Photography means light drawing or drawing with light. The sensor/film in the camera is the light-sensitive surface that we draw on, it’s like a sheet of paper if you like. The camera is a pencil or pen with which we draw our drawings with light or photographs as they are commonly called. Light is the lead or ink with which we draw.
An underexposed photographic image is a bit like a sheet of paper with only faint lines or marks on it. An overexposed photographic image is a bit like a sheet of paper that is black with lines and marks on it. The trick is to let a combination of light, dark and shades between leave an image on the sensor/film that we call a photograph.
The photographer controls the ‘marks’ the camera makes on the sensor/film through the ISO, aperture and shutter speed settings on the camera its self.
As we are drawing with light we set the ISO setting on the camera first. The ISO setting sets the sensitivity of the sensor or the sensitivity of the film we are using to the brightness of the light we are going to work with. It is no use to the photographer if the sensor/film and the light brightness is miss-matched. If the light we are working in is bright daylight an ISO of 100 or 200 is a good point to start. If the light we are working in is a general shade or indoors an ISO of 400 or 800 is more inline. If the light that the photographer is working under is low light an ISO of 1600 or 3200 will be more appropriate.
Have a coffee break now.
By first matching the ISO to the lighting conditions, the photographer will have a fuller range of apertures and shutter speeds on the camera at hand to work with.
Aperture or f stops and shutter speeds work in tandem, they work together. For example, A photographer is working in the general shade at 400 ISO at f4 and shutter speed of 1/60 of a second and get a good exposure. The photographer can change to f5.6 and 1/30, by increasing the aperture by a stop and decreasing the speed of the shutter. The photographer will still get a good exposure but increase the depth of field and with the decrease of shutter speed will gain more movement in the photograph.
In a second example, the photographer could have changed from f4 and 1/60 by a stop to f2.8 and 1/125 and again get a good exposure but this time decrease the depth of field but increase the freezing of movement in the resulting photograph.
By understanding how ISO, aperture and shutter speed work together, the photographer is in a position of strength and can make a well-exposed picture with more of the depth of field and ‘movement’ aspects in mind.
The aperture of the camera is a static version of the human eye, I say static because the human eye adjusts subconsciously to the available light entering the eye. The aperture of the camera needs a conscious changing to adjust for the light entering the camera, thus it is static.
The photographer needs to decide what elements of the picture are going to have detail and what elements are going to remain in deep shadow or bright blow out. Unlike the human eye, the photographic picture cannot have both.
The skilful use of a handheld light metre or the in-camera light metre and a bit of practice will solidify this aspect of photography into your bedrock of photography theory…
This is an excerpt from the third session in the 18 one hour lessons of the Camera & Coffee Sessions, call John Robinson on +27836547789 to book a Zoom.us session with him