Is it doable for somebody with shaky hands (me) to shoot macro handheld? I know I should get a tripod, but I don't have one yet. I was trying to shoot some stuff using a 55mm and when it goes to 1:1, the shaking is noticeable in the viewfinder. I used a shutter speed of 1/500, will that do? What might be the lowest shutter speed to use without necessary blur?