Had a nice gal ask me, the other day, if she could observe with an
astronomy binocular though her picture window, just like she does when watching birds at the birdfeeder with her
birding binocular.
Good question and I can answer yes, or at least, sometimes yes. When the temp is below zero, turning off the lights in the house and placing the
astronomy binocular up against the window is surely a temptation. Does it work, though? Again, sometimes. As long as the front lenses on the binocular are parallel to the window panes, you get minimum distortion and viewing is not too bad, assuming you have decent quality window glass. This would be much the same as when viewing through the window at a bird feeder. I've done this many times. The problem arises when we start to raise the binocular objectives away from that horizontal to the window and begin to view through the window, upwards at an angle. This produces noticeable distortion and the greater the angle away from that horizontal position, the greater the distortion. Since most objects we want to see in astronomy are going to require us to tilt the
binocular up, there is a limit to how well we can do from inside the comfort of our own home, though
the window. In practice, I have gotten up to about 45 degrees from ground level, but that's pushing it for some objects. For those objects high in the sky (where we really want them for the best view), we have to put on a coat and step outside. Brrr!Stay warm.