Quote: noquarter15: I own a K-7 with a 16-45mm lens along with MF 28mm and 50mm which obviously wouldn't work at a wedding.
I understand why you are reluctant to shoot with the 2 manual focus primes at the wedding. They are your friends, and will forgive a good deal, but you may miss too much with MF lenses. If you were only there to take shots for yourself, that would be different, but to shoot their wedding for them means you must be responsible. Towards that end, you need to have the equipment.
That said, it does not mean you must have the best equipment. The ISO performance of the K7 is good enough to allow you to use the 16-45 at a wedding--for sure--so long as you have some experience shooting @ higher ISOs. But I think you would really benefit from a faster zoom too--something like the Pentax 50-135 2.8 or either of the Sigma/Tamron 70-200 2.8s. You can rent these--possibly, if cost plays a decisive role here. Or you could rent/buy a fast prime. It really depends on your budget. Perhaps, if you offer your skills as a gift, they would pay rental fees to ensure they get quality files, ones which will print up LARGE and beautiful if the picture warrants it.
I'm not sure how this tent setup is, but I have shot under tents and the lighting is, to a large degree blocked more than I thought it would be. Especially if it is one of those tens which have side flaps in case of bad weather. You are better off having more speed than you think you need. Can you shoot under one of these tents, just to get an idea of exactly how much light there is, enough before the wedding so that you can make crucial decisions with respect to equipment?
Finally, do you own a flash?