Archived posting to the Leica Users Group, 1999/07/28
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Jean-Claude Berger wrote: > > Hi Mark, > > A T-stop does not represent a diameter. It's the effective > transmission of the lens, that is the amount of light it let pass > through it. Of course, it's a value always inferior to the > F-stop. With a coated lens, the T-stop is about 98% of the > F-stop. With an uncoated one, it can be as low as 30% depending > on the lighting conditions. > > All the best. > > -- > Jean-Claude Berger (jcberger@jcberger.com) > Systems and RDBMS consultant (MCSE) > Lyon, France > http://www.jcberger.com > > > I imagine a T stop would not represent a relationship > > but a fixed diameter. > > Mark Rabiner > > T stops were a cinematography thing until recently I think and cameras at day one. Getting a Blad looked at for free at the camera store today the guy ahead of me having all his chrome Blad lenses cleaned turned out to be my Photography teacher who tried to teaching me a bunch of this Math stuff, Circle of confusion and so on in 1976. I arragantly expelled it having been doing darkroom work since the age of 13 in 1965 and I thought I knew everything that was worth knowing. I flattered him by remembering his story about how his wife made him get a separate water heater for his darkroom. Kodak makes a wheel for lots of this stuff but his information handouts came in handy for years for me. I wish I still had them. I even had a few formula's memorized. When did pocket calculators come in? Mark Rabiner