PHFX.COM | tools - frameAnd Focus

2024 June Update
I've spent a considerable amount of time updating my depth of field calculator with some new features as well as more customizable options. It's been my goal to modernize depth of field calculations with more relevance to the acquistion system, rather than a rough estimation based on image plane, viewing medium, reproduction ratios, and viewing distances. This tool can now do both, but "photosite based" is the best approximation in the modern age. This research has been ongong since the 2000s for me. However, a recent collaborative effort with SMPTE, AMPAS, and the ASC has inspired mind numbing experimentation, research, and new code development. Thanks to David Stump, ASC and Snehal Patel for wrangling me into that. The results of that test shoot and about a dozen other test shoots since has produced these results.

Introduction
Welcome to my hopefully useful Depth of Field Calculator. This particular tool will generate a Depth of Field Table for a given Camera and Format, Focal Length, and Subject Distance. The table is generated in 1 f/stop increments based on your settings and is meant to use as a useful guide to assist in tricky framing conditions where you may be attempting to get a whole subject or subjects in focus at a certain distance. This will point you in the right direction to discover what approximate T-Stop or f/stop you will need to create that frame. Additionally, I have provided some diffraction notes if you are looking to avoid or rely on the impact of the slight visible softening of the image as you stop down the image.

Warning! Precision versus Practicality The formulas used here are indeed acurate, but the real world unfortunately provides an insane amount of variables considering the wide variety of imaging systems, optical path variance, different lens designs, innacuracey of focus scales or iris scales, telecentricity, knowing the actual focal length at a given focus distance, human related variables, and more. With that known, I promote a practical over precision based logic for professional image makers. With that consideration, my calculations work within a margin of error that I find acceptable/reasonable. I've conducted significant tests across different imaging systems and a great deal of lenses in a fairly controlled manner to verify my results.