I've been doing night time observing and imaging for a few years. A few months ago I mentioned some interest in observing and imaging the sun. Yesterday a friend loaned me his Coronado PST. It was given to him a long time ago and he never had the original eyepiece. He used the PST with a DMK camera for imaging and never really did much observing.
He gave me the PST with a 12.5mm no-name/markings eyepiece in the PST. I tried to get the scope to focus a few times but I was never able to get the scope to focus. This morning I tried again. I could get the scope to focus by sliding the eyepiece completely out of the holder (a 1-1/4" extension was way to far). After that I went and grabbed a 25mm Meade (Kellner??) eyepiece. I had to slide it out of the holder about 1/4"-3/8" to get this eyepiece to focus with the scope.
Do the PST's have a long backfocus (sorry, nomenclature isn't my strong point) and need eyepieces with long barrels, or is there something wrong with the scope, or am I just doing something dumb?