mirror lens

So I recently bought an old lens for quite cheap at a thrift store (the specs on the sides say "Spiratone 1:5.6 f=300mm Mirror Lens No.8300968 ø72 Minitel-S Plura-Coat"), and it appears to be built for SLR cameras rather than my Canon Rebel. I've done some research and it appears that a t-ring...

Hi guys, I just found one of theses beauties, but sadly it is missing the 35.5mm rear filter required for it to focus properly. Therefore, I am looking for anyone who might have a broken 250mm minolta rokkor lens or had gotten the optional filter set and would be willing to let one of thoses...