imperial orthochrome plates.

IMPERIAL ORTHOCHROME PLATES.

"SPECIAL SENSITIVE ORTBOCBROME" (H & D. 275).

"SPECIAL RAPID ORTBOCBROME" (H. & D. 200).

"N.F. (NON-FILTERi ORTBOCBROME" (H. & D. 200).

SPEEDS.

"SPECIAL SENSITIVE ORTHOCHROME" plates. with a speed of 275 Hurter & Driffield system, are the most sensitive Orthochrome plates at present made. They are rapid enough for Studio use, and will allow of instantaneous exposures with a two or four-times Filter in good light outdoors, and at any time without a Filter. For work in difficult situations or poor light use this brand,

"SPEPAL RAPID ORTHOCHROME ·• plates (H. & D. 200) are suitable for snapshot exposures with a two or four-times screen in the best light of Spring and Summer outdoors ; but this plate is par excellence the plate for Stand-Camera users, who ai:,reciate its brilliant qualities, and can without inconvenience give the comparatively lengthy exposures necessary when a deep filter is used.

"N.F." (NON-FILTER) plates (200 H. & D.) For all purposes, whether with hand or stand camera, where orthochromatic results are desired with the least possible trouble, these plates are without a rival.

Not only is the time of exposure brought within the limits of the cheapest hand-cameras, but there is no Light-Filter to trouble with, and no fear that the crispest definition will be interfered with •

. BACKING (Anti-halo).

Imperial Ortbo~hrome plates are supplied "backed" at the usual alight extra prices; the outlay is well repaid in the improved quality of the negatives, Even in subjects which do not include violent contrasts of light and shade a "backed" plate shows a striking improve- ment in the rendering, the delicate gradations of the picture being preserved, and halation entirely avoided, The Imperial backing is applied by an improved method; it will not chip or rub off. and so cause spots in the film, and being perfectly soluble it is not necessary to remove it before the plate is developed.

NOTE.-ln some cases there is a mistiness or hazy appearance in the subject itself, or the atmosphere round n window or other high- light in the subject may be rendered luminous by sunshine on mist or floating dust. A "backed" plate will not eliminate this, but it will minimize the trouble and give a much clearer image than an unbacked plate would do under the same conditions.

FOR EWORD.

T1-1E object of this little booklet is to explain to the amateur photographer wherein lies the difference between an Orthocbrome plate and a Non-Ortho- chrorne plate, and to illustrate by a few pictures how coloured objects are rendered by the two classes of plates.

There is no doubt that for some subjects Orthochrome plates offer decided advan- tages: they are particiilarly useful in landscape photography in Spring and Autumn when the foliage assumes such infinite variety of tints, also for Archi- tectural work where coloured stone or marble, stained-glass windows, and so forth have to be photographed, and at all times when it is desired to secure clouds, which on a Non-Ortho. plate usually print out blank. For copying coloured articles and pictures they are indispensable.

As with other Orthochrome plates, Spect~1

cf!d.id

Orth()·_,Goldsmith. it is necessary

t o

have a Light-Filter when Imperial Special Sensitive Ortho.

(S.S.O.) and Special Rapid Ortho. (S.R.O.) plates are used, to secure the full benefits of their Orthochromatism, but the Non-Filter (N.F.) plate is unique as regards its Orthochromatic properties. Its sensitiveness to yellow and green has been raised to such a point that it may be used without a Filter for all average subjects, and a filter is only necessary when subjects including great colour coutmsts have to be photographed.

NORTH AISLE,

WINCHESTER CATHEDRAL.

It must not be forgotten that the use of Orthochrome plates is not confined to the photography of such subjects as mentioned in the last paragraph; they are suitable for all subjects, and when used without a light-filter will do all that a non-orthochrorne plate will do.

vVe need hardly enlarge on the position Imperial plates hold in the photographic world. By their high quality and reliability under every condition they have taken the premier position, and are well known and appreciated not only in Great Britain, bu-t in every country in the world. A position of this kind is not won by chance or haphazard methods, but by close attention to every detail of manu- facture, by using only the very highest class of materials, and by rigorous tests of the finished product before it is sent out for use.

Every batch of plates is carefully examined and tested for speed, the correct speed-number being stamped on each box of plates.

\Ve confidently ask our friends to test our plates in comparison with any others, when they will not be found wanting, either in speed or quality.

THE IMPERIAL DRY PLATE CO., LTD,

IMPERIAL ORTHOCHROME PLATES .

The practical photographer very soon learns, to his surprise and disappointment, that the beautiful white clouds against the glorious blue-sky background which crowned his landscape are often conspicuous by their absence in bis print, although at times there may be some indication of their presence in the sky part of the negative. In fact it is quite a commonplace saying that '' blue photographs like white.'' Certainly this often was the case in the earlier days of the art, but assuredly it need not be the case now, for the introduction of the orthochromatic (or colour-correct) plate enables us to show various colours in the order of their true relative brightness, in our black-and-white prints. Thus a white cloud against a blue sky appears lighter and brighter than the sky, and so when translating both into black-and-white, or any one colour

(i.e., Monochrome), the white cloud should appear not necessarily

blank white paper, but decidedly lighter than the grey or other tint which represents the blue-sky background. As a matter of fact clouds are seldom quite white, but the fact that they are of a very pale yellow or pink tinge, seen against a darker sky background, leads us to think of them as white or colourless.

There is no difficulty whatever in using Orthochromatic plates, for they are manipulated as regards exposure, developing, printing, etc., just like ordinary (i.e., non-ortbochromatic) plates.

But the foundation fact that they are more sensitive to certain colours than are ordinary plates obviously calls for a little extra care in the matter of the light used in the dark-room. All we need is a good ruby lamp and reasonable caution against ex- posing the plates nearer to the lamp or for a longer time than is absolutely necessary, when loading the plate-holders, develop- ing, etc.

A few homely and simple experiments which anyone can make will do more to put the reacjer on the right track, than reading pages of a high and dry scientifi\: treatise. Our needs are an ordinary camera, a few ordinary · and a few Ortho. plates-say one box of each kind- and a yellow " light-filter" or "colour- screen.'' Our object is to ascertain what difference precisely is obtained by using an ordinary and an ortho. plate side by side on the same-coloured objects. As white clouds and blue skies are not always available for experiment we may substitute any other blue- and-white objects,

In figures r and 2 we have a group of white-and-blue earthen- ware plates. They have been selected as showing six different kinds of blue, all of which bear a fairly close resemblance to the various shades of blue which we see in our sky at various times of the year. It will be usefnl not only in connection with blue skies, but other blue objects-e.g., flowers, costumes, etc.-to try and realize the kinds of blues of these six plates.

2

(A).-Top centre, old Dutch plate, ultramarine blue and bluish tinge of glaze.

(s).- Top right, Nankin plate. This blue is that commonly called deep sky-blue.

(c).-To left, ~Id Oriental plate. Tl1is is the companion pale

· sky-blue.

(o).- Centre bottom, old Leeds plate, deep powder blue as used in laundries.

(E) & (F).-Bottom right and left. Modern Wedgewood of the

familiar "onion" pattern. On the right a dark purple blue. On the left a decidedly light tint of the same colour.

In figure I we have the result obtained with an ordinary plate, while in figure z we have the result of an Ortho. plate and "four times" colour-screen.

This experiment shows us that while the ordinary plate does discriminate between white and deep blue, there is not much difference between white and pale blue; while the Ortho. plate shows not only far more natural light-and-shade contrasts, but also discriminates between the various blues.

The reader will probably ask how it is that the ordinary plate (figure r) shows as much difference between white and blue as it does, while the blue sky and white clouds both come out as white paper in his prints. There are two reasons for this. In the first place the blue colour of the sky is really generally mixed with a good deal of white light, so that while it looks rich blue it is really very light- as we can see for ourselves by comparing it with any light blue object held at arm's length. Also in figure r the exposure was adjusted for these white-and-blue plates quite near the camera, while in landscape photography we have nearly always to adjust our exposure for the more important foreground objects;

so that relatively the sky part is exposed ten or twenty times as long as should be the case if the sky were the only thing to consider.

In fact the sky is usually over-exposed, and so the contrasts of the white clouds and blue sky suffer proportionately.

"Why need we use a Colour Screen?" is a natural question to ask. Briefly and crudely put, the reason is that the ordinary plate does not ''see'' or respond to various colours in quite the same way that the human eye sees them. For example, the plate is strongly affected by blue rays-so that, as we ha\'e just seen, blue prints out lighter than the eye regards the colour. vVhile the eye regards the yellow of a buttercup flower (for example) as a light colour, the plate '' sees'' yellow as a dark colour compared with blue. Consequently, in order to make the plate regard the bright- ness of colours in the same order as the eye regards them, we have to stop or filter out some of those rays which act too energetically on the plate, so as to give the slow-acting rays a chance in the race.

In fact a colour-screen handicaps, as it were, the various coloured rays of light.

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But this is not quite all, for unfortunately there are certain rays of what we may call invisible light reflected by many objects- i.e., rays which the eye does not perceive, but which affect the plate to a considerable extent. These invisible but active rays are closely related to those which we call blue and violet, and so are called ultra

violet rays. ·

Now a colour-screen or ray:filter, to be efficient, must stop out all the active eye invisible or ultra violet rays, and also stop some, but not all of the eye-visible rays of those colours which act on the plate more powerfully than they do on the eye, so that all may be brought to eye standard. It will thus be seen that any odd bit of yellow glass will not be able to handicap the various rays properly.

On the contrary the particular tint has to be accurately adjusted to suit the sensitiveness of the plate. It is therefore highly desirable to use the colour-screens recommended by the plate manufacturers.

It might naturally be thought that all one needed was an ordinary plate and a colour-screen, but this is not the case. For not only does the ordinary plate see some colours too light-e.g., blue, violet- but it also sees others too dark- e.g., yellow, red, etc. The con- sequence is that the sensitive emulsion spread on the glass has to be stimulated into activity by dosing it with certain chemical substances which increase its vision in certain directions. The plate is thus said to be '' sensitized '' to those colours. Such a plate is usually designated orthochromatic, or sometimes isochromatic.

It is true that we can use an ordinary plate and colour-screen, but, except under very rare (and practically negligible) circum- stances, there. is no advantage in the result, while the time of exposure is inconveniently lengthened. But if the plate is colour- sensitized-i.e., orthochromatized-and a suitable colour-screen be used, we get a twofold advantage- e.g .. the over-active colours are duly held in check while the special colour sensitiveness of the plate brings the otl1er more slow-acting colours into line. For these advantages we have to pay something-i.e., the time of exposure is longer than if no colour-screen had been used. The screen may double, treble, quadruple, etc., the exposure; thus a screen may be designated a "lour-times" screen, and so on. This is sometimes written with a sign of multiplication-e.g., " x 4" (or other time factors as the case may be). The Imperial Dry Plate Co.

make three colour-screens for use with their brands of Ortho.

plates. The lightest yellow is a "two-times," and the darker ones are '· four and eight times.·'

There is yet another way of meeting the case- viz., by com- bining the effect of the colour-screen with the orthochromatized coating of the plate. The Imperial Dry Plate Co. issue such a plate, which is designated" N.F. "-i.e.," Non-Filter "-for while it is an Ortho. plate it does not require the user to add any colour-screen to his lens, as is the usual course with Ortho. plates in general. The advantages of such a plate are too obvious to need recital. These plates are especially valuable for hand camera work.

6

FIG. 5.

F1G. 6.

7

_J

The efficiency of the" N.F.'' plate is exemplified by figs. 3 and 4.

·one need hardly point ciut that fig. 3 gives the result obtained with an ordinary plate, while fig. 4 shows the effect got by the "N.F."

plate. The background is a weather-stained oak paling oYerhung with Virginian creeper, showing a fascinating play of autumnal tints in green, yellow, orange, and red bathed in sunshine. In the former case the effect is comparatively tame and uninteresting, as the variously coloured lea,·es come out all very much the same tint, while the background looks lifeless and dull. In the latter case not only does the background convey some texture as well as sunligbt effect, but there are scarcely two adjacent leaves of the same tint, while seYeral large lea,·es near the centre which were of rich shades of greenish and golden yellows and pale orange properly come out the most conspicuously.

vVhile this foliage study is perhaps more attracti,·e than a group of plates or any similar still-life subject, yet such nature studies, on account of superabundant detail and the small size of the objects as depicted, do not bring home to the mind the

"bottom facts" in quite the same straightforward way that a more simple and familiar object does.

The reader may therefore ad,·antageously put out of his mind any picture-making thoughts for the moment, so that we may make a second experimcut with another homely subject. This time we invest the sum of one penny in a tiny tin of mustard, selecting one wbich shows a small Union Jack on the outside. Vve also should raid the kitchen or garden for a sprig of parsley. Cover the table with a sheet of white blotting-paper and fix up a black background- e.g., black ,·eh·et focusing-cloth.

First take careful note that in addition to black and while we have green parsley, the tin covered with ytllow paper upon which are letters printed in black, and also the flag showing dark blue triangle, -red stripes and white stripes.

First we employ an ordinary plate, and get· the result shown in fig. 5, where the black letters on a yellow ground are practically invisible; the dark blue triangles come out too light and the green parsley too dark.

Now we use an Ortho. plate and the darker (eight-times) screen, and get the result shown in fig. 6, where the black letters are now well seen on a pale ground.; the blue triangles are now darker than the green parsley, as should be the case, while the red and white stripes are well contrasted, and we see the price of our model is proclaimed to be one penny.

vVe may next try an experiment with a white narcissus having a yellow inner part or corona, a dull-surface light green leaf on our left, and dark green shiny leaYes on our right. First using an ordinary plate we get fig. 7. where the yellow corona is very much too dark, and the two greens are too indefinitely dull and dark. But using an Ortho. plate and four-times screen we get the yellow in true relationship, while the difference between the light and dark green is well suggested.

8

FIG. 7.

FIG. 8.

9

Finally we may compare the effect of the ordinary and Ortho. plates in the case of a summer sunlit landscape subject, where the sky part occupies a conspicuous and important rart of the composition, snch as is depicted in figures 9 and IO. In the former the sky space is blank; the foreground green is too dark, while that in the distance is too light, and is more like sand than grass.

The distant part of the landscape is somewhat flat. as though all its parts were at one and the same distance from the camera.

In the latter example, obtained with an Ortho. plate and four- times screen, we notice the sky and cloud part at once. The fore- ground grass is lighter in tone, while the part round about the cricketers looks like grass, and the distant part of the scene, trees, etc., show agreeable modelling and relief.

CONCLUDING HINTS.

r . -1 o matter what light is used in the dark-room, the less any plate, and especially an Ortho plate, is exposed to dark-room light the better.

2.-Negatives on Ortho. plates used by beginners are often somewhat o,·er-developed, owing to the idea that a good negative should always look bright, plucky, and sparkling. Over-development of a negative will obliterate some of its finer qualities, and mask those more delicate and subtle gradations and differences which the trained eye appreciates.

3.-An Ortbo. plate will do all that an ordinary plate will do if used without acol,rnr-screen, and, used with a colour-screen, will do far more and better than the ordinary plate.

4.-It is sometimes supposed that it is not " worth while"

using an Ortho. plate and screen except for brilliantly coloured objects. This is a mistake, for very nearly all objects in nature show some colour, even though it be not very conspicuous; and whenever there is colour present the Ortho. plate has an advantage over the ordinary plate, although the casual obsen·er may fail to notice and appreciate such subtle differences.

5.-Another common error is to suppose that if a pale (e.g., four-times) screen impro,·es the result, a darker screen (e.g., ei⁰-ht times) will give a further improvement. This may or may not be the case. A screen too dark is likely to render clouds . with exaggerated light-and-shade contrast, and suggest storms rather than the effect shown in figure IO. In fact there is a somewhat widespread tendency to o,·erdo the sky and cloud part of land- scapes. On the other hand, when dealing with vi,·id contrasts such as those shown in figures 5 and 6, a darker screen will be fonnd helpful.

The worker will do wisely to be provided with a light and a dark screen. Experience will soon teach him when to use the one or the other, but no hard-and-fast ,·erbal rule can be laid down. At the same time it is advisable to begin with the lighter screen, and use that only until a little experience has been gleaned.

IO

Special Sensitive Ortho.

f/u, 1/Ssec. DRAGON FLY.

I2

J. H. Saunders.

w ~

Special Rapid Ortho. plate, no screen.

Exp. 1½ secs., f/101 Oct. 25th, IO.Jo a,m. "MORNING MISTS." W. J. Martin.

DEVELOPMENT OF ORTHOCHROM E PLATES .

THERE is no more difficulty in develop- ing an Orthochromatic plate than there is in cle,·eloping a Non-Orthochromatic plate;

tbe photographer may use any solution to which he is accustomed and which he finds gi,·es the class of negative he desires.

Personally we have a preference for a Pyro Soda developer made up to the Imperial formula; this preference is in- fluenced by the fact that Pyro costs less than most other developers, and a firm belief that it gi,·es a better printing negative.

However, tastes differ, and if the use,· of Imperial Orthochrome plates prefers any other cle,·eloper, there is no reason what- ever why he should not employ it. Given a correctly exposed plate there is not a great deal to choose between one developer and another. ',,Vhen it is a question of under-exposure we strongly recommend the Imperial " Standard " developer (Pyro- Metol) ; it is ,·ery powerful and will bring N.F. Plate. F. Wilkins. more out of a plate than anything else.

Exp. 1/~o sec, f/8, May 27th, The usual rules observed when de- 3.4o p.m. veloping Non Orthochromatic plates sboulc\

be kept. Thus for under-exposed plates it is a good plan to dilute the developer with an equal quantity of plain water; this doubles the time of development, and allows the fine detail which has been so lightly impressed on the plate by the brief exposure to develop up before the high-lights are blocked up with density.

For o,·er exposure, use a de,·eloper of full strength and develop for the usual time. Ne,·er mind the blackness of the negative, which seems to suggest that development is being over- done. Much over-exposure tends to make thin negatives, and for this reason cle,·elopment may be carried even further than usual so as to obtain as much contrast as possible. Acid fi,·e or six drops of a 10 per cent. solution of Bromide of Potassium to each ounce of developing-bath to act as a restrainer, and use a larger quantity of No. 1 solution than No. 2.

',,Vhen dealing with a number of plates of which the exposure is unknown, it is a good plan to immerse them first in a bath made up of two parts No. r solution and one part No. 2, with fi,·e drops of Bromide solution (10 per cent.) added to each ounce. If the image appears in regular time the cle,·elopment may be finished in this bath. If the image does not appear in clue time, thus indicating under exposure, pour off the developer and acid another portion of No. 2, or e,·en more if required.

>-<

ln

N.F. Plate.

Exp. 4 secs., f/16, Aug. 12th. ]. H. Wootton.

THE SHOEING-FORGE.

If on the other hand the image rapidly gains in intensity, remove it at once and immerse immediately for one minute in a 5 per cent. Bromide solution, which should be kept at hand when developing unknown exposures. Then replace in the developing- bath, to which should be added r5 or 20 drops of Bromide solution.

Vvatch development in this case by looking at the back of the negative, and stop when all the details are visible.

Orthochrome plates are much more sensitive to the action of red light than Non-Ortho. plates; on no account must a yellow light be used.

Care must be taken that the plates are not exposed too much to the dark- room light during development, otherwise fogged negatives will be the result.

" IMPERIAL PYRO , SODA DEVELOPER."

STOCK SOLUTI0'1.

Metabisulpbite of potash ... ... 50 grs. Pyrogallic acid... r oz. Bromide of potassium ... ... ... ... ... 60 grs.

·water (boiled or distilled) to... r2 ozs.

No. r.

Stock solution ... ... ... ... ... ... ... 3 ozs.

\Vater (boiled or distilled) to... 20 .,

No. 2.

ro grms.

83 13

1000 c.c.

150 c.c.

1000

Sulphite of soda (crystals) .. .... ... 2 ozs. 100 grms.

Carbonate of soda (do.) 2 ., roo

Water (boiled or distilled) to... 20 ., 1000 c.c.

For use take equal parts of No. 1 and No. 2.

" IMPERIAL STANDARD " DEVELOPER.

No. r.

Metal .. . . .. ... .. .... .. 45 grs.

Metabisulphite of potash 120

Pyrogallic acid . .. .... .. . .. .. .. . . .. . .. . 55 ., Bromide of potassium... 20 .,

\Vater (boiled or distilled) to... 20 ozs.

No. ^2.

5 grms.

14 6

2 1000 C.C.

Carbonate of soda (crystals) ... ... 4 ozs. 200 grms.

Water tboiled or distilled) to... 20 ., 1000 c.c.

For use take equal parts of No. 1 and No. 2.

After development rinse the negati,·es in plain water and fix in

Hy~ 6ou.

\Vater 1 pint.

An acid fixing-bath may be used if preferred; it has the advantage of stopping the action of the developer immediately and clearing the negati,·e of pyro stain. The acid fixing-bath may be made up as follows:

Hypo 4 ozs.

Metabisulphite of potash 1 oz.

\Vater 20 ozs.

16

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"

Special Sensitive Ortho. plate.

Exp. 1/25 sec., f/11 April 4th, 3 p.m.

LTCI-IFIELD CATHEDRAL.

F. W. Warts.

A WORD ABOUT EXPOSURE .

IT s110uld be borne in mind that upon the correct exposure of a plate depends its success or otherwise as a negative. It is true that careful and special treatment during development will do something to correct errors in exposure, but the fact remains that it is impossible to make a perfect negative from a grossly over- exposed or a grossly under-exposed plate. There are certainlimits between which the exposure may be varied wit110ut greatly affecting the quality of the resulting negative. TJ1ese limits in Imperial plates Me very wide, as will be remembered hy the readers of our 1910 Handbook, in which we reproduced a set of prints from six negatives which had received exposures varying from r to 80 times. Notwithstanding this great difference in time of exposures the negatives were very much like eacb other.

Too much advantage, however, should not be taken of this

"latitude"; rather should endeavour be made to ascertain the correct time of exposure for each subject. Some experienced workers appear never to be at a loss in gauging correctly the value of the light and the requisite time of exposnre with any given stop, but the vast majority feel it necessarv to have some better guide than their own judgment. For such as these the Imperial Exposure Meters and Imperial Exposure Reckoner have been devised, and these handy tools will save their cost in the first week's use. Fewer plates will be spoiled, and the results generally will be superior to those obtained with haphazard exposures.

The Meters and Reckoner referred to are about the size of a card-case, and, therefore, occupy very little room, which seems to be the chief recommendation nowadavs. The Meter is made in two kinds-No. r for Bright Light, such as Outdoor Photography in good light, and No. z for Dull Light and Interiors where the time required to match the standard tint in No. r would be too long.

PH0TOMICROGRAPH OF EGGS OF LOBSTER rvioTH.

l'vlagnified -1-0 diameters.

Special Sensitive Ortho. Plate, backed. A. E. Tonge.

r8

....

'D

~ _~

Special Sensitive Onbo., backed.

Exp. 3 secs., f/16, Dec. 26th, 9.45 a.m., dull. THAMES EMBANKMENT.

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W. E. Straw.

The price of either Meter or Reckoner is r/-, and the two Meters can be supplied bound together in leather covers for 2/6 in Great Britain. In other countries the cost will necessarily be a little higher.

The method of operating the two Meters is identically the same; the strength of the light is measured by a strip of sensitive paper exposed through a hole in a tinted circle. The time taken for the sensitive paper to darken to the standard tint is used to fix the exposures, and one movement only of a little slide indicates simultaneously the correct exposure for every stop. The sensitive paper is the same for both Meters, so that there need be no fear of mistakes.

The Exposure Reckoner is very similar in its method of working;

but instead of actually measuring the intensity of the light, a table of light-values for all periods of the year and all times of the day is given; from this the times of exposure are ascertained in the same ready manner as with the Meter. Every possible condition is taken into account, such as state of the weather, plate speed, stop, and seventeen different kinds of subject.

~:;.~\There is no calculation whatever in connection with these instruments; they ate simple, accurate, and above all helpful to every photographer who takes enough interest in his hobby to desire the best results.

•-PM0"4 ,~•,••TOP .. _,.T .. A

_ .. vlt~?

20

N.F. plate, backed.

Exp .. 1 sec., f/'d. Sept. WHITBY ABBEY.

2!

Frank Bolton.

IMPERIAL LIGHT-FILTERS .

SPECIALLY DESIGNED FOR USE WITH IMPERIAL ORTHOCHROME PLATES.

The use of a Light-Filter necessarily lengthens the time of exposure in proportion to the density of the tint. Imperial Light- Filters are made in three densities. These densities are expressed as x 2, x 4, x 8, meaning that when a screen is used the normal exposure is multiplied by two, four, or eight times, according to the density employed.

. For hand-camera work outdoors, and for all purposes where short exposures alone are possible, the "two-times" tint is suitable, as it only multiplies the normal time of exposure by two. The "four- times" tint is the one most commonly used, as it gives about the right amount of correction for landscape photography and general purposes; while, when used in bright weather in combination with that most rapid of all Orthochrome plates- Imperial Special Sensitive- snapshots are quite possible. For Flower Photography, copying, and other subjects where much colour contrast is included, the "eight-times" filter is recommended.

The filter may be fitted either on the front or back of the lens, as most convenient, but it should not be exposed more than necessary to strong sunlight.

22

Imperial Light-Filters are made in six sizes as follows For lens hoods having outside diameters between these limits:

No. 0 for -1~ in. to Ir\ in. diameter.

No.

ri

in. to r1'\r in.

No. IA r{-in. (see below) No. 2 1IJ-in. to Ii~ in.

No. ₃ Ii in. to

r}:J !n .

No. ₄ I"§-in. to

zt

^In.

No. IA is made specially to suit lenses, having a diameter of 1¼ in., fi.Lted with ^II Unicum" Shutters. The space between the lens hood and the shutter mechanism is limited, therefore this size Filter is not fitted with a spring. The inner diameter of No. IA is 1-5/16 in., and the user may have to line the Filter with a strip of paper to suit the exar,~ diameter of his lens.

Each size is made in three densities, representing normal expos11re multi- plied by two, four, and eight times. The density is engraved on each Filter, and is expressed as" EXP. x 2, x 41 or x 8."

Other sizes and densities can be made to order at slightly enhanced prices.

PRICES. Ord. Qual. Sup. Qua!.

Each Filter fitted in lined leather case ... .

5/-

7/6 Set of two Filters, same size but different

densities, in case ... . 9/6 14/6 Set of three Filters, same size but different

densities, incase ... . 13/6

21/-

When ordering state outside diameter of lens hood and density wanted.

BASHFUL CHUMS.

Special Rapid Orthocrome. Thos. Bletcher.

(No filter.)

Exp. r/20 sec., f/u. July. 5 p.m.

23

Press Opinions on IMPERIAL ORTHO. PLATES

"V./e are bound to admit that in the new 'N.F.' plate the degree of yellow sensitiveness imparted to the plate is raised to a point which we have never found before in a commercial plate. It would seem that this effect is produced by a screening action of a dye in the film itself, a self-contained light-filter which during development and fixation wasl1es out of the plate and leaves it clean and free from stain of any kind whatever. \Ve" ish to emphasize this point because we have come across dyed plates which required somewhat more than the ordinary treatment to rid them of colour.

There is a notable freedom from halation, a result apparently of the screening action of the dye in tbe plate.

'' The 'N .F.' plate is of such sensitiveness that snapshot exposures running to I-25th of a second at a lens aperture of //6 have gi,·en us well-exposed negati,·es of portrait subjects using the Imperial 'Pyro-Metol' developer.''

British ]01tr11al of Photog1'aphy.

"Amateurs will hardly need to be told what an immense step forward is being made when their ordinary every-day hand- camera snapshot negatives are made on Ortho. plates and with a yellow scree11, and so are capable of rendering as closely to truth as may be the more elusive tones in their subjects.

''Asa test we took a subjectincluclingcleep reel, strong yellow, differing shades of green, and deep blue, and the Imperial Ortbo- chrome plate stood the test well. The greens did not refuse to register in clue tone; the reel, which on an ordinary plate would barely, if at all, have affected the plate, gets a good half-tone, while the yellow is well brought out. Al I this is quite satisfactory.'' A matenr Photog-raphe,,.

"The Special Sensitive plate lem·es little to be desired. The characteristics of these fine plates appear to be remarkable-freedom from fog, fineness of grain, and latitude in exposure and develop- ment. A series of exposures of from r/,-₀ sec. to 2 secs. on a brightly lit seaside subject ga,·e, with suitable development, practically identical negatives. Exposures of ,ih, sec. and a five- times screen were easily possible at the seaside (in July)."

Photographic News.

"vVe do not know how it has been clone, but the Imperial Company has managed to get all the effect of the light yellow light-filter, in damping down the sensitiveness of the plate to blue and violet, without reducing the general speed in the way that with any light-filter is inevitable.

"The' N.F.' plates seem made to fit exactly a very important photographic requirement- that of a plate which will give a good colour rendering under all ordinary circumstances, yet which does not either in itself or its filter put band-camera and similar uses out of the question.

"There is nothing more to be said about it. It behaves in development as a plate should do, or as all Imperial plates do, which is the same thing in other words. "-Photographic News.

24

IMPERIAL · PAPERS.

IMPERIAL P.O.P.

(A superb printing-out-paper).

Made in Glossy Surface only.

In Four Tints-Mauve, Deep Mauve, White, Rose.

IMPERIAL BROMIDE PAPER.

Made in two surfaces-Platino-Matt-Rough.

Ditto Smooth.

IMPERIAL GASLIGHT PAPER.

Made in two surfaces-Platino-Matt-Rough.

Ditto Smooth.

IMPERIAL POSTCARDS.

P.O.P.-Mauve and Deep Mauve-Glossy Surface.

Bromide-Smooth.

Gaslight-Smooth.

IMPERIAL · PA PERS.

OTHER VARIETIES

OF

IMPERIAL PL4 TES

(Non-Orthochromatic).

IMPERIAL "

FLASHLIGHT" •

H. & D. Speed.

350-375 Pre-eminent in speed. Nothing faster made.

The

plate for high-speed shutter exposures

and

dull weather.

IMPERIAL "SPECIAL SENSITIVE" • The plate for professional photographers.

Great

rapidity.

Exquisite

gradation.

IMPERIAL " SPECIAL RAPID"

The most

popular

plate in

the

world

for

short exposures

in

Studio

and

Outdoors.

IMPERIAL "SOVEREIGN"

A high-speed plate

of delightful quality;

_

specially suitable for stand-camera work, and for hand-cameras

in

bright

weather.

IMPERIAL

."

ORDINARY"

Noted for fineness of grain and rich density.

250-275

200-225

150-175

80-lllO

IMPERIAL "FINE-GRAIN

ORDINARY"

40-50 For

copying or making enlarged negatives.

IMPERIAL

"LANDSCAPE "

IMPERIAL

"PROCESS" -

IMPERIAL

"SPRCIAL LANTERN"

-

30-40 10-15

5

IMPERIAL PLATES possess the qualities most

essential for successful holiday negatives.