Can anyone explain how to calibrate the viewfinder without a reference monitor please?

Hi John and welcome to DVinfo. There really isn't a lot of "calibration" you can do. What sort of screen are you using when you edit? Have you attempted to calibrate it in any way? For starters, I'd suggest trying that - see the following, which will get you somewhere in the ballpark:

http://www.videouniversity.com/tvbars2.htm

After you've done that, take your camera and try to match it to you monitor as closely as you can. It won't be perfect but it will give you some idea.

Thanks for that. I am using an LG Flatron LCD screen attched to my PC.