Is there any way to put a microphone on a Canon sx50 hs camera? Can I use a 2.5 to 3.5mm converter?

Using an EXT Mic will depend on your OS and what type of interfacing it has for a MIC /LINE / AUX input...I use a PA brain mic channel into an RCA input stereo breakout box (from the 90's..LOL) to interface the computer BUT, if your using windows , you should have a MIC IN, and most interfacing is 3.5mm plug, into your sound card....Then, when you go to configure video and audio devices in your video recording software, just have your computers sound card handle the audio instead of the camera. Usually you'll have an LED indicator at that stage to show your peak audio levels so you can see how hot ya want it...OR, if ya wanna go digital mic IN using USB, you can use a USB Mic and just configure that device to handle the audio....Heck , Im still using good ole Movie Maker from WIN XP and it allows all the audio/video device configuring so I KNOW using anything newer will likely have 2-3-4 different ways of doing audio and video synced...You can take a regular pro quality vocal mic thats LOW Z and put a HIGH Z transformer( called a pig tail in the 70s)on it (to adapt it down to 1/4" ) THEN get a female 1/4" to male 1/8" (3.5mm) and that will allow it to go straight into your soundcard and ya wont have to buy an audio interface. BUT, in all honesty, if your gonna be doing videos and ya want good sound, it would be worth the $$$ to get a good small audio interface (analog mics XLR , 1/4in etc. to a USB IN ) and that way you can PREAMP and PRE EQ your sound before going into your software...I know , prolly more than ya wanted to know but ...???...LOL .. hope this gives ya some ideas.