One of the reasons (Harvey's)777, (it had other names like "panthermic") is so hard to find is that it's principal developing agent is p-Phenylenediamine (1,4-Diaminobenzene), which Ed B describes as being basically obsolite. I do know how this formula works and it should work best in silver rich films. It can work magic in the highlights and the deep shadows that I have not seen exibited with high repeatability in any other B&W developer. It was the workhorse of the NY studio croud back when B&W was in demand and the secret of the photojournalists who did the impossible. 777 certainly is a developer which had a look all it's own when used to its best.(posted 8332 days ago)777 seems to work best at 75F and above, and is best used in large quanities (big tanks). It changes a little after the first few rolls and a new batch should be ripened with a few unimportant rolls and it will then be stable for years. It really lasts well, even though it visually is not confidence inspiring in looks. Murky is normal. It is hard to mix, and the initial mixing is critical. Agitation is quite important. Do it the same every time.