The framing method of a dual-lens reflex camera is equivalent to

The lens spacing is 65 mm, and two parallel photos can be taken at a time, which is equivalent to the scenery seen by two eyes. Use "binocular glasses" when looking at photos, so that the left eye can only see the photos on the left and the right eye can only see the photos on the right. In this way, the photos seen by two eyes are fused into a three-dimensional image. In this stereoscopic image, the objects in the foreground are very prominent, while the objects in the background are far away.

Dual-lens reflex camera was later replaced by single-lens reflex camera, mainly because SLR camera has the advantages of small parallax, small size, replaceable lens and convenient film. In traditional cameras, one is used for framing and the other is used for imaging.

However, lenses are generally not replaceable. If the two lenses are not replaced together, the parallax between the viewfinder and the imaging lens will be great. One of the characteristics of dual-lens camera imaging is that the image seen in the viewfinder lens is often different from the image recorded by the imaging lens on the film, and there is parallax. Also, framing is very troublesome and it is difficult to focus. You must start a magnifying glass to check your vision.

If used well, it is similar to SLR camera imaging. In addition, the double-reflex camera can alleviate the unnatural performance of the subject when shooting because the photographer bows his head when taking pictures.