LARGE FORMAT CAMERAS

There are various types of Large Format cameras available. Here I am using a Cambo brand. When you use a large format camera, you need to remember to allow for what is known as RECIPROCITY FAILURE

Reciprocity failure becomes an issue when using large format cameras with bellows, since the light must travel further - or for longer to give the correct exposure to your image. Reciprocity failure can also be an issue in dim lighting or when shooting at night. It is better to widen you aperture if possible to allow for this, however, I wanted to take my images using a very shallow depth of field - hence the large distance of the bellows, and a very shallow depth of field using f5.6 to get the right effect. In order to establish the number of extra stops - (which in my case translated to extra seconds rather than altering my aperture) it was necessary to use a device known as an EXPOSURE CALCULATOR - SEE STRIP BELOW CAMERA IMAGE
The Exposure calculator is used alongside a target, which is placed on the subject. Once focused, the strip is placed on the viewfinder (back plate) and the distance measured which then tells you how many stops need to be added or removed.