Angel Gomez said:
In the case of oil spaced designs the oil hides the sleeks and the lens appears clear. In air spaced designs without the benefit of the oil to hide them the sleeks can easily be seen in reflection only.
The oil does more than "hide" the sleeks, it eliminates the scattered light. If the sleeks in an air-spaced lens are visible on reflection, then they will also scatter transmitted light. You can't have one without the other.
Does it matter? We can split hairs all day about the importance of scattered light in amateur optics.
Jim McSheehy
