What do the numbers describing the lenses mean? For example 70-100?

Question

Please be as detailed as possible.. and if you know of a website that explains this type of thing about cameras that would be helpful, thanks!

Answer 1

That number is the focal length of the lens. For example, 70-100 mm means that the focal length of that lens varies between 70mm and 100mm. In other words, that particular lens is a zoom lens whose focal length ranges between 70mm and 100mm. Now, 35mm is considered to be the standard focal length for a digital camera. Any length below 35mm can be considered a wide angle and any length above 35mm can be considered a telephoto. A wide angle lens includes more of a scene in the picture frame and has more depth of field, a telephoto lens magnifies far away objects, but in order to do so, it will leave more of a scene out of the picture frame, and it has less depth of field (depth of field meaning the parts in the picture that are sharply focused). Pictures taken with wide angle lenses usually show curvilinear distortions, the most extreme one being the so-called "fish-eye". Some of these effects are cool, though, and generally wide angles are great for landcapes and panoramic views. Telephoto lenses are better in situations where you can't get close to the subject.

But a picture is worth more than 1000 words, so just look at the example here:
http://www.usa.canon.com/html/eflenses/lens101/focallength/index.html
It's the same scene viewed through different focal length lenses.

Answer 2

The 70-200 telephoto lense operates in this manner; The closest lens takes photos at a minimum of 70 milimeters, which is approaching portrait quality. A normal lense would be 50 mm, which gives you a good range for taking pictures. The largest number, is 200 mm, which is a telephoto setting able to bring in images at a distance. This is a decent telephoto range but will not deliver you shots like you see of New York Harbor at the 4th of July. Those lenses are $10,000 plus and are made specifically for professional photographers. You might look for a website by Kodak, Canon or Nikon. They can answer basic questions. If you need more information, check for community college classes, or Nikon School which travels around the country. Good luck!

Answer 3

Those numbers refer to the distance (in millimeters) between the glass at the end of the lense (not the front) and the focal piece in the middle of the lense. That's putting it pretty loosely also.

Answer 4

The Cat nailed this answer. Listen to her.

Answer 5

How strong you eye is!