Problems with flash unit on R5

[Hannes20]

Good evening!
May I ask for some help please.
I´ve switched from another brand to Canon and I do mostly nature and birds. My girl friend likes to get photographed (portrait/traveller shots).
I fetched an EoS R5 and lenses for Portrait shooting and travelling. I also got an third party flashlight Ex600RT from Yongnuo cheap from the dealer for starting.
I´ve just one problem: The pictures are all underexposed - very dark. I tried to use the flash manually, but it takes some shots to get the right exposure. This is not practicable in the field. I´m not a PRO, who knows how to deal with light. I were not using flashlights before.

Can I ask, if there is an good book, video or page, that deals with flashlights and Canon R5? I did not find something good in the internet.
Thank you!

 

[Roo]

It is something I have noticed recently with the R3 using the same type of Yongnuo. I had no issues at an event in September using 2 bodies with a flash on each but last weekend I had 2 events and they weren't playing nicely at all - under exposing when zoomed in and over exposing when zoomed out. They were both in ETTL with auto zoom working.

 

[danfaz]

I´ve just one problem: The pictures are all underexposed - very dark. I tried to use the flash manually, but it takes some shots to get the right exposure. This is not practicable in the field. I´m not a PRO, who knows how to deal with light. I were not using flashlights before.

Perhaps switch to ETTL and use flash exposure compensation.