Even if the number of megapixels is less on the sensor, but if the lens is of a superior quality, then the quality of the image is greatly enhanced. The lens is a very important part of a digital camera and should be understood fully to take better pictures. Most aim and shoot digital cameras have fixed lens but with digital SLRs changing lenses is possible, and should be actively pursued to get that right shot.

Broad classification of digital camera lens
Broadly, digital camera lens may be classified as fixed or removable.

• Fixed focal length lens - Here the camera lens is fixed. It does not change. You can get a close up shot by moving close to the subject. This type of lens is very good for snapshot cameras and are the most selling ones in the market of digital cameras. The advantage of this type of lens is the cost, weight, and speed. It has been seen the an inexpensive fixed lens can usually provide as good if not better results as a high-end zoom lens. Again, the fixed lenses have larger maximum aperture and so have a better light-gathering ability, than the fastest zoom lenses. This helps in critical low-light sports/theatre photography, and when the depth of field is shallow.

• Removable lens - These are featured in dSLRs. They are meant for professionals who understand which lens to choose for what task. It is a complex trade-off between image quality, lens speed, cost, size, and weight. Professionals, who understand the relationship between camera lenses and image quality, focal length, perspective, prime vs. zoom lenses, and aperture or f-number are ideally suited for this kind of removable or changeable lenses. Single Lens Reflex digital (dSLR) cameras accept a wide range of interchangeable lenses. With the same brand dSLR, the 35mm film SLR lenses may be compatible. Converter lenses are also available for many digital cameras as add-ons.

Optical zoom versus digital zoom
Zooming means coming closer (zooming in) or going away (zooming out) from the subject. Digital zoom lenses magnify an image 3X, 4X, 10X and more. This means that when zoomed the image is enlarged through interpolation; it is not actually zooming in. Digital zoom is not the same as optical zoom. An optical zoom is a true zoom, as its focal length extends and retracts. In an optical zoom, the lens itself magnifies the image without actually changing the focal length. In a digital zoom, the image is simply enlarged by interpolation.

Considerations for evaluating a digital camera SLR lens
• Is the general focus and sharpness good? Are details rendered nicely? Are the corners as sharp as the middle as you move to wider angles? How does the lens fare with wider apertures?

• At wide angles, does the lens vignette and produce a darkening of the corners and edges? While zooming to either extreme, is there barrel or pincushion distortion? Is there flaring at wide angles?

• Does the lens have provision for attachments like wide angle or telephoto lens? Does it have a threaded mount or a bayonet style mount? How expensive are the attachments?

• Is there electronic or manual zoom control? A manual zoom is preferable for speed and flexibility.

• How is the lens rated in the best digital camera consumer report? Is the digital camera review good?

While evaluating your lens, the type of shooting should be considered first. For sports or nature photography, a telephoto lens is better; for architectural or landscape photography, a wide-angle lens should be used; and for normal everyday shooting, a normal 50mm view is used or its equivalent for digital cameras.