Archived posting to the Leica Users Group, 2002/07/12
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Ted, The guide number is usually given for a film speed of 100 ASA and is nothing more than the the f stop, multiplied by the distance (in meters !) by which the light of the flash will be able to light the subject. My Metz CT60 has a guide number of 60 (surprise !) and can get as far as 30 meters with f2, or 15 with f4, and so on. I suppose your friend's flashlight will list the guide number in feet, but the principle should still be the same. Using a manual flashlight goes like this : - - focus on the subject - - check the distance scale on the lens - - divide the guide number by the distance, this should give the f stop needed for a correct exposure. I remember Nikon having a 45 mm GN (guide number) lens, with an extra ring to set the guide number of the flashlight you used. The aperture was coupled with the focussing ring, so that it would be adjusted automatically. Johan Doumont > Hi folks, > > This is right off the wall ancient need to learn it over again. > > A chap down the street called and asked me how to use the guide number on > the flash he has? > > Well OK I thought I knew.... however that was 45 years ago when the flash of > the day had guide numbers. Even then I had trouble figuring that stuff out, > then I discovered photo life was much easier when you didn't use flash and > go available light. ;-) > > Besides any flash I used over the years has always been something automatic > no brainer thing. So please help me with a very simple way to explain this > guide number and how to make it work with whatever flash and camera is he > has. > > thanks guys and gals. > ted > > > > > > > -- > To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html > - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html