[JohnBax]

Be sure t watch Northrup's second and more recent video on it, explains further and back tracks a little on his earlier video.

Thanks Bob,
I have watched Tony's films which are up to 4 now, the latest being a rant by a guy called Joe who was thinking on similar lines to me. Having watched this film I understand better what Tony is saying and agree that some manufacturer's do pick and choose how they describe their cameras and it is misleading such as Panasonic stating the camera has a 25-600 lens at f/2.8 which is clearly impossible. I did read somewhere that the aperture is measured by the diameter at the focal plane not the actual opening in the lens which may affect my view if this is the case and to be fair to Tony {possible sign of back pedalling!!} when he takes the photos it does seem correct but he has not tried using different lenses on the same camera i.e. a full frame lens and a cropped lens on an APS C camera. Anyway thanks for taking the time to get involved with my question.

regards

John