The F-Stop Exposure Calculator is designed to help darkroom printers calculate exposure times when adjusting the amount of light in their prints. By inputting your base exposure time (the time you initially exposed your print), the calculator will provide the correct exposure times for different f-stop adjustments. You can select increments like 1/2 stop, 1/3 stop, 1/4 stop, and more. This helps you make precise adjustments to your exposure time, whether you're dodging or burning parts of the image, or adjusting exposure to achieve the desired result. It simplifies the process by showing you the exact time changes based on your input in f-stops, saving time and improving accuracy in your darkroom workflow.

The F-Stop Exposure Calculator helps you think in terms of exposure ratios rather than just seconds. Instead of measuring exposure in raw seconds, you’re adjusting exposure in stops of light (e.g., doubling the light or halving it). This system allows you to make more controlled, intuitive exposure adjustments, especially when dodging and burning parts of your print.

With the F-Stop Exposure Calculator, you can scale your exposure adjustments up or down using increments like half stops, quarter stops, or even 1/12 stops. This flexibility gives you the precision you need to adjust exposure for any part of your image without relying on trial and error. Whether you need a subtle nudge or a larger change, the calculator guides you through the exact times for each adjustment.

The calculator is perfect for dodging and burning because it allows you to see the exact exposure changes for specific areas. You can make small, precise adjustments based on f-stop increments, helping you to lighten or darken areas exactly as needed. Whether you’re working with highlights or shadows, the calculator gives you the precision to control light effectively.

By using the F-Stop Exposure Calculator to create a reference set of test prints (ranging from underexposed to overexposed), you’ll start to recognize how different exposure adjustments affect your print. Over time, you’ll build a visual reference that helps guide your decisions when making new prints, dodging, and burning.

F-stop printing allows you to fine-tune your exposure to get the exact tonal qualities you want. It’s a system based on ratios, which makes it more flexible than simply adding or subtracting seconds. Whether you’re adjusting shadows, highlights, or midtones, f-stop printing lets you get precise control over how light affects your final print.

Yes, once you've calculated the exposure settings, you can easily download a PDF version of your results. This can be saved for reference or printed out for use in your darkroom workflow, making it easy to keep track of settings for future prints.

Yes, the F-Stop Exposure Calculator is completely free and available for all film photographers and darkroom printers. Whether you're working with black-and-white or color film, this tool provides the precision and ease you need to enhance your darkroom printing process.

Dodge and Burn mode in the F-Stop Exposure Calculator helps you make exposure adjustments based on the difference between the base exposure and your desired change. In this mode, the calculator shows you the delta (the difference in exposure time) rather than just the full exposure time. This is especially useful for dodging (lightening) or burning (darkening) specific areas of your print. When you toggle on Dodge and Burn mode, it allows you to see exactly how much more or less exposure is needed to achieve your desired effect, giving you better control and precision for local adjustments in your prints. Instead of guessing or using trial and error, you get specific values that help you make informed, repeatable decisions when modifying exposure in different areas of your image.

It was created by Matthew Koller for the Unlock the Darkroom course and darkroom printing community — to help photographers spend less time test-strip-guessing and more time making beautiful black and white prints.