Hi Patrick and colleagues,
I am using multiSPEC 4c. It is, of course, equipped with a radiometric target created by the French company AIRINOV. It took me forever to get the reflectance/albedo values. I simply emailed the company and wrote the manufacture number of the target. Every manufacturer must know the reflectance values of their targets produces. Moreover, the values may vary (99% of the cases).
Moreover, our target has the reflectance values only for our camera’s 4 bands. I would suggest buying a multispectral camera with a target not only the target.
If you have more question regarding this topic, contact me I’m not a pro but doing a research in this field.