Then you would want a focal reducer not a "focal lengthener"
though it would be handy for the moon for closeups of craters. Even then it is unlikely that you would do a better job than using a webcam.
The upside is you would have a larger field of view @ 21.7x32.5 arcmin (assuming your chip is 15.2mm x 22.7mm and has 7.4 micron pixels)