Some Notes On Print-Meters

           Of the many forms of print-meters, or actinometers, the type dependent upon miniature negatives of graduated density is preferred by some, as no matching of tint is required, and for occasional work with only a few frames exposed it certainly is convenient. On the other hand, the most accurate of all probably is the "single-tint" tint-matching type, almost essential when many frames have to be kept going and taken in and out during the day's work, but it requires constant inspection, and if one tint is over-done accidentally only a rough estimate is possible to compensate for the over-printing. Single-tint meters, such as Johnson's, supplied by the Autotype Company, are provided with a roll of P.O.P., which under varying atmospheric conditions does not always make a good match: with the surrounding tint, the yellow glass above necessarily being of insufficient depth to remove colour contrast. Greater accuracy in reading is secured by not attempting to effect a colour match, but to work in the following way: If the nearest edge of the rectangular aperture is viewed obliquely from a fair distance with the eyes partially closed, it will initially stand out lighter than the darkening silver paper beyond it, and at a certain stage will merge into the tint and be lost, which point is taken as "one tint." Tests have shown that this method largely eliminates the personal equation, one printer, practically speaking, registering the same number of tints as another, whereas in the case of colour matching by gazing directly downwards on the meter wide differences in the estimation of what constitutes a tint have been found. A variant of "Johnson's" is the circular meter with disc refills: it is cheaper, but for professional use the former is the better. In some cases celluloid is used to protect the tint, but it is an indifferent substitute.
           To insure accuracy with thin or medium negatives, the meter should register three or four tints during the printing, accuracy being of more importance when printing platinotype or palladiotype by meter than with the carbon process, which has greater latitude in exposure, or, rather, errors in exposure are more readily corrected in development. But a quick-printing single-tint meter is a decided nuisance when dense negatives are being dealt with, and in such a case a fixed-out lantern plate dyed yellow with bound-on cover-glass can be placed over the meter and will be found very useful to slow down its indications. As a matter of curiosity, it may be mentioned that the extreme variation in the rate of contact printing met with in one trade printing concern ranged from three minutes to twenty hours, the negatives - being exposed to the same

mercury light, and each negative affording good prints. The perpetrator of the twenty-hour gem had "faithfully promised his customer a dozen prints at the end of the week," as is usual in such cases.
           Other forms of print-meters based on tint-matching are illustrated by "Sawyer's" and the "Akuret," the sensitive paper being exposed under translucent tints of different densities. They possess an advantage over the single-tint type, as no movement of the paper is required whilst the negatives are being printed, but their scope is not so wide. The familiar Wynne's meter, dependent upon numbers successively printing out, is a favourite with many, though others experience a difficulty in deciding whether any particular number hat, or has not, appeared Finally, the type first alluded to is the device of Mr. H .J Burton, on the lines of which the making of an efficient home-made article is to be described.
           Not a few have attempted to make print-meters of the graduated miniature negative order, by copying a photograph in the camera, or by exposing by contact a dry-plate behind a positive, in either case successively on different parts of the plate, with an increased time of exposure for each small negative, but this method is very uncertain, and the results are usually far from satisfactory for fairly obvious reasons. It is also obvious, when mentioned, that to attempt to design a meter capable of indicating exposures from thin negatives up to those of extreme density, either means an undesirable multiplication of the tin; guide negatives, or an equally undesirable abruptness in the translation from one to another. For unnaturally dense negatives, one or more pieces of ground-glass placed over the meter will meet the case.
           Fig. 1 represents a quarter-plate negative of nine prints stuck on white cardboard, which are reduced by copying in the camera to a little less than 2*(1/2) inches high over all, in position shown on the plate. The prints should be of the same subject, preferably a portrait rather large on the plate, and whilst it is an advantage that the set be uniformly lit, even illumination is not essential. Over-exposure is to be avoided as bright, but fast printing negatives with almost clear glass shadows are the moat suitable. If the ground prints through it is blocked out.
           Assuming the figure to represent the glass side of the plate, and the negatives to read from left to right in the usual way, the graduation in printing rate is effected by covering No. 2 with one layer of celluloid, about the thickness of that used for cut films, No. 3 with two layers, and so on. Fig. 2 shows the first sheet of celluloid applied with extremities extending beyond the miniature negatives,

but clear of the edges of the glass; on the right about 1*(1/3)th inch, on the other three sides more space is available. The next sheet has space 2 cut away, and is stuck down at each end with a touch of celluloid varnish, the procedure being continued mutatis mutandis until No. 9 is covered with eight thicknesses.
           When the first test of the meter is made everything may appear right, the lower numbers being nicely graded, and on printing further the faint images of the highest numbers apparently the same. But here exists an unsuspected trap, for on printing, say, No. 5, to the "pretty" stage, No. 6 may now be found to be almost indistinguishable in depth, and therefore require further ho. ding back, together with the numbers following it.
           Accordingly, the only safe plan is to test each number right through the series at its "pretty" stage against the next less printed one. Some pieces of stripped thin roll- film may be found of service when only a very slight holding back is demanded. The celluloid covering is then edged all round with cardboard slips stuck down with seccotine, and a thin cover-glass bound on. If the lower numbers print too quickly for the negatives in use, the cover-glass may be of ground-glass. A three-quarter-view quarter-plate printing-frame holds the finished article; white wood frames are sold sufficiently deep to take it. A packet of 3*(1/2) x 2*(1/2) ordinary gelatine P.O. P. provides the meter paper, and will keep for years if stored in an airtight tin with some dry calcium chloride. Self-toning papers are not so good for the purpose. When the number indicating the correct exposure is found by trial, naturally only a narrow strip of paper need be utilized afterwards.
           In the model constructed, which has worked well, for identical depths of printing the last number requires about six times the exposures of the first, a range sufficient to satisfy most requirements. This ratio, of course, only holds good for the particular thickness of celluloid employed. Comparative values might be given each negative if a single-tint meter is at hand, or improvised, by registering the number of tints necessary to bring each negative in turn to the pretty stage.

Practicus In The Studio: Studio Exposures.

            Correct exposure is one of the most important of the factors in making perfect photographs, yet the majority of portra approach it in the most casual manner, and apparently trust to a sort of sixth sense to tell them how long to keep the shutter open, or as one Mid to me, "It is like taking a dire into water; when I press the bulb, I do not know when I am coming to the surface.” With long practice it is possible to work successfully in this sab-conscious way, but most people will find it desirable to have some definite idea of the number of seconds necessary to give the exact quality of negative which is aimed at. I want you to take particular notice of those last words. There can be no fixed standard of exposure or density in portrait work, or we should all arrive at one monotonous style, without that touch of individualism which now distinguishes our best photographers from one another. Twenty or thirty years ago there was an established ideal of a clear, sparkling negative ranging from clear glass to opacity, and a high-class operator who did not conform to it had little chance of employment. Many negatives which would be appreciated to-day were then thrown aside as failures, because they were too soft or too hard to print in the limited range of media then available, but now we are more free to choose our methods, and can produce negatives to satisfy our own artistic instincts. Therefore it is necessary if we are to be consistently good in our work we must not trust to "flukes" for our successes, but to study the conditions under which our particular class of negatives can be obtained.
            On asking one of our best known outdoor photographers bow he secured such uniformly perfect negatives. I was told that they were obtained by "exposing to suit the developer.” This was in the pre-Watkins days, when no attempt had been made to systematize development and most people believed that the clever worker owed his success to modifying the developer according to the appearance of the imago, often beginning with plain pyro solution, and working up the negative by adding alkali and bromide drop by drop. This idea is now exploded, proving that my friend was a true prophet when he asserted that the prime factor in producing the negative was correct exposure Hurter and Driffield, to whom photographers owe so much, have taught us that the amount of silver affected by light when a plate is exposed is in definite proportion to the length of exposure given, bat this assumes that all the so affected is reduced by the developer, or, in other words, the plate is “developed right out," which is rarely the case in studio work, most portraitists finding that such a procedure produces too much contrast. This fact has been recognized by both plate and developer makers who prescribe different times of development for portrait, landscape and copy negative, the former always being much shorter than the latter two.
            To establish a correct method of exposure we must make a few experiments, working with a standard developer, and a fixed time of development, which may be obtained by the factorial system, the only variation being made in the exposure. It is convenient and economical, besides assuring uniformity of rapidity in the emulsion, to make several exposures on one plate, and this can easily be done in most studio cameras by fixing a small mask in the camera back and marking the slide so as to show when the plate is in position. The easiest size is to work three upon a half-plate, cutting a mask with opening two inches by four and fixing this in the existing carte or cabinet mask. If the slide has notches for single exposures, and also for repeating two C.D.V. on half-plate, the centre notch may be used, but new marks s little farther from the centre must be made for the two end exposures. For my own use I have made a repeating back which allows of four exposures, each three inches by two clear, from the rebate upon a half-plate, and this I find handy for many other purposes.
            The exposures, which must, of course, be upon the same subject, may be varied in any proportion which the operator desires. Usually double at each step will be found as good as any for portrait work, as our negative will then show us the effect of one, two, four, and eight seconds' exposure. The result will be rather surprising to those who try it for the first time; for, supposing that the one-second exposure gives a thin but printable negative, it will be found that the eight-seconds section, although thick and slow to print, will also yield a passable result. That, however, is not my point, which is that the operator should now select the exposure which gives him the quality of imam- he wants, or if none quite pleases him should give an exposure between the two which he judges to be nearest correct. So far so good. Now all depends upon correctly estimating the value of the light, and this can better be done with an exposure meter than by the exercise of personal judgment. If we use an ordinary Bee meter and note the time taken to match the tint at the. time of making our exposures we shall be able to establish a ratio between meter time and exposure for any light or lighting. For example, if we find that our selected exposure is four seconds, and that it took right minutes to get the tint, we haw the proportion of half a second for each meter minute. Naturally I do not propose that anyone should make meter tests while sitter waits, but an occasional test between whiles can easily be managed. The plate speed and lens aperture must be unchanged, or due allowance must be made, or this system will be worse than useless.
            It is often found that when strong effects of light and shade are being tried for that the negatives turn out hard and chalky and do not at all represent the model as seen by the artist. There are two causes of this, both closely connected, under-exposure and over-development, the latter being due to an attempted to force out shadow detail. Now, if development had been done by time without regard to the appearance of the image, we should have retained the detail in the high lights, but the shadow detail would still have been wanting. Longer exposure would remedy this without giving flatness, unless-unite an unreasonable time were given. This class of subject affords an excellent field for the progressive series of exposures already recommended; or if it be thought that the effect cannot be judged from so small s plate two full-sized exposures may be made, one receiving three times as long as the other, both being developed for the same time in the same dish.
            It is important when making experiments in exposure to keep not only to one make of plate, but to the same grade. Emulsions vary in character, and two grades which are, perhaps, marked 200 and 240 H and D, cannot be relied upon to give the same quality of image, even if the difference in speed be accurately allowed for; much more is this the case if two makes of plate he mixed up. For the same reason one developer should be adhered to, and for printing quality land adaptability to various subjects and lightings there is nothing to beat the old-established pyro-sods. Remember that a negative is only a means to an end, and that "pretty" negatives do not always give the best of prints. Although not strictly within my subject, I feed that at the present time of year it is not amiss to on that pyro is less affected in its action by variations of temperature than most other developing agents. I have only recently found the slow action of another developer mistaken for under exposure, with the result that the exposures were increased and flatness resulted.
            A point which mart not be missed is the effect of the distance between lens and sitter upon exposure. This is always allowed for in copying, but is often overlooked in portraiture. Most operators know that a large head requires more exposure than a full length, other things being equal, but perhaps could not toll you why. There are two reasons, one being the increase in the focal length of the lens a the sitter approaches the camera, and the other the flattening of the lighting by the greater amount of atmosphere which intervenes as the sitter is placed further from the camera. Let us consider the former case, assuming that a head measures 9 inches in height and we are making a 3 in. image of it: this adds one-third to the camera extension, supposing we are using an 18 in. lens working at F/6 for infinity; one-third added to the focal length gives us 24 ins - in other words, we are working at F/8, which requires practically double the exposure. When taking a full-length cabinet the reduction would be l/12th, which would only add an inch and a half to the original focal length, and this we could safely ignore so far as exposure is concerned. In the second case the increase in exposure is only apparent, not real. If there is a certain amount of fog over the shadows it covers the bare glass, but there is no more detail in the shadows than there would be if the atmosphere were perfectly clear. In London, where the atmosphere is as thick in winter as it is in most places, many photographers use a lens of shorter focal length than they would otherwise, in order to avoid this flattening.
            In conclusion, let me impress upon the notice that correct exposure is the key to satisfactory results. Leaving colour effects out of the question, any arrangement of light and shade can be correctly reproduced if the proper exposure be given. We can flatten the scale by over-exposure, we can sharpen it by under-exposure, so that if we hit the happy mean we shall get upon our negative what we saw when looking at the sitter. Surely such a consummation is worth taking pains to attain, instead of following the usual "hit or miss" way.

PRACTICUS.