The F-stop settings are what set the size of the camera's aperture, the hole that opens up to expose the ccd (i believe that's what it is in a digi cam, I use film, so normally I would say to expose the film). F-stops can go from 22 to 4 and sometimes lower. Basically, the smaller the F-stop number, the bigger the size of the hole of the aperture. Each step you take down from F-Stop 22 will let in double the amount of light that the previous f-stop let in. Also, the F-stop is also mainly used to control the Depth of Field in an image, ie: the range of acceptable focus. The higher the number, the greater the depth of field, thus, the majority of the picture will be in good focus if you set your focus properly, aside from very close up objects. The lower the number, the shallower the depth of field. If you set the aperture to it's largest setting, the range of focus is extremely limited, so you wanna make sure when focusing through the viewfinder (or lens on an SLR) that your focus is pinpoint accurate. Neither high or shallow depth of field is good or bad, it dep4ends on the type of image you want to capture. Also, the lower the number of the aperture, the less time that will be needed to expose (cuz the hole is bigger, allowing in more light). As for ASA, that stands for the "film speed," the speed at which film reacts to light. As a predominantly 35mm film user, I really can't help you out with what it does for a digital camera. Basically though, your image quality will "degrade" or become "granier" the higher the film speed you use, but the image will be exposed much fast at the same time. Last I read, most digi cams tend to start sucking once you go past ASA 400, but I wouldn't know for sure. It's a field of playing trade-offs really. hope that helps.