الآلة ذات المسدد البصري .. طريقة عمل آلة التصوير .. كتاب التصوير الضوئي

The collimator .. How the camera works .. The book of photography

The collimator

The double telemeter

It allows for precise adjustment by aligning and juxtaposing two identical images separated. The images of the subject are seen through the eye of the telescope: they are superimposed when the lens adjustment ring is turned. The main image is the one seen through the optical collimator window and the second image comes from the telescope window by means of a circular prism system and a 45° mirror.

The collimator machines use a small optical device, often placed behind a rectangular window through which the subject can be seen and framed. The image is slightly larger than in nature, but there is a slight defect, which is that the field of light path
that the collimator sees is slightly different from the field that you see.

The lens, as our eyes do not see, each one separately, the same scene from the same angle. This defect in some collimator machines (especially old machines) is known as the parallax angle error. It is automatically corrected in most machines with a double telemeter, and the latter allows for a very precise calibration. The angle of the subject's divergence can also be corrected when forming the image by taking into account the symbols engraved on the glass of the telescope.

This principle of correction has been used in all machines of all sizes, from small machines to professional machines. For large machines, the optical telescope sometimes comes to complete the direct correction on opaque (frosted) glass.

Modern machines with a telescope:
The 35 mm machine is the most widespread among the well-made machines because it is light and easy to use. Many of these machines are equipped with a large set of lenses and additional parts. The development of engraving of clichés and the quality of films and lenses allows the use of the 24 x 36 mm size in journalism and publishing, this size is used by the majority of photojournalists. This machine is loaded with 126 film, which is also light, but less expensive and less perfect than others because it is intended for the largest number of people. It is easy to fill and easy to use. There are several models.

This machine is intended for professionals and this folding chamber uses single films or 120 and 220 strip films. It is equipped with a set of interchangeable lenses that contain all the main movements.

The monoblock machine, which is solid and solid, uses single films of 6 x 9 cm or films in a reel. This measurement is given by contacting readable images, which have interchangeable lenses but do not have any movement.

The invention of the 110 cassette machine was brought about by the improvement of films and the study of small-sized machines. Used for calibration are marks or symbols.

The very small machines are not new: they were very common in the 1880s. Today they have become more perfect and are equipped with a light meter (bosomer) and a flash, etc. They use 26 mm film and the speeds are often limited to five.