First, I am a wildlife ecologist who does some very amateurish photography on the side. I would like to start using digital photography techniques to collect field data.
The Problem: I need to take pictures of a certain colored object outside. Let's call it a red ball or a red cylinder. It will be partly obscured by plants in most cases and photos will be taken during different times of the day. I need to be able to control for the variation in shading and lighting that may occur so that the reflectance of the object returns the same value in each photo.
Options: Can I use a sun-shade, flash, and/or restrict my photo times to certain parts of the day to help with this? is this as simple as metering off a standard 18% gray card every few photos (or say every 30 minutes)? Could this be accomplished in post-photo editing software? It doesn't have to be perfect. It just needs to be repeatable.
Thanks, Matt B.