I have a 6" F/12 Superplanetary in pretty much mint condition. Problem is that the original 2" focuser uses a very small set screw to secure the diagonal in place and it is not adequate for use with a binoviewer. I am inclined to have a new AP focuser installed but am told that may require shortening, i.e. cutting, the tube as the new focuser is a lot longer. For many reasons I am hesitant to alter this wonderful old scope. Am I being too cautious? Are APs like this collectible and therefore should remain in "original" configuration?
I have a 6"F8 AP Triplet from the same era(1988-89). It's also in 'like new' condtion because the OTA was kept in my closet for 14 years waiting for a Alt-Az mount/tripod combo. Finally purchased the GR-2 DX mount after I was able to find a used Quick Set Hercules Tripod for a reasonable price. I love this combo because of the ease of set up. The 18" adjustable center column of the tripod works great. I agree that the focuser needs improvment. However, I would very hesitant if a focuser upgrade requires cutting of the orginal tube. The F12 is a rare model and I would want to keep it that way. I would differently the scope has heen modified before.
I think you are being too cautious. How will you feel when the binoviewer drops and breaks? A 6" f/12 scope is very cumbersome so some shortening is actually an additional improvement.
Yes, these scopes are collectable but I wouldn't count on it to be your sole source of retirement when you decide to sell it (lol). I don't think the 6" f/12 is as collectable as faster focal ratio AP scopes purely because of how cumbersome this OTA is. Upgrade with the newer AP focuser and continue to enjoy the telescope.
If you are concerned about investments making a profit, pay close attention to your stocks and stock funds (especially the fees).
If your going to install a new Astro-Physics focuser I would think that would increase the value of the that scope. The older focuser if I'm thinking about the right F12 model that you have had a very basic 2 inch focuser. A new 2.7 inch model would be a definate improvement over the older design. I would go ahead and do it. If your nervous about modifying you own tube maybe Astro-Physics well do it for you.