Digital camera lenses

[1ARMEDBANDIT]

Can someone please help? I got the chance to buy a lens for my NIKON D50 SLR digital camera, the lens is a NIKON AF 70-300MM. What is the optical zoom on this? I need someone to explain the numbers. I see tons of reviews and write-ups but it don`t mean a thing to me. Will I be able to use it as a zoom lens?
Also I see compact digital cameras with zoom capabilities of X3, X5, X10 etc, where does this 70-300 fit in among those?
Thank you.

[Buenchico]

The focal lengths of digital camera lenses aren't true 'scientific' figures. They're based upon the focal lengths of lenses for 35mm (film) cameras, which will do the same job.

A 'standard' lens on a basic non-zoomable camera will have a focal length of around 40mm to 50mm. Lenses with shorter focal lengths (e.g. 30mm) are 'wide angle' lenses. (Really short focal lengths, e.g. 20mm, are 'fish-eye' lenses).

70mm is a 'short telephoto' lens. (i.e. the image will be slightly larger than with a 'standard' lens). 300mm is a 'long telephoto' lens. (i.e. the image will be a lot bigger than with a 'standard' lens).

Zoom lenses can be adjusted to any focal length from their minimum (70mm in your case) to their maximum (300mm). The 'optical zoom' magnification factor (e.g. x3, x5, etc) doesn't, in itself, tell you anything about the actual focal lengths at either end of the range. For example a lens which could go from a 30mm wide-angle view to a 150mm 'mid-telephoto' view would have a magnification factor x5 ('cos 150 is 5 times greater than 30). But a lens which could go from a 'short telephoto' 70mm to a 'long telephoto' 350mm would also have a x5 magnification factor.

Since 300 is about 4.3 times 70, the lens you refer to has an 'optical zoom' of roughly x4.3. What's really important though is that it goes from 'short telephoto' to 'long telephoto'. So it would be great for getting close-up shots of fairly distant objects but totally useless if you want to have a wide-angle capability.

Chris

[1ARMEDBANDIT]

Hi Buenchico,
That`s brilliant! Much appreciated.
Many thanks.

[dundurn]

One other thing to say is that the D50 isn't a "full frame" camera,so the focal length figures you have need to be multiplied by approx 1.5. The 70 to 300mm figures are based on what would be achieved with an SLR camera using 35mm film. Effectively you have a 105mm to 450mm lens.