Hi! I understand your point quite well now. I liked the term "funneled down" that you used in your explanation.
Many thanks, Bill. With best regards, Ayash. On Mon, 1 Jul 2002, Bill D. Casselberry wrote: > Ayash Kanto Mukherjee wrote: > > > You are absolutely right in your point. I know that quite well. The > > f-number is defined as the ratio of focal length to the diameter of the > > aperture (Am I correct?). > > Yep - so the light-gathering of the bigger front element will > get "funneled down" to the same as the f4 when stopped down to f4 > > > But I am talking about the preliminary intensity of light reaching > > the film plane because of the wider diameter of the front element > > in the case of 50 mm f/1.4. > > The intensity of the source doesn't enter into things. Unless > it differs between the time you use the f1.4 and the time you > use the f4, an autometering system will give the same shutter > speed at any given f-stop. Things do look brighter in the > viewfinder w/ the f1.4, but when stopped down this disappears. > > Bill > > --------------------------------------------------------- > Bill D. Casselberry ; Photography on the Oregon Coast > > http://www.orednet.org/~bcasselb > [EMAIL PROTECTED] > --------------------------------------------------------- > - > This message is from the Pentax-Discuss Mail List. To unsubscribe, > go to http://www.pdml.net and follow the directions. Don't forget to > visit the Pentax Users' Gallery at http://pug.komkon.org . - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
