I met up with a retired commercial photographer the other day, and in the conver dation we talked about black & white film processing and he got all fired up abo ut a developer he used back in the 1960's called 777. I have never heard of it a nd neither did my local photo store that stocks a good amount of darkroom suppli es. This man claimed it gives the best shadow detail and won't overdevelop the h ighlights, he went on and on about this developer. Anybody know what he was talk ing about, and is this a packaged product or do you mix yourself???. Would this be a good developer for 4x5 black & white sheet film????