mm to Zoom times ??

How many times Zoom is the EF 100-400mm f/4.5-5.6L IS USM ?

or how do i work out what times zoom a lens is from mm

THANKS

--
http://www.pbase.com/r055

Simply take the maximum divided by the minimum, or 400/100 = 4X.

Now, if you're looking for the actual "magnification" of the lens that gets a bit more tricky as those figures are based relative to life-size. The 100-400 is probably something like .20. For the actual magnification you need to check the specs on the Canon website or Canon Museum as those numbers will be different for each lens.

R055 said:

How many times Zoom is the EF 100-400mm f/4.5-5.6L IS USM ?

or how do i work out what times zoom a lens is from mm

THANKS

--
http://www.pbase.com/r055

Click to expand...

Right - that's all you can do. The 100-400 is a 4X zoom.

When a camera is advertised as having a nnX zoom lens, that's really a measure of its versatility, not its maximum focal length.

A 'normal' lens has a focal length somewhere around 50mm, so you might reasonably expect a camera advertised as having a 2x zoom to cover the range 50-100mm. However, It might well instead cover 25-50mm, or 40-80mm. There's no way to tell without more information.

Andy.

John-G said:

Simply take the maximum divided by the minimum, or 400/100 = 4X.

Click to expand...

R055 said:

How many times Zoom is the EF 100-400mm f/4.5-5.6L IS USM ?

or how do i work out what times zoom a lens is from mm

Click to expand...

50mm is considered "normal" (e.g., for a 35mm format, it provides roughtly the same perspective and magnification as the human eye). Thus, 50mm is generally considered to be a magnification of 1x (equality). So 400mm is 8x magnification.

Cheers,
Chris

--
My photo gallery: http://www.cawtech.com/~caw/PhotoGallery/
My PhotoSIG page: http://www.photosig.com/viewuser.php?id=37120

Chris is right.

But be carefull in beleiving ads from camera companies. The marketers from all companies are just saying it is a 4 times zoom, so this refers to 100-400 mm as well as to 20-80 mm and any other combination where the factor is 4.
Regards -
Helmut

Christopher A. Wichura said:

R055 said:

How many times Zoom is the EF 100-400mm f/4.5-5.6L IS USM ?

or how do i work out what times zoom a lens is from mm

Click to expand...

50mm is considered "normal" (e.g., for a 35mm format, it provides
roughtly the same perspective and magnification as the human eye).
Thus, 50mm is generally considered to be a magnification of 1x
(equality). So 400mm is 8x magnification.

Cheers,
Chris

--
My photo gallery: http://www.cawtech.com/~caw/PhotoGallery/
My PhotoSIG page: http://www.photosig.com/viewuser.php?id=37120

Click to expand...

R055103667 said:

How many times Zoom is the EF 100-400mm f/4.5-5.6L IS USM ?

or how do i work out what times zoom a lens is from mm

THANKS

Click to expand...

I think you're coming from digital P&S cameras' world which always talk about X times zoom..

Usually these cameras have a x3 optical zoom which is most of time equivalent to 35mm-105mm or 28mm-85mm

If you want to compare the 100-400 to that, it will give you a zoom which covers x3 to x11

I hope i'm clear for you.. and i'm sorry about purists which will blame me of that non photographic answer but i presume that's the answer you wanted

THANKS !! thats cleared that one up for me. puts thumb up