b BRITISH BUTTERFLIES. 



CHAPTER IV. 



PHOTOGRAPHING BUTTERFLY EGGS. 1 '' 



My first attempts at photographing ova were made with an ordinary 

 ^--plate stand camera, focussing from the back, attached to a student's 

 microscope, and with this I was able to obtain results which surprised 

 me, but was handicapped by the short extension obtainable with the 

 camera (about 15in.), as this necessitated using the eyepiece of the 

 microscope to bring the image to a focus at a point nearer the objec- 

 tive than would otherwise be necessary. This caused some loss in 

 definition, and I also had considerable difficulty in getting an objective 

 of long enough focus to cover the whole of a small batch of ova and at 

 the same time admit of the object being focussed with the eyepiece I 

 possessed. Having obtained a 3in. objective which filled these neces- 

 sary requirements, the next step was to construct a base board on 

 which to fix the camera and microscope in proper alignment. For 

 this purpose I used a smooth deal board about 3ft. long, 6in. wide, 

 and lin. thick, and ruled a straight line down the centre from end to 

 end as a guide to obtaining a proper alignment of the completed 

 apparatus. On placing the camera and microscope upon it, with the 

 body tube of the latter lowered to a horizontal position, I found that 

 the line of projection was considerably below the lens aperture in the 

 camera front, so the next step was to construct a block for the micro- 

 scope to stand upon, which would raise it sufficiently to bring the 

 eyepiece exactly in the centre of the lens aperture, and permit of an 

 imaginary line being drawn horizontally from the centre of the 

 objective to the centre of the focussing screen of the camera, and 

 pass centrally through the intervening portions of the microscope 

 body and the camera. This block I screwed down firmly in the 

 required position, and fixed small wooden stops at the sides and ends 

 to prevent the microscope from slipping when placed on it. 



I then drilled a hole for the camera screw in the centre of the base 

 board, in such a position that, when the camera was screwed down to 

 it, the lens front just touched the eyepiece of the microscope, when the 

 latter was racked out to its fullest extent. It was now necessary to 

 devise some means of connecting the microscope with the camera in 

 such a way as to exclude all light except that passing through the 

 former, and yet to admit of focussing being done as usual. To do 

 this I obtained from an instrument maker a short brass tube about 

 lin. in length, with a screw thread cut on one end to fit the lens 

 flange of the camera. This I screwed in, in place of a lens, and then 

 made a sleeve of black velvet to slip over it, long enough to be drawn 

 over the microscope body tube, and held in place at either end with an 

 elastic band. This answered admirably, and I found that after 

 focussing an object on the stage of the microscope and then con- 

 necting the microscope with the camera, I was able to get a sharp 

 image on the ground glass of the 1 Latter with the extension at my 

 disposal, and to reduce or enlarge this by altering the amount of 

 camera extension, and then to refocus with the microscope by stretching 



* This chapter is by Mr. A. E. Tonge, who is doing the photographs by which 

 this book is illustrated. 



