Exposure Calculator An exposure calculator is basically a film positive that comes with five or more identical images including fine lines and dots. Using our best guess starting point exposure times, we double that time and expose the film onto a screen, and wash out as normal. After the screen is complete, hold it up to a light and compare the different images. The one that is exposed the best, where the image looks the most crisp, is our target. A formula under that image will tell us our ideal exposure time.
Exposure calculators are available from all emulsion manufacturers and your local supplier might give you this exposure film for free.