When these lines were penned we had no idea that what appeared an unsolvable problem would so soon be solved. For to better understand the difficulties in the way of successfully making a reflex camera with an efficient diaphragm shutter it must be remembered that light comes into the camera, not only through the lens, but also through the ground-glass finder on the top of the camera. In the Focal-Plane type the lens is always open and the reflecting mirror acts as a cover for the ground-glass finder while the shutter is released, and consequently only light passing through the lens can reach the plate. To dispense with the Focal-Plane shutter.
The Seven Problems were as follows : 1. That the lens should be open when the mirror was down and the shutter set.
2. That no light should reach the plate through the lens while the mirror was in motion.
3. That no light should reach the plate through the ground-glass finder while the mirror was opening.
4. That the shutter should work at any desired speed without loss of time after pressing the release. .
5. That the shutter could not be set when the mirror was up.
6. That the shutter must of necessity be set when the mirror was down.
7. That the shutter must work equally well when the rising front was in use and also when at any focus.
We discussed the problems with Mr. Arthur S. Newman, whose reputation as an originator of apparatus of the highest quality is world-wide, and he has overcome every difficulty in so simple and satisfactory a manner that it now seems almost impossible to realize that there was any complexity in the work which was undertaken.
In the Newman and Sinclair Patent Reflex there are no blinds whatever, and it embodies everyone of the points suggested above as necessary for the perfect Reflex.
Type 5. Focal Plane Folding Cameras. The general design of these cameras follows that of the Zeiss " Palmos " and Goerz " Anschutz," and they are particularly favoured by professional photographers who have to take pictures of rapidly moving objects for press purposes - in fact, to a professional doing such work, a camera with a Focal Plane Shutter is an absolute necessity. These cameras are compact and can be used with dark slides, changing box, roll holder or Film pack adapter. Of course, anyone purchasing these cameras must recognise the limitations of the Focal Plane Shutter. It is admirable for high speeds, but not good for slow ones ; tends to make dust and has not the life of a diaphragmatic shutter.
The available amount of rising and cross front on this type is small, and although such cameras may be used on a stand, they are really designed for high-speed hand-camera work.
Type 6. Pocket and Compact Forms. Certainly the most portable of all small cameras are the " Goerz V.P. Tenax," " Zeiss Bebe," " Block Note," " Vesta," and " N. & G. Baby Sybil," and these, when fitted with the Zeiss or Goerz Lenses, give perfect negatives, which, though only 1 3/4 x 2 5/16 in size, will stand an enormous degree of enlargement. It is really astonishing to what an extent the small plates taken with these instruments will enlarge.
Most of these cameras may be had of similar construction but larger in size, and those taking plates 3 1/4 x 2 1/2 are very popular. There is a large sale also for such sizes as take plates 4 1/4 x 3 1/4 and 5 1/2 x 3 1/2.
Type 7. Universal Cameras for Hand or Stand, of which the best known are the " Sinclair Una " and the " Sanderson." These cameras consist of a box with folding baseboard which, when opened out at right angles to the body of the instrument, supports the lens-carrying front with the bellows attached. Such cameras are light and fairly compact, and their available range of movement is greater than that of any of the other forms, and consequently they are very suited to the worker who wants to do the best work whether in hand or on stand.
The advantages of this type when properly made are as follows :
Almost any lens can at will be used and changed instantaneously for one of a different focus.
The range of movement permits of a great rise being used - an important matter in architectural photography.
They are well adapted for Tele-photo work.
Any shutter, including Focal Plane, can be used, the latter preferably as a supplementary shutter.
Any plate or film-changing device can be fitted, consequently the same camera is suitable in all cases.