I have a sony dslr camera thats about 10 years old, it doesn't take as good quality photos as newer cameras. I want to know if i should buy a lens or a new camera. What affects the quality more?
Without knowing which camera you've been using for 10 years, nor which lenses you already have, it would be very hard to give you useful advise about what to purchase, but I can tell you that I'm currently using some lenses I thought I might never use again (Zeiss lenses for CONTAX 35mm cameras—lenses 30+ years old, in most cases). I bought a Sony A7R after the A7Rii was already out and was able to use my old lenses again. I actually did buy a couple modern Sony/Zeiss lenses and was not satisfied with the price/quality ratio (build quality seemed poor compared to what I was used to). At the time I bought that, I had a Canon 650D and the upgrade to "full-frame" felt like a good move; better than buying a new lens. But it depends on your goals, budget, and (of course) on what you already have.