Howard----perfact. Thanks Richard ----- Original Message ----- From: "howard" <home@xxxxxxxxxxxxxxxxx> To: "List for Photo/Imaging Educators - Professionals - Students" <photoforum@xxxxxxxxxxxxxxxxxxxxxx> Sent: Friday, September 30, 2005 1:57 PM Subject: Re: Exposure question > Richard Cooper --- Cooper investment recovery inc wrote: > > > If I set my digital camera to f/8 and meter the light and the meter > > gived me a shutter of 1/250-------by increasing the shutter to 1/500 > > less light will be recorded and the image will be darker? > > Is this correct and is there any summary reading of exposure settings > > available? > > Thanks > > Richard Cooper > > Yes Richard, your image will be darker. If you are using Photoshop > Elements 3 or CS, you will see in the histogram of levels that there are > fewer pixels in the light end. > > Equivalent exposures can be thought of in a table: > > Using your metered values, these are all the same exposures: > > Aperture Shutter speed > f/2.8 1/2000 > f/4 1/1000 > f/5.6 1/500 > f/8 1/250 > f/11 1/125 > f/16 1/60 > f/22 1/30 > > I like to think of the changes in stops, and that is how I teach it. > 1 stop is either a doubling of the light coming onto the sensor - or a > halving of it. > > If the aperture INCREASES by 1 stop e.g. f/8 => f/5.6 > then the shutter speed must DECREASE by 1 stop, e.g 1/250 => 1/500 > > You can quickly work out alternative sequences this way. > > You can also think of ISO changes in the same way e.g. > If ISO changes from 100 to 200, the film is twice (100%) as fast so it > is 1 stop faster > > THUS at 100 ISO > f/8 1/250 > at 200 ISO becomes > f/11 1/250 > f/8 1/500 > f/5.6 1/1000 > etc. > > However, I'm sure someone else will have another way of expressing it! > > Howard > > >
