Hello, I am new to photography and want to take a next step inside. I am currently interested in the Canon Elan 7 body with a 28-105mm lens. My question is, since I am on a tight budget, I am considering between 2 types. The f/4-5.6 and the f/3.5-4.5 models. How much difference is there really to this technical detail? Since they are around 100$ apart I would like to know if it is worth the "investment". Also, if you folks here have another suggestion to propose me, maybe another camera brand & model, I would be glad to hear about it. Thank-you.