Photography Techniques

Focal length of the lenses used in digital camera – its importance

aberrations
Written by Dave Peterson

Focal length of the lenses used in digital camera – its importance

aberrationsFocal length of the lenses used in digital camera – its importance! The creative control of digital photography is possible once you understand various camera lenses and their influence on image quality, focal length, aperture and perspective. Lenses of camera actually consist of several lens elements. Each element is there to direct the rays of light incident on it in such a manner that image as accurate as possible is recreated on the digital sensor. The ultimate aim is to utilize the less expensive and minimum elements keeping aberrations to the minimum level.

Optical aberrations results when points are not translated as it is in the image after going through the lens thus causing reduction in contrast, image blurring or colors misalignment. Lenses may cause radial decrease in image brightness as well as distortion. Every lens has some degree of problems stated above. The focal length in case of an optical system is the measure of how it converges or diverges, the light incident on it.

Focal length of the lenses used in digital camera – its importance

aberrationsA system having focal length of smaller value bends the rays of incident light more when compared with system having larger focal length and hence brings the rays of light to a point at a shorter distance. In photography longer focal length means lower optical power, wider view angle and bigger magnification. On the other hand shorter focal length means higher optical power and wider angle of view. Selection of lens for your camera is as difficult as selecting camera.

The life span of camera is couple of years only. As there is lots of development in the camera models, you need to change camera every 4 to 5 years if you want to have best quality photographs. A properly handled lens on the other hand will have longer life than the camera, so a good lens is an investment for long run. Also the light while reaching camera’s sensor passes through the lens. Bad image quality results when low quality lens is placed on high quality camera. However a good lens on an entry level camera can still bring better results.

Focal length of the lenses used in digital camera – its importance

Different lenses distort or compress the view. A wide angle lens makes the distances look greater than what they actually are and distorts the view. While the telephoto lens makes the view compressed and show the far away object at distance closer than the actual one. Many people feel that focal length influence the perspective of an image but perspective gets changed with location of camera from the subject.

aberrationsHowever same subject if shot with telephoto and wide angle lens will change the perspective of the image taken by the camera since you will have to move closer or away from the subject. In such a situation wide lens stretches perspective while telephoto lens flattens the perspective.

Camera shake impact is more visible in cameras with telephoto lenses. Wide angle lenses have lesser effect of flare. The easiness of getting a sharp handheld photograph depends on focal length of lens used in camera. To reduce burring as a result of shaky hands, exposure time in camera using longer focal lengths should be shorter.

There are two types of lenses namely prime and zoom. Next section of tutorials will explain these types of lenses in detail.

Tutorial Twenty Seven  –Prime verses Zoom lens – Many pros and cons of the two for quality photography

Tutorial Twenty Five  –Zoom and perspective – How they affect the quality photography?

About the author

Dave Peterson

Dave Peterson
Passion for adventure and sharing his life long journey with as many others as possible.

"What lies behind us and what lies before us are tiny matters compared to what lies within us." HENRY S. HASKINS

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