No. 3340. Beck photomicrographic camera, complete with one double dark slide, 
+-plate, 34in. < 44 in. size ... des sae on Sat aa = CLS CuO 
The camera has an extension of 30 in. It consists of a steel hexagonal bar supported on 
four levelling screws. Along this bar slide three frames with connecting bellows, each frame 
being provided with a clamp screw. The frame at one end holds the ground glass and double 
plate holder, the frame at the other end carries a flexible bag to attach to the microscope. By 
means of the levelling screws, the centres of the camera can be adjusted at any height from 5? in. 
to 7} in. 
No. 33408. As No. 3340 but with reversing back to camera and exposing shutter ... £9 19 6 
No. 3339. Beck photomicrographic camera, complete with one double dark 
slide, 4 plate, 6442 in. size ... ane ra aie aaa ee 1555020 
This camera is in the main features similar to the No. 3340. It, however, has a total 
extension of 36 ins. and is provided with a reversing back and exposing shutter. An extra 
front panel is also provided to which can be attached a short focus lens when it is desired to 
take low power photomicrographs. Four sockets are supplied to screw on to bench, into which 
the levelling screws fit. 
MICROSTIGMAR LENSES. 
This series of lenses have been specially designed and 
corrected for photomicrography. They are found extremely 
useful when it is desired to take photographs of large objects 
at low magnifications. The working aperture is f/4°5, and the 
mounts have the standard Kk.M.S. gauge of screw. 
No. 2994. 40 m/m focal length ... ac Bra eb lley (0) 
No2995.- 50. ;, > ae eee Bae ae 615 0 
No. 2996. 75 of ms a waite et coe 615 0 No. ae : 
No. 33438. Achromatic focussing glass sat as ues too OD 20 
This consists of a high-power lens mounted in an adjustable tube, which can be set so that 
when it is stood upon the ground glass the latter is sharply focussed. A small portion in the 
centre of the ground glass screen of our cameras is left clear so that the image can be 
viewed with the focussing glass without being partially obscured by the ground glass. 
The method of setting the focussing glass is as follows: Loosen the top cell which holds the 
lens combination by slightly unscrewing it, then screw the outer one of the tubes downwards 
away from the cell, leaving the screw of the top cell exposed. Now hold the inner tube and 
screw the top cell backwards and forwards until a pencil mark on the lower side of the ground 
glass is sharply defined, while the focussing glass is held against the upper side. Then screw 
up the outer tube, which will form a lock nut and fix the top cell in the correct position. 
No. 3348A. Focussing glass, of simpler type, and without clamp ring ... 238 so0 | ede tbe Le 
o2 
