Always try what you have. That way you have a baseline of quality, and you can judge if it's good enough for you. I did a lot of scanning at 1x....but that was 7 years ago with a low res camera. The only reason to scan at higher magnification than whatever you have is if you need more resolution. There definitely is a law of diminishing returns. For your use, an old macro lens in the 50-75mm range would likely be the best bang for your buck.