Archived posting to the Leica Users Group, 2000/03/07
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> The surface of a circle is pi x radius squared. I don't have > lenses at > hand, but roughly, the putative radius of a 50mm f/1.4 lens > is 17.86mm, > that of an f/1.5 lens is 16.66mm. Squaring these, the ratio > is 318.9:277.56. > > Reducing this gives 1.14, or 1 1/7. > > Mayhaps my math is way off? > > Marc Hi Marc, I just sent a post about f-stops. Rereading your post, I realise I understand f-stops differently. The surface difference between 1.4 and 1.5 may be 14%. However, that does not mean 0,14 f-stop. 100% more light translates to 1 f-stop difference. 300% more light translates to 2 f-stops difference (not 3). Am I correct here? Rick Garrelfs ================================================== The information contained in this message may be confidential and is intended to be exclusively for the addressee. Should you receive this message unrightfully, please do not use the contents herein and notify the sender immediately by return e-mail. ==================================================