Hi, I hope to ask not too stupid a question: I set out my newly arrived triplet 90mm refractor last night (65F-->15F) on the mount. Half an hour later, I found astigmatism in the star images (perpendicular ellipticals on both sides of the focus point)- could it have been due to the thermal stresses during such an extreme cool down? Of course, the clouds are in tonight so I can't investigate this. Thanks
Ivan
Ivan
