On ebay all I have seen are the real big counter top densitometers. ON the BTZS video I bought davis uses a small one. When reading what people write here they talk about different channels but when I look at the descriptions of densitometers I don't see specific mention of different channels of light being measured or of included filters. I am so confused! Does anyone know who makes the little densitometer that davis uses in the BTZS video? DO all densitometers measure the different channels, and how important are they? I develope in pyrocat but will also be developing in non-staining developers in the near future.