The characteristics of tlr are

Tlr is characterized by two lenses, one directly above the other.

TLR, dual-lens reflex camera (TLR), also known as dual-lens viewfinder camera, is the same as SLR camera.

The product structure is as follows:

As the name implies, the biggest feature of TLR system is that it has two lenses, one directly above the other. The lower lens is responsible for transferring the image to the film, and the image from the upper lens is only used for framing and focusing. What people see is through the upper lens, but actually only the lower lens is used for shooting.

The light of the internal structure passes through the upper lens, and is reflected upwards to the horizontal frosted glass observation screen through the reflector with a 45-degree angle. The image on the ground glass is the same size as that on the film. The upper lens is connected with the lower lens through the transmission device, so that when one lens moves, the other lens will automatically move by the same amount.

As a result, when the upper lens is adjusted to form the clearest focus on the ground glass, the lower lens will also be automatically adjusted to form the clearest image on the film.

A typical TLR camera uses 120 or 220 rolls of film to produce a square negative with a side length of 6 cm. When using a TLR camera, you usually hold it to waist level and look down at the ground glass for framing.

The image seen on the ground glass is also 6 × 6 cm; And the up and down direction of the image is correct, but the left and right direction is opposite. Because the viewfinder image is formed after being reflected by the mirror once.

The structure of TLR system makes it exist as follows:

1. Because the viewfinder lens is separated from the photographic lens, TLR has parallax problems like paraxial cameras (that is, what you see is what you get). The disadvantages of this problem will be more obvious when shooting close-up objects. Therefore, some modern TLR cameras have built-in parallax automatic compensation devices in their framing systems.

2. Compared with optical viewfinder or rangefinder, the image on ground glass is not very bright. It is inconvenient to look down at the object in front of you in a waist-level way. Modern TLR cameras can overcome this shortcoming by adding an eye horizontal viewfinder accessory called Porro viewfinder.

3. As far as its inherent characteristics are concerned, the dual-lens system is huge, and it is necessary to replace both lenses at the same time when replacing lenses; This is really a problem for the current large aperture fast lens.

4. The interchangeability of lenses is limited. If you change the photographic lens, you must also change the viewfinder lens. Today's TLR cameras usually provide interchangeable dual-lens devices.