16 THE BRITISH NATURE BOOK 



Now for the lens. The telescope object lens is of too long a focus to b used 

 as it stands, and you must use with it a spectacle lens to shorten the focus. 



Find, among your chipped lenses, one of about x 2.50; this goes at the 

 bottom of your pill-box (A, in Fig. 18). Next comes a circle of black card- 

 board (B), with a small hole in the centre not more than J inch in diameter ; 

 put that upon the spectacle lens ; and then add your telescope object lens, 

 with the curved side down (the flat surface being nearest the box lid). You 

 will find out how to fix these in position so that you can remove them readily. 



All is now complete. But note that the inside of the camera body should 

 be blacked all over ; and if any light should show through the corners or joints, 

 this must be stopped out. The outside of the camera can be covered with 

 American cloth, painted or varnished according to taste. 



A focusing screen is required at the back ; and if you have a metal dark 

 slide of the ordinary pattern, the following is a simple way of making a ground- 

 glass screen : First get a piece of cardboard stout postcard, about T V inch 

 and cut it to the same size as your dark slide, so that it will slide in and out of the 

 grooves at the back of the camera. Obtain a piece of ground glass of the same 

 size. Out of the middle of your cardboard cut a rectangle 4 by 3 inches, and 

 glue the frame that is left upon the ground side of your glass. If you like to 

 make a neat job of it when dry, bind the edges with strips of black lining. 



Your camera, if made according to these instructions, will now have a 

 " compound " lens of about 6 inches focal length, and the focusing arrangement 

 will enable you to take photographs of objects as near as two and a half or three 

 feet a very convenient distance for such subjects as birds' nests or flowers. 



If you would wish to photograph smaller objects, to appear a good size on 

 the plate, you must take out your spectacle lens and put in its place a stronger 

 one (X4-75) ; this, combined with your telescope object lens, will enable you 

 to photograph objects such as beetles and moths from a few inches away. 



It is necessary to have a cardboard disc for such purposes, with a smaller 

 hole than J inch. And I should advise your making one with an aperture of 

 |, and one with ^ of an inch. 



As already stated, some of the photographs in this book were taken with 

 this camera. 



When you are able to afford a more expensive lens and shutter, all that 

 will be needed is to make a new panel upon which to mount your purchase. 



The camera, thus made, focuses at the back. Practically the majority 

 of modern cameras focus by drawing out the front ; but, after many years of 

 Nature photography, I have no hesitation in saying that for taking photographs 

 of small objects (and these form the greater part of the living things around us) 

 it is far better to have a camera focusing from the rear. In photographing 

 butterflies, beetles, small flowers, etc., it is necessary to have the camera 

 within a very few inches of the object, and in this case it is very difficult to focus 

 from the front of the camera ; but the difficulty vanishes entirely if there is 

 a means of focusing from the back. 



