I realize that this thread doesn't seem to belong here based upon its title. However, some of the most thoughtful posts occur in PRSI and I think this is the forum that will most likely generate an answer. Hopefully the mods will agree! This is a 'social' issue, IMO. I am working with a group in a developing nation that has very little in terms of modern instrumentation. The infectious agents we are interested in kill tens of thousands of people each year (globally). One device that they really need is a spectrophotometer (visible light) to evaluate density of E. coli cultures for transformation with recombinant plasmids. But they don't have one. So, in the absence of a dedicated spec, does anyone have an idea as to how a digital camera might be used for such a purpose? They have computers (both Macs and PCs) so the use of NIH Image (ImageJ) or some other software can be used. The assay must be quantitative in its assessment of optical density (or absorbance).