This is all a matter of how rigorous your definitions of observation and objectivity are. Some nihilists say that an observation is strictly personal, you can't say that someone else is seeing the same because you can never check if it's indeed the same. Therefore the only reality is your own. Well not a really practical and optimistic train of thought...
All sciences work within a certain paradigm with specific instruments and theories. Paradigms shift and new instruments are created. There is no true objectivity in science, you are always putting trust in manmade standards and instruments.
I had a large course of science philosophy in my psychology study that went into detail about objectivity, paradigms, observation etc. It was an eyeopener but it certainly made your head spin.