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<blockquote data-quote="WayneF" data-source="post: 181707" data-attributes="member: 12496">Closest possibly could have two meanings..One might be how near can it focus, how close can I stand?&nbsp; 2 feet?&nbsp; 3 feet?But probably you refer to telephoto magnification, like looking in binoculars for example, to bring far things up closer.Not easy to explain, but cameras have a &quot;normal&quot; lens focal length, which give a &quot;normal&quot; view, comparable to the angular view that our eyes see.&nbsp;&nbsp; This is a focal length around the diagonal size of the sensor.But in practice, it works out to be about a 40 degree view.&nbsp; Humans have wider peripheral vision, but what we mostly look at is around a 40 degree view.On your D3100 DX camera, this &quot;normal&quot; focal length would be about 30mm.It takes a picture you may consider to be about your normal vision width, around a 40 degree view.&nbsp; Wider (shorter) is considered wide angle, and a more narrow view (longer) is telephoto.The 200 mm lens will be 200/30 = 6.7x longer, which will magnify objects 6.7x size (compared to the normal lens), which brings them up about 6.7x closer.&nbsp; On the DX camera, the effect will compare to looking in 6x binoculars.&nbsp; On a FX camera body, same lens would appear 1.5x less, or about 4.4x magnification (compared to that &quot;normal&quot; view of that FX camera).The 300 mm lens would 300/30 or 10x, or comparable to looking though 10x binoculars.&nbsp; Longer lenses magnify more.&nbsp; For DX cameras (D3100), you can compare their focal length to a 30mm &quot;normal&quot; lens.</blockquote>

[QUOTE="WayneF, post: 181707, member: 12496"] Closest possibly could have two meanings.. One might be how near can it focus, how close can I stand? 2 feet? 3 feet? But probably you refer to telephoto magnification, like looking in binoculars for example, to bring far things up closer. Not easy to explain, but cameras have a "normal" lens focal length, which give a "normal" view, comparable to the angular view that our eyes see. This is a focal length around the diagonal size of the sensor. But in practice, it works out to be about a 40 degree view. Humans have wider peripheral vision, but what we mostly look at is around a 40 degree view. On your D3100 DX camera, this "normal" focal length would be about 30mm. It takes a picture you may consider to be about your normal vision width, around a 40 degree view. Wider (shorter) is considered wide angle, and a more narrow view (longer) is telephoto. The 200 mm lens will be 200/30 = 6.7x longer, which will magnify objects 6.7x size (compared to the normal lens), which brings them up about 6.7x closer. On the DX camera, the effect will compare to looking in 6x binoculars. On a FX camera body, same lens would appear 1.5x less, or about 4.4x magnification (compared to that "normal" view of that FX camera). The 300 mm lens would 300/30 or 10x, or comparable to looking though 10x binoculars. Longer lenses magnify more. For DX cameras (D3100), you can compare their focal length to a 30mm "normal" lens. [/QUOTE]

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