Observing and contrast

[nightvision]

I was trying to figure out some basic guidelines for maximising contrast especially when combatting LP and mist and or selecting the best scope and eyepiece combo for a particular object.

I Have noticed differences between my refractor and reflector they each seem to be better at some things. The small newt (114) can give a more contrasty view of the moon than the larger one (300) and my bins seem to deliver the crispest view of the moon.

Can reflectors and refractors deliver higher contrast if they are stopped down like a photograpic lens?

Is contrast only down to the quality of the optics or is there more that can be done? Could some aperture be traded for contrast or doesn't it work like that?

Tony.