Follow up advice: if your DSLR doesn't have an input for an external mic, it's still worth using the in-camera mic to help synch whatever you record on an off-camera device. In fact, even if you can plug in a shotgun mic or similar, for anything other than vlogging, you'll usually get better results by recording your audio on a dedicated device (again, using the in-camera mic for synch). The sound guys can advise you better on exactly what combination of mics and recorders will suit if you tell us what kind of footage you're shooting.
I forgot that there's another (even cheaper!) technique for avoiding auto-focus noise: turn off autofocus!
My STM lens is arriving tomorrow! i'm childishly excited... and the cold shoe extender arrived today, i tried it and it diminishes the noise considerably, hopefully combined with the STM lens i'll be sorted... i dont know how to do manual exposure... but this is probably the time learn Thanks for the help...I forgot that there's another (even cheaper!) technique for avoiding auto-focus noise: turn off autofocus! Obviously this does depend on having someone who knows how to focus manually, and is available to do it while shooting (if you're tracking a moving target), but a lot of auto-focusing is just down to bad set-up, e.g. someone waves an arm across the camera's field of view, so the camera pointlessly tries to refocus on the new target.
I don't know if synching externally recorded audio in post-production is within the "rules" for sweded films, but it's actually gives you much more flexibility in who and what you record. Single or multiple mics can be hidden in various places on the set, close to the actors, to give you the clearest possible audio without needing a boom operator ... but what you save on the boom, you lose on the mixing later!