Binoculars and Spectacles?

[AndyTee (Andy)]

Not sure if this is a silly question, but after years of naked-eye observing I recently acquired a pair of astro binoculars (Orion 20x80s). I wear two different pairs of prescription spectacles, reading and driving. I have tried the binoculars all three ways - no specs, reading specs and driving specs. The binoculars appear to focus in all three cases, but is there a preferred option for viewing?

Related question - where is the eye actually focussed? At 'infinity' or on an element within the binocular itself?

[dannat (Daniel)]

You only need to wear your glasses if they correct for astigmatism, if you're long or short sighted you can use the binos focuses to correct for it
But if your long sight is bad, if might be easier if you wear glasses to pick out the fainter naked eye stars

[GraemeT (Graeme)]

Daniel's right.
To tell if you have an astigmatic correction in your specs, hold your readers at arms length while wearing your distance specs. Look through each lens of your readers in turn at a straight line or preferably a cross. This could be a door jamb or window frame or a high contrast thick texta cross on a piece of A4 paper stuck on the wall. Then rotate the lens in the plane of the wall or door and watch the image of the line or cross. If it appears to twist or distort in a scissor fashion, there is a cylindrical (astigmatic) component in the lens.
Small amounts of movement are usually of little consequence, but big image swings mean that you will probably get a better image wearing your glasses.
If you're still in doubt, just ask your optometrist if you have significant astigmatism. (S)he can give you that information just looking at your prescription or your specs without needing to charge you for a consultation.