I have had no idea what this 4/5th stuff was. From the looks of the stuff on thast link above it not much more than a point and shoot with changeable lens? For me the best P&S I've used was one with a view finder. My presaent Nikon L24 doesn't have one. It does take nice photos but hard for me to frame them right. It doesn't have aperature pri, shutter pir and manual controls either. One thing I found with my Nikon is if I want the best photo I can get, put it away and get out a DSLR. I have seen some P&S cameras that do have a lot better controls on them. I gave my Cannon I5IS, think that is waht it is, to my grancson because it wouldn't fit in my bird vest. That was a mistake! My next P&S, soon as I can afford one will have the controls and fixed lens and some kind of belt pack I can carry it in. If I'm out hunting I don't want to give up the long zoom and carry extra lens with me.
