I'm shooting a Canon XS and it always seems that when on manual mode I can't get my aperature to go as low as I want. For instance when shooting manual the lowest I can often go is 5.0 but if I switch to the macro setting it will automatically drop to 4.0. Just a moment ago I was fooling with it trying to take one pic and the aperature on manual went down to 3.5 so I thought huh thats the apt I want for another pic so I took the tripod over (and didn't touch the settings) to the other object and took the shot. At some point the camera adjusted back to 5.0. Is there something I'm missing or some way to over ride this? Thanks ahead of time. I'm sure there's a simple explaination I'm missing.