Tuesday, May 20, 2008

EX CATHEDRA: Ghost Images or Flare, Camera Copies and The Shop Window.

Ghost Images or Flare

It is a known fact that many of the finest pre-war anastigmats frequently give both ghost images and flare when dealing with subjects which throw a strong light into their glasses. The defect is much lees often met when single lenses or the single components of convertible auastigtmats or R.R. instruments are employed. "Ghost images" or "flare'' are regarded by many photographers as being the more likely with instruments having many glass-to-air surfaces, and as a matter of fact, though not as a general rule, the more of these surfaces there are in the instrument the more likely is the defect to be in evidence in certain classes of work. It is not realized as well as it might lie by those who possess anastigmats which exhibit flare or ghost images that much may be done to assist in eliminating these if the instrument is provided with a sufficiently deep hood. We have in our own possession an anastigmat with no less than ten glass-to-air surfaces, and invariably when this lens is used against the light or under like conditions the defects are sure to manifest themselves, yet when the front glass is shaded with a deep and efficient hood we have never had the least reason for complaint. The rarity of ghost images or flare when R.R. or single lenses are used may be traced in part to the fact that with the former class the hoods are much more efficient: as regards the latter, when the single components of the convertible anastigmat are employed it is nearly always the front lens that is removed, and thus the mount of the lens serves as a highly efficient hood for the back glass.

Camera Copies.

The recent installation of the Photostat Patent Office brings forward the subject of quick and cheap copying of documents, printed matter, or drawings, by means of the camera. As most of our readers are aware in this and similar apparatus, the print is made by exposing bromide paper in a special camera which is scaled to various sizes. The image is normally a negative one, although positives may be made by recopying them same size. Taken in an ordinary camera the images would be laterally inverted, but this can be obviated by fitting a reversing prism or mirror to the lens, the latter being, of course, much the cheaper arrangement. We think that photographers who work for engineering and other manufacturing firms would do well to take this class of work into consideration, as it would secure many orders for copies of drawings, plans, etc., not amenable to duplication by the usual heliographic methods, which call for a translucent original. It should not be difficult to arrange an attachment to any ordinary large camera for moderate-sized subjects, while larger ones could be managed by taking a small negative and enlarging in the usual way. We have seen some excellent copies up to three feet across made in this way and as the work practically mechanical, highly-skilled labour is not necessary. On point is essential, and that is that the same lens should be used both for making the negative and the enlargement. The operation has been very successfully carried out thus: supposing an architect's drawing has to be reproduced, a copy is made upon a process-plate, say, half-plate or whole-plate size, the distances between lens and original and lens and plate being accurately measured. The lens is then transferred to the enlarger, and the negative and bromide paper carefully placed at exactly the same distances, the result being a full-sized copy free from any distortion, the image having been made to travel back through the same optical system by which it was produced. Where much work has to be done it would be well to have both camera and enlarger rigidly set to the required points so that for full-sized reproductions no setting would be necessary. With a proper artificial lighting scheme the exposures of both plate and enlargement would be a fixed quantity, and a spoiled sheet almost unknown.

The Shop Window.

A few days ago we were asked whether it was advisable to retain a shop window for the display of specimens or to be satisfied with show-cases in a lobby and let off the shop. This is not quite such a simple question to answer as it appears at first sight, since many factors have to be taken into consideration. The first of these is the class of business which is intended to be done. The highest class of portraitists depends almost entirely upon introductions and to a lesser degree upon reproductions of their pictures in the press. Some go no farther than a brass door-plate to advertise their locale, a few even dispense with this, while others have modest show-cases with only one or two specimens on view at a tine. A few of the older firms have large lobby shows or shop windows, but it is not until we reach those who cater mainly for chance trade that we find the window show really popular. Recently there has been a great increase in these window shows in London and other large centres, so that we must conclude that they have been found to be a paying proposition. It may be noted that many of the large portrait shops are being run by people who are also engaged in other branches of industry, and they have treated photographs in the same way as they would clothes, jewelers, or tobacco. Surely, therefore, it is quite in order for the photographer, pure and simple, to take a leaf from the business man's book and to go in for bold advertisement, providing that he has the means to do it properly, and not to lose sight of the next important factor in the matter that of locality. To be effective a window display must be situated where there is a considerable amount of traffic, and in what may be called a shopping or market thoroughfare, where there are other attractions. Even in the same street one position is valuable and another almost worthless. In nearly every important thoroughfare there is one side which is much better for business than the other, and this keen business man is careful to ascertain before he invests his money.

No comments: