Monitor ... relation of size to working distance?

[Rupert49]

I have heard somewhere that the diagonal size of a monitor screen should be approximately equal to the comfortable working distance from it. This would naturally preclude a huge screen in a small space, but that would be hard to view well anyway .. a bit like sitting in the front row at the cinema (why do people do that?!)

I am thinking that maybe a 19" or a 21" widescreen monitor will serve my photo editing intentions perfectly well (I've only ever used a 14" 4:3 laptop up to now). Does anyone have any sensible advice on monitor size, apart from (presumably) the price?

[AndyTake2]

Depends on the monitor.
Higher quality ones can be used close up.
I'm using a 30" NEC and the recommended distance is 60CM-ish, which is pretty much what I use.