Sight but not salvation: telescopic sights in 1951

One of the limitations of the human eye is the inability to keep in focus at one time the backsight, the foresight and the target, and the telescopic sight is an instrument to overcome this disadvantage. After the age of 40, the eye loses some flexibility of focusing power and the fitting of a riflescope will often rejuvenate the rifle shooting of those no longer youthful.

It cannot be too strongly stressed, however, that the telescopic sight is only a sight and the fitting of one will not convert a poor rifle into a good one. The beginner is usually wildly enthusiastic after his first glance through a scope, and the size and clearness of the target make him wonder how he can ever again miss. But his first shot soon disillusions him and shows only too clearly the wobble that is not so apparent when you are using open sights.

How a telescopic sight works

A telescopic sight is a simple telescope with an extra lens to bring the image the right way up, fitted with cross-wires that, by optical magic, appear to coincide with the target. The eye is centred automatically and focusing is similarly taken care of by optical means. When properly adjusted for range, the bullet should strike the point covered by the cross-wires.

The power of a telescope is a function of its length and it is possible to obtain a scope that magnifies 20 times. But one of this power would be about the same length as a normal rifle barrel. However, for ordinary sporting use there is no advantage in going beyond 4x since very high magnification will enormously increase the apparent wobble as well as reducing the field of view.

Light-gathering power beats magnification

Much more important than magnification is the light-gathering power, which is governed by the diameter of the object glass and the quality of the lens.

A good-quality scope will give a fine, clear image, even at dusk, while a poor one will show a dull one coloured like a rainbow. The new “bloomed” lenses will again increase the light’s power. And in addition, enable one to shoot into a bright sunset, without dazzle.

If you’re buying a scope for sporting use on small game and rabbits, choose a short, fat one and 3x or 4x, and avoid any that give rainbow effects. Since telescopic sights are often used on high-power rifles, where the eye might be damaged by recoil, some ‘eye relief’ is usual. This is the distance from eye to eyepiece for maximum efficiency, usually 1½in, and riflemen who like to be close up to the backsight can fit a soft rubber cup.

German glass and the ex-army bargains

Before World War II, the best scopes available were of German manufacture and they still command high prices, but the wartime demands of the services made our optical craft the equal of any. A modern British scope will adorn and enhance the most expensive rifle. Most American scopes are mass produced and are best left attached to the firearms for which they were designed.

There are many excellent German and British ex-army scopes now on sale at what appear to be low prices, but buyers are warned that the fitting to a rifle may cost several times the price asked for the scope. A really good telescopic sight will cost £25 fitted today, and such an instrument deserves a first-class rifle.

What a good scope makes possible

A good telescopic sight will enable a good Shot with a decent .22 rifle to kill almost every sitting rabbit up to 75 yards. Kills can be made at 100 yards and over, but they should only be attempted when the exact range is known, and on windless days.

Educated vermin that seem to know the killing range of a shotgun to a yard can be outwitted and the telescope is invaluable for spotting those half-concealed rabbits that are often overlooked with the unaided eye.

This article was first published in the 25 August 1951 issue of Shooting Times.