Quote:
Originally Posted by Merlin66
The "original" Meade/ Celestron X0.63 reducer was specifically designed for a distance between the rear rubber shoulder to the film plane of 110mm. (The doublet has a focal length of 240mm)
There is no restriction on the positioning of the reducer in the optical axis, generally it is mounted on the rear SCT thread of the mirror cell.
Some years ago there was a "dud" batch of these reducers ( with a far shorter focal length - they were similar to the x0.33 reducer focal length) and this gave rise to many discussion on many forums.
Two years ago there was talk that the reducer had indeed been changed to a shorter focal length. I have never seen one of these.
Interestingly, no one has commented on the Celestron version...this still seems to be the same as the original and still needs the 110mm spacing.
(If someone has a shorter focal length Meade x0.63 reducer I'd love to hear from them)
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Ken
I have just bought a new one to go on my new C11 (
). I set it up last night with the LISA attached and it seems to work very well. No idea about the image quality as I'm not really interested in the quality of the off axis stars on the slit. It certainly produced a nice spectra of R71. I will take it off again and measure the fl.
The LISA has a focal distance of 41mm to the T thread. The adaptor I have is about 10mm long so about 51mm in total. It probably doesn't matter for spectroscopy.
Cheers
Terry
