Originally Posted by
lensman57
It might well do but it is meaningless unless it is compared to the FOV of the human eye in which case it has to be expressed in another way. A 35 mm film camera ( full frame digital nowadays ) has a diagonal of 42.4 mm which covers an angle of view ( horizontal ) of about 46 degrees. This is approximately the angle of view of a human eye. That is why in photographic terms it is called " normal " lens. The popular 50mm lenses are in fact slightly long and not " normal " and the 35 mm is as you know a wide angle. They are probably referring to the focal length of the lens being 5x the diagonal of the sensor therefore in effect giving you a 5X the normal lens for this particular sensor. But unless this is stated clearly it could be anything, 5X the focal length of the compound eye of a fly, unless they clarify it. It would have been better to either express this in terms of FOV or with some reference to a 35 mm camera for example the lens being equivalent to a 200 mm telephoto in relative terms as this is easier for most people to relate to. The other meaningless term that is widely used in both terrestrial and astronomical scopes sales blurb is magnification, but it is beyond the scope of this thread to discuss why.
Kind Regards,
A.G
I have no doubt that you know what you're talking about, but can you explain to this layman, in simple terms, how it is that I can look e.g. at the moon through one naked eye and with the other through an 8X telescope, I can see an image with a very close approximation to 8 times larger?
Happy Shooting!! Paul.
"We cannot solve our problems with the same thinking that we used when we created them" - Albert Einstein.