أنواع الكاميرات .. الكاميرا العاكسة ذات العدستين .. كتاب فن التصوير الفوتوغرافي

Types of cameras.. the two-lens reflex camera..

3- Twin Lens Reflex Cameras

Figure (9) shows a typical two-lens camera. And this camera is two machines in one box, where the two lenses are compatible and have the same focal length (focal length) so that they give two images of the same size and they are, i.e. the two lenses are installed in a way that if focusing is done for one, the focus is achieved automatically for the fixed lens, and this machine works as follows :

The image passing through the upper lens is reflected upwards on the Viewing Screen. As for the image passing through the lower lens, it falls on the film. Since the two lenses are optically separated, the reflective mirror is installed in a way that makes the image permanently visible during the process of exposing the film to the image projected from the second lens.
Here we must remember that with the two separate lenses there is a parallax. This type of camera does not solve this problem as a single-lens reflex camera does, but most dual-lens reflex cameras are equipped with a means that corrects the error resulting from the difference in the image.

In general, in reflex cameras with two lenses, films measuring 1/4 x 2 1/4 inch are used in a roll containing (12) images.
In general, the lenses of this type of camera cannot be exchanged, but there are some known types, where the lenses can be exchanged (photo 10).