Originally Posted by Delphinus
I know very, very little about optics but I have the opposite opinion probably is related with age (eye condition) and the final result in range finding but I for me expensive glass translates in more shift because it has more depth of field increasing the problem.
I never consider the temperature for so high variations but reading those postís itís a reality so what we wrote is related but is a distinctive issue.
Depth of field is a by product of the spec of the glass, more precisely focal length, than the quality of it. Problem is that scope magnification isn't really the same as we'd expect. It's a calculation of the focal length of the objective divided by the ocular focal length. Thus you can have two 50x scopes with different field of views and focal length. One reason why scopes appear to have a different view even though they say they are 40x or whatever.