Surely you mean 611, 612, 613 or 614?
Kowa's numbering indicates that the first two above, ending in 1 and 2, are non-flourite lenses, and the scopes ending in 3 and 4 are flourite or ED glass.
If the number ends in an even number it is straight through, ending in an odd number indicates that the scope has an angled eyepiece.
I think this is true of all Kowa's scope series including 500, 600, 660, 770, 800, 880 etc. There are 4 models in almost all of these (except the 500), comprising 2 straight and 2 angled (one of each is flourite or ED, and the others are 'normal' optical glass).
The first 2 digits indicate the objective size in mm of all the scopes in each series (the exception being the 800 series which have 82mm lenses). This at least applies to the current range I think. The older 611, 612 etc range has been replaced a few years ago by the 601, 602 etc. which all have 60mm objective lenses. Therefore a '1' in the middle indicates an older model. Very complicated I know! but there is some method to their madness, in a range of scopes much larger than that offered by most makers.
Expect to pay considerably more for any scope ending in 3 or 4.
Steve
