Re: Leica spotting scope?
Gene is correct. The APO is short for apochromatic lens. The APO models have a different lense system than the non APO models. The Apochromatic lenses are made with flouride glass for improved image performance over the non APO models. On the newer models, there is an optically neutral front lense to protect the sensitive APO lense.
So what does this mean to the end user. The APO will cost more, and give better optical clarity, resolution....
I have both the APO and non APO models, and I can honestly say that my eyes cannot tell the difference between the two.
If it makes you feel better, spend the extra jing and get the APO..