Karl Shah-Jenner <shahjen@iinet.net.au> writes: > so if we are considering an 85mm f3.5 lens we are talking of an aperture of > 24.3mm > so if we are considering an 85mm f1.4 lens we are talking of an aperture of > 61mm > > Imagine having to grind a precision lens that is more than twice the size of > it's smaller, slower counterpart and still maintain good optical > characteristics! Hmm, well, if the diameter is more than twice as big, that's more than _four_ times as much glass, even if the thickness doesn't increase, so realistically 6 to 8 times as much. If you're looking at the specs, you could consider price per gram of glass?? Brian Chandler ---------------- geo://Sano.Japan.Planet_3 Jigsaw puzzles from Japan at: http://imaginatorium.org/shop/
