I practice photography only as a hobby. Perhaps a pro or semi-pro photographer can come along and give you a better answer. 35mm refers to the film negative size. Film negatives use to vary quite a bit but then 35mm became the standard. The larger th...
Don't understand your question, the retina is essential to sight, if you haven't lost the use of your retina, there aren't too many other causes of blindness-the guy above who says cataracts has probably hit upon the only other cause, except the rare...
Generally speaking, when looking through the viewfinder, there will be a yellow square or diamond superimposed on the main viewfinder image. When this yellow box is coincident(lines up with) the main viewfinder image, the camera is in focus. This ass...