stop air leak when disconnecting inflator from presta valve Presta novice question. When removing the adaptor and quickly screwing the inside core down, air escapes. I've changed from a short Zefal pump to using a compressor. The tire says 50-60 PSI, but by the time it is disconnected I lose a lot of air. Do I go with the tire PSI or presta recs which are like 80-100? Thanks!
In my experience there is always some air loss when you remove the pump from a Presta valve, but that air is lost from the pump side of the valve.

It's easier to see with a floor pump, since there's the hose to hold air. In a floor pump there's a check valve is at the pump end of that hose, and that will hold the air in the hose at high pressure even after you let go of the pump handle. That high pressure air escapes when you release the valve.

With a handheld pump there should be much less air released when you pull it off, because there's probably no check valve - the path from the pump chamber to the tyre is so short it's not necessary. Because it's so short there's not a lot of volume to hold high pressure air. Even if you release the pump from the valve while holding the pump handle in, you'll hear a little "phut" as the air escapes rather than the long "pssshhh" from a floor pump. But usually you let go of the handle, it gets pushed out a little until there's not enough air pressure to push it further, and when you pop the handheld pump off the valve you don't hear anything.