Focal Length discussion

[imcarm]

Can anyone put me out of my misery regarding zoom lenses and focal length as I'm somewhat confused.

I currently own a Samsung Pro815 (Fixed lense) which has 15x optical zoom ( 7.2-108 mm f2.2-4.6 (35mm equivalent 28-420mm))

What I need to know is compared to a say Canon 100 - 400 USM lens should I be looking at the 7.2-108mm or the 35mm equiv (28-420mm) rating?

Anyone know because I feel the maximum zoom on this camera is not getting as close as I expected.

See this shot I took last night for example:
http://i71.photobucket.com/albums/i1...6/SH101124.jpg

Exif:
<snip>
Focal length: 104.7mm (35mm equivalent: 420mm)

[richard plumb]

its probably simplest to bring everything to 35mm equivalent.

You say your Pro815 has an equivalent of 28-420 on a 35mm camera.

So on a full frame camera like a 5D, you'd get the same magnification with a 400mm lens.

On a 1.6 crop camera, you'd only need a 262mm lens to give you the same reach (262 x 1.6 = 420).

A 400mm lens on a 350d for example will give you a 35mm equivalent of 640mm.


thats just simple reach. It gets complicated when you include sensor size Vs field of view/perspective etc.

[imcarm]

Cheers Richard that's explained it

I'm sure I'm not the first to get confused by this, and probably not the last either