Even though it may be true that higher resolution mobile phone cameras have eroded the sales of compact digital cameras, there are still people to whom photography is a serious hobby, that want more than candid snapshots.

These people are the intended audience for this discussion of digital cameras with interchangeable lenses.

Interchangeable digital camera lenses, just as lenses for film cameras, are of three types: fixed focal length, variable focal length or zoom lenses, and special effects lenses.

Given that it is currently possible to get a decent digital camera that incorporates a 35x optical zoom factor (840 mm 35mm film camera equivalent), why consider carrying extra lenses or being caught with the wrong lens at the wrong time?

The short answer is image quality.

Digital cameras with interchangeable lenses usually possess a larger image sensor in the body of the camera than a compact, zoom lens camera.

In practical terms, this means that for the same resolution, the larger image sensor will produce a higher quality image. This is important for print purposes, where enlargements greater than 8×10 are desired and where it is desirable to capture extreme detail.

The large image sensor will also capture light better in low light situations.

Large sensors produce larger digital files, important for anyone who wants to manipulate photos with image editing software.

Assuming that these three benefits justify the decision to carry multiple lenses, let’s take a look at the different types and the purposes for each.

Fixed Focal Length Lenses

Single focal length lenses typically occupy the extremes, that is, they are very short or very long focal lengths.

A short length lens is ideal for pictures where it is advantageous to get as close as possible to the subject, such as portraits or large groups where excessive distance from the subject would result in poor ambient lighting or exceed the capabilities of flash photography.

The other extreme are super telephoto lenses, generally focal lengths in excess of 1000 mm. in 35mm. equivalent.

Even with image stabilization, tripods are in order; size and weight make hand held shooting problematic.

One of the prime uses for extreme telephoto lenses is wildlife photography where the wariness or small size of the subject means that there will be a lot of distance between the photographer and the subject.

Variable or Zoom Lenses

These offer a creative opportunity. The photographer can take the same shot at various focal lengths and check later to see which shot produced the best result.

The compromise presented by the flexibility of the zoom lens is that it often seems as though the wide angle setting is not quite wide enough, and the telephoto setting falls a little short of adequate.

Still, zooms are very popular for their ability to adequately cover everything that falls in between short and long fixed focal length lenses. Something that offers focal lengths between 50 and 200 mm. will suffice for at least 80% of the time. Most digital camera best buys that come with a lens, and not just the camera body, will supply a variable zoom lens as part of a package.

Special Effect Lenses

This category includes things like the fish-eye lens, macro soft focus, infrared and ultraviolet, and stereoscopic lenses.

They are limited to very specific instances. Whether or not to own these types of lenses would be determined by whether or not they would be used often enough to justify their cost.

Sony digital cameras offer a vast selection of lenses for typically encountered purposes, as well as lenses for those rare occasions where a specialized dedicated lens will produce unique results.

Source by Steve Baptiste