Orion 3.6" Clear Aperture

I bought one of these and tried it out this weekend. I have a question about it someone here will probably know.
I diffraction ring tested it and the outside of focus rings are not nearly as well defined or as bright as on the inside of focus. Is this normal for this focal length scope?
Otherwise this scope really surprised me images are very nice. :S

Could be a number of things. Zones, turn-edge, or other
high-order aberrations in the glass can do it. Still it
is probably better than an achromat.

Also the atmosphere. Outside focus the scope is actually
focussed on middle and lower layers in the atmosphere.
So if there is turbulence it can contribute to differences
inside vs. outside. But if seeing was very steady at
best focus I would discount this option.

Hi Matt,

It could be that the warm air boundary layer in front of the mirror is to blame. When the boundary scrubbing fan in my 8" f7 is on and the scope is acclimated the in and out patterns are virtually identical. Turn the fan off and and things can get mushy.

Just a Thought,

Steve