Hi All, The main reason the lenses cost more are the following: The fast lenses use more exotic elements inside Flourite, UD, etc The fast lenses are often made of extremely high grade and light weight metals titanium, magnesium etc. Also they often contain high end and exotic composite materials. And tougher and better electronics, more switches gears and rings. The lenses are also more expensive to make. Fast glass does not sell real well, meaning a given camera company will sell loads more tele zooms than it will 400 2.8. So the price is higher to pay the R&D, and manufacturing costs with a small profit built in. Happy holidaze, Les > Kevin, there are a lot of factors that go into > lens costs. Lets look at a > few things in layman's terms. A lens with a > max opening of F5.6 has more > depth of field than a lens of F2.8. The > reason to buy a fast lens is to > shoot it wide open typically. Focusing > errors, lens aberrations > and distortions show up in lens when they are > either shot wide open or > stopped down to their maximum. Thats why > F8-F11 are considered the sweet > spots in lenses. Most lenses are turned to > produce the best picture at > those F stops. > > The F2.8 lenses and faster have to be tuned for > a wider range of > apertures. Lens elements must meet much more > stringent quality > controls. The lens elements are bigger and > harder to make. There are > typically more elements to correct for various > distortions along the > way. The heaver glass needs more heavy duty > gears and motors to > auto-focus them. It all adds up to a more > expensive lens. > > Hope that helps explain it.... > > > Happy Holidays, > Rob > -- > Rob Miracle > Photographic Miracles > 203 Carpenter Brook Dr. > Cary, NC 27519 > http://www.photo-miracles.com > >
