I have a chance to score a Canon A1 with good lenses, speedlight, filters...blah blah...for a good price. It's a camera from the 1970's, manual focus et al. I want to be able to use this for concert photography but it's average-weighted metering only. I want to know if there are tips/tricks for faking/compensating for lack of spot metering. Any good sites where I could post questions?