It's a tough situation. However, it comes with territory. You truly need a good contract to protect yourself from "accidents, equipment failures and such. You can down-load some example photographer contracts from the internet. I wrote mine from a book of contracts I obtained from my local library. It would be well worth your while to have one in place before you book another wedding. Good business insurance is also a necessary expenditure and it's really a minimal investment. I purchased a base business policy for around $230 a few years back when I was still shooting wedding. With that said, I do agree with Sandpiper that you should go out of your way to keep your customer happy. I think you should expect your customer to be at least reasonable though. Not all customers are going to be 100% happy. You do what you can and then move on from there. Next time your contract should clearly define your liability in these situation. Look at this as a learning experience. Good luck!

