Binocular focus to camera zoom conversion

[guffhoover]

I am looking to get my first lense for my 450D. The lense that came with the camera is ok for portraits but i would like a longer zoom to start with and possibly a wide angle lense later on in the year.

I would really like the new lense to have atleast the same range as my binoculars but i am finding it hard to convert the binoculars focussing range into 'mm' terms for a zoom lense.

The binoculars have 8x40 8.2o written on them. Can this information be used to calculate a zoom range for a camera lense?

Any additional comments on a good lense and good place to buy from would be appreciated; unfortunately i can't afford cannon so i would be looking at tamron et al.

[Major Bloodnok]

Your binoculars have a magnification factor of 8, so you want a lens that has 1/8th of the view angle of a standard lens (45 degrees), so you want a lens that gives a diagonal angle of about 6 degrees, which, for the 450D, Photobuddy works out to be 255mm. Note that this only applies to cameras having the same size sensor as the 450D (22x14 mm). For other sizes, you need a different focal length to achieve the same magnification - e.g. for a 35mm camera (full frame sensor or film), you'd need a 400mm lens

[guffhoover]

Major Bloodnok said:

Your binoculars have a magnification factor of 8, so you want a lens that has 1/8th of the view angle of a standard lens (45 degrees), so you want a lens that gives a diagonal angle of about 6 degrees, which, for the 450D, Photobuddy works out to be 255mm. Note that this only applies to cameras having the same size sensor as the 450D (22x14 mm). For other sizes, you need a different focal length to achieve the same magnification - e.g. for a 35mm camera (full frame sensor or film), you'd need a 400mm lens

Thanks for that; not sure i understand it all but 255mm sounds good. Thanks again

[Major Bloodnok]

I think that I've got that right, but to be safe, you might want to take the binoculars and camera to your local photo shop and try out a 70-300 zoom. Set it at 250mm and compare to the binoculars. Just remember, you're comparing the apparent size of objects, not the amount you can see, since the lens will probably have a much smaller field of view than the binoculars.