Thanks for the replies. I called my eye Doc this morning and explained my situtation, he can provide "Occupation bi-focals" these are used by mechanics, electricians etc so when you look up you can have the close in vision exactly the same as when you look down. The problem is that when you are looking through the bifocal lens your long range vision is poor, depending on the individual. Target shooters can have glasses made up to suit specific circumstances targets and range distance, that will not work for for me in this situation, as I must have versatility.

When my .470 arrives I have arranged to take it to my Doc and see it it is possible to have new glasses for "Occupational bi-focals" to be made up. It will be interesting to see if a compromise with new glasses will work. In reality I would rather keep my sharp long range vision and a overly blurred rear sight and trust to good rifle fit and instinctive shooting, based on lots of practice. (Ten rd a week from when the rifle arrives until Spring 08.

The target "Mr. Buffalo", target range, lightning, movement and time to take the shot may make my concern unfounded.

Rear sight design combined with the appropriate front bead will also have a bearing on the practical results. I am now thinking that the old English doubles were fitted with platinum line on the rear sight and an ivory bead for very good reason!