Incidental light metering is so simple to use and effective in producing a very large percentage of well exposed results in such a diverse range of lighting conditions that many people who are new to it and for a long time have used reflected light metering have difficulty in understanding that you can forget The Zone System and tone placement and that the only things you have to do to modify the incidental reading taken on negative film is if the subject is predominantly dark give half a stop more exposure, or if light overall half a stop less, and the reverse with transparency films because they are positive films. A very small amount of subjects are not suitable for incidental metering like trans- illuminated things like stained glass windows and distant landscapes where reflected metering is of more use