lens adapter

Hey guys! So I have a Canon EOS 1100D(Rebel T3) and was looking to mount a Helios 44-2 onto there - which outside of an adapter I can do, no problems. But as my 1100D(Rebel T3) is a crop sensor I wanted to get an focal reducer to make the most of the lens but I am struggling to find one - I'm...

TLDR - I own a Polaroid SX-70 and I want to be able to attach lenses to it, how would I do that? Brief info on the camera: A quick expert from a wiki page - “The SX-70 has a folding body design, a 4-element 116mm f/8 glass lens, and an automatic exposure system. The camera allows manual focus...

I have an EOS R with the RF mount on the body and was wondering if I could use Canons 1.4x or 2x extender to place in-between the lens and the EF adapter?? has anybody done this and does it work with autofocus? if not does it still work with manual focusing? I want to use Canons mki 100-400mm...