Meade .33x gets down to F/3.3 .
I am not aware of any other options that could be used , which should not involve disassembling the corrector and buying $1000 worth of mechanical+optical parts .
The image below is shot with my home made reducer and my Meade 10 inch F/10 SCT .
The result is F/1.55 apparently (I might be off by a little, actual range based on transit time is 1.5 to 1.6 ) .
Is there anything like this available commercially ?
Please note that my reducer can NOT work with cameras that have a CCD any larger than 1/3" ( 6mm diagonal).