Goerz panorama sight

 

 

 

 

 

The Goerz panorama sight (Panoramafernrohr) consisted of a short telescope bent at right angles and surmounted by a moveable head. The head was fixed on a horizontal graduated table and was capable of being turned in any direction by a tangent screw. The object-glass Nr. 49 was in the vertical tube and the light was reflected to the eye by two prisms or mirrors inclined at 45°, one, Nr. 79, in the moveable head and one, Nr. 82, in the angle of the telescope.

These two prisms would not suffice to give an erect image, as if the head were turned round the image would appear more and more inclined, until at 180° it would appear inverted. Therefore a rectifying prism, Nr. 80, was introduced. Its was connected by gearing with the moveable head so as to revolve with it, but at only half the rate of angular revolution. This gave an erect image in whatever direction the head was turned. The magnifying power was 4, the field 10°.

The Goerz panorama sight was equipped with a goniometer placed above the sight on the same frame, and with a collimateur Nr. 92, placed sideways, outside the tube, arranged so that the line of sight of the telescope and of the collimateur were parallel. It was protected by two glasses that prevent to get dusty. The rear part, turned toward the observer, was convex, while the fore part had a cross without the upper arm. Looking across the collimateur, the cross appeared in infinitely. The longitudinal cutting of the glass cylinder enabled to see directly the target, and to point in direction and in elevation by means of the collimateur cross.

The goniometer was an aiming circle divided in 6400 parts, so that the case of the goniometer had 64, and the drum 100 subdivisions. A full turn of the drum corresponded to one subdivision of the case. The calculation of the extension of the the target and of the correction of the fire were made in millièmes, with a margin for error of only 0.02/1000, which had no influence on the fire for all practical purposes.

 

In firing the panorama sight was firmly fixed to the sight-bar, since the accuracy of the aiming resulted mainly from it. In depots, parks and on the march it was put in a canvas case, and placed on the box of the carriage, to be on hand if necessary. It was be fixed to the sight-bar just after its use, during the firing preparation, but, if it was already mounted during a march, it was necessary to check accurately that it was attached properly, to wipe the ocular and the protective glass, and to set the drums on zero. A spare telescope was usually carried on the limber or on the ammunition wagon.

 

At the beginning of World War I the Goerz panorama sight had been almost universally adopted, even if it was quite expensive, since the optical portion alone cost 630 leva in 1910. It was introduced in 1903, and was continuously improved and updated year after year. By 1906 the firm Krupp equipped all its trial field and position guns with it, concurring greatly in its diffusion. As for the Balkan countries, it was adopted by Romania in 1904, by 1908 by Greece, in 1910 by Turkey, and in 1911 by Serbia.

It could be easily adjusted to every kind of artillery piece, irrespective of the kind of sighting device that it had. It could be employed to aim with guns fitted for an independent or a dependent line of sight, since it  could be mounted either on an arc, a rocking bar, or a pedestal. It served both as an ordinary telescopic sight and as a dial sight for laying at an auxiliary mark.

It had the advantage of enabling the layer to see over the top of the gun-shield without exposing himself, and of giving a high line of sight, enabling the gun to be kept well back under cover. As all prismatic optical appliances, it was put out of action by dust on the faces of the prisms. Therefore the openings that allowed the passage of the light rays to the reflective prism were fully closed by glasses or lenses, and the rotating gears, like the reflector or the collimateur, were separated from the rooms containing the two prisms and the objective.

 

SOURCES :

-     Société anonyme C.P. GOERZ: La lunette panoramique. Berlin – Paris 1907;

-     BETHELL. Henry Arthur : Modern Guns and Gunnery, 1910. A Practical Manual for Officers of the Horse, Field and Mountain Artillery. Woolwich : F.J. Cattermole 1910, pp. 89-90.

 

 

 

Technical characteristics

 

Weight of the telescope :

1.35 kg

Magnifying power :

4x

Actual field of view :

10°

Fictive field of view :

40°

Entrance pupil :

16 mm

Exit pupil :

4 mm

Focal length of the objective :

80 mm

Focal length of the eyepiece :

20 mm

Vertical distance between the axis of the eyepiece and the axis of the reflective prism :

180 mm

Deviation of the reflective prism :

± 300‰

Scale of the goniometer :

6400