Archived posting to the Leica Users Group, 1998/08/07
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Dominique wrote: >How do you explain with the laws of optics that a 2X-converter behind, say, >a 2/180, gives an optical system with an aperture of 1:4 ? If Osterloh was >right, we shouldn't have that result. The quote from Osterloh that you posted didn't touch upon this in any way. The reduction of aperture ratio is based purely on the fact that since you now have an optical system with a focal length that is twice as long as the original, and you have the same entrance pupil, the f number or aperture ratio is now twice as large; ie, you lose two stops. This has nothing to do, in any way, with the quality of the image that results. * Henning J. Wulff /|\ Wulff Photography & Design /###\ mailto:henningw@archiphoto.com |[ ]| http://www.archiphoto.com