I'm using Sony A7R II with 28mm lens and I'm curious why my focal length change slightly? it's a prime lens and manufacturer spec says it's 28mm and the aero-triangulation optimized the focal length in the range of 27.13mm - 27.20mm for different photogroups. Should it not always be 28mm? if my focal length is incorrect, does that error propagate to the accuracy of the result?
Thank you
Chan