as you would need.
Speed can be identified by a lens’s maximum aperture (f). The wider the aperture (smaller f number), the faster the lens. There are many advantages of using fast lenses, most important of those are for low light shooting, ‘bokeh effect’ & shallow depth of field. Kindly note that the faster the lens, the more expensive it would be. (The fastest commercial lenses are at f1.2, however most portrait lenses come at f2.8. Also please note that the wider the aperture, the more difficult it would be to get the focus right)
Distortion (mainly barrel distortion) has always been linked to wide angle lenses, as they create a barrel-like effect in your images. However, many software have now managed to reduce its effect.
Chromatic aberration are the fringes of color that show up along the edges separating bright & dark. As much as it affects our images, you’d be glad to know some software are capable of identifying your lens and correcting/reducing this aberration automatically.
One last thing to note is that DSLRs come in two different formats; Crop sensors & full frames. As such, Canon for instance, makes two different sets of lenses, EF-S (for crop sensors) & EF (suitable for both crop & full frame sensors). If you are using a lens on a crop sensor, note that the focal length of the lens will not be the same as marketed (e.g. an EF 100mm lens would actually translate to 160mm on a crop sensor).