Flash

We had a flash night at photography club.  I NEVER use flash, so don't know what I'm doing.  

I bought this small flashgun years ago - and for some reason didn't sell it when I swapped from Canon to a Panasonic camera.  I learnt a bit last night - including adjusting the power on the pop-up flash and using this off camera.  One of our newer members asked whether I was thinking of selling the flash (he is a Canon user).  Obviously this flash doesn't work TTL on the lumix - so I'll really need to learn what I am doing to use it manually if I keep it.  So I guess the real question is probably whether I'm going to bother buying a replacement when I do sell it!