So what do you suppose is the difference between the older AP 130 F/6 and the newer AP 130 Gran Turismo?
The difference in the OTA with all the bells and whistles of the GT is obvious. The older 130 F/6 is lighter by about 2 pounds I was told. Anything else?
Well I decided to go to the top and this is the answer I got:
"No difference optically. Both are oil spaced lenses. The original design (130F6) used glass that is no longer available in high quality levels so we were forced to change the design to another type. The glass we use must have no internal defects like striae or index variation. This glass was discontinued by the large glass makers, Ohara and Schott, and is now only available from a Chinese company. We tested this Chinese glass and it was not suitable due to high reject rate of over 40%. The newer design requires more extensive hand figuring (the old design was all-spherical), but I have a method for figuring that produces great results, so that's the way we are presently making them - newest glass of high quality and hand figuring."
Hand figuring by the man himself. Now that is pretty cool.