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Short vs. Regular SCT Adapter

Started by astroboy314, 12/19/2002 10:28AM
Posted 12/19/2002 10:28AM Opening Post
Hi all, I am looking at moving into the 2" diagonal world and am looking at the available TeleVue adaptors to fit a 2" diagonal into my SCT.

What is the difference between the short and regular version besides the length. I have an equatorial mount so clearing the fork mount isn't an issue. Is the image quality different? Is it easier to bring some ep's to focus with the short version? Anyone know the actual measurement and weight differences?

Does TeleVue even sell their regular anymore? The few sites I've looked at only list the short adapter.

Thanks for any help you can offer.

Dave

Posted 12/19/2002 09:25PM #1
David,
I don't know anything about the Televue adapters. But the longer one is, the greater the magnification, as adjusting the mirror to achieve focus, alters the focal length. S&T had an article on this a while back. And I recollect the point being made somewhere that manufacturers try to optimize their SCTs for a certain point, at roughly where a camera's film plane or 1.25" diagonal goes. But quite frankly, I've never noticed the difference.

It's interesting that you have an equatorial. I have one to, but there aren't many around nowadays. I far prefer picking up the entire unit and carrying it outside in one go, than having to muck around with the multiple pieces I've seen Fork mount owners having to do. Mine is almost a handy grab and go telescope.
Renato
Posted 12/20/2002 05:39AM #2
Hi David. I have just gone through the same situation. It is my understanding, and I could be wrong, that the TV short SCT adapter is also designed for the Tele Vue diagonal with the short snout as to match the undercut on the diagonal to the compression ring on the adapter. Since I have a regular 2" TV Everbright diagonal, I bought a used
regular style TV SCT adapter off Astromart. Pat G