(faster shutter speed / less light). Aperture (or f-stop) refers to the size of the opening in the lens of the camera when a picture is taken. As you are focusing the camera, the lens is wide open with the largest aperture supported by your lens.
The harvest season typically falls between August & October in the Northern Hemisphere and February & April in the Southern Hemisphere. With various climate conditions, grape varieties, and wine styles the harvesting of grapes could happen in every month of the calendar year somewhere in the world. In the New World it is often referred to as the crush.
If you see birds on the vines, it is a good guide to ripeness. Once grapes have been picked, they will not ripen further. Therefore, wait until your crop is fully mature, then harvest by clipping off the bunches with scissors or a sharp knife. Pick them on a dry day because wet grapes do not keep as well.