I'll try to get Colin's address for you to send the boys around.... beat him around the head with Diascopes until he see's stars or sense, what-ever comes sooner
Andy
You really should try out a range of binoculars.
You must ask yourself, in what conditions do I want to use my binoculars.
If you only want them for daylight use, then binoculars with a 20mm objective upwards would be sufficient.
If however you use binoculars in low light conditions, then you should look at binoculars with a larger objective (min 40mm).
Twilight factor and exit pupil are mathematical measurements, but the minimum factors for low light binoculars are: Twilight Factor 17. Geometric light gathering factor 16 (exit pupil of 4 has a geometric light gathering factor of 16). This however does not say anything about the prism system or quality of the lens.
There are also a number of other factors, but you should contact the manufacturers or specialised dealers for further assistance
There is only one binocular I would reccomend & that is Leica. Very robust & good eye relief. Not cheap I know but worth it if birding is your main hobby.
Don't worry MarK, he's a sad victim to the red spot/Steve Dudley syndrome.
I'll try to get Colin's address for you to send the boys around.... beat him around the head with Diascopes until he see's stars or sense, what-ever comes sooner
Andy