When it is required to obtain a large image with a small lens, a stop with a central aperture (which may be readily made of a piece of circular cardboard blackened with Indian ink) must be placed in front of the lens. This will diminish the amount of light, but will render the picture more distinct towards the edge, and bring a variety of objects at different distances into focus at the same time. With a stop attached, the lens may also be brought nearer to the object without distorting. With regard to this subject of the distortion often produced by lenses, observe particularly, that with the portrait combination of full aperture, and especially when the powers of the glass are rather strained by its being advanced too near to the sitter,--all objects near to the lens will be _magnified_, and those more removed will appear diminished; hence, as the position of the sitter is never quite vertical, the Camera must be inclined a little _downwards_, or the hands and feet will be enlarged, the figure in fact becoming pyramidal with the base below; whereas on the other hand, if the inclination of the Camera be too great, the head and forehead will be enlarged, and the figure becomes a pyramid with the base above. When groups are taken, arrange the objects as near as possible equidistant from the lens, and use a stop if practicable. Long-focus lenses are the best for this purpose, allowing the Photograph to be taken further off, and giving a greater variety of objects in focus at the same time. Portrait lenses may often be advantageously substituted for View lenses in copying objects of still life which are _badly lighted_. The aperture of the lens being large, a Negative can be obtained with an amount of light which would not suffice if a small stop were used. On the other hand, if the light be unusually bright, the lens of full aperture is always the most likely, from its extent of reflecting surface, to produce a misty and indistinct image. Hence the object should be well backed up with some neutral colour, or, if that cannot be done, a pasteboard funnel, projecting about a foot and a half, may be fastened in front of the lens, in order to exclude rays of light not immediately concerned in the formation of the image. If the lens were turned towards distant objects brightly illuminated, and a portion of sky included, there would probably be diffused light, and consequent fogging of the plate on the application of the developer. This effect will also invariably follow if the sun's rays be allowed to fall directly upon the glass.