I've recently been hired to take some extreme macro shots in a controlled lab environment. To automate the focus stacking process necessary for such small detail work I've invested in a Stackshot by Cognisys Inc. However, in order to use this process effectively, it's important to know what depth of field you are getting at various apertures at differing magnification levels. There are a lot of spreadsheets out there that can help with this but I couldn't find any that suited my exact needs, so I've created one and made it available here: Depth of field calculator for macro photography. This spreadsheet is specifically for Canon cameras with a full frame sensor using various Canon lenses and I'll be adding to it as I run more tests. The first test I ran was of a (very) deceased house spider - a terrible subject but I think it effectively demonstrates that the process is effective.