US1460703A - John o - Google Patents

Description

J. G. CAPSTAFF July 3, 1923.

PHOTF GRAFHTI ZTVLRTA! EFDIi-JSS Filed March INVENT R JzhJz/fifdajnst ATTORNEYS.

BYQ X 7 "F1? @El i WITNESS Patented July 3, 1923.

UNITED STATES 1,460,703 PATENT, OFFICE.

JOHN G. CAPS'I'AFI', OF ROCHESTER, NEW YORK, ASSIGNOR TO EASTMAN KODAK COI- PANY, OI ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

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Application filed March 2, 1921.

To all whom it may concern.-

Be it known that I, Joan G. CAPSTAFF,

a citizen of the United States of America,

residing at Rochester, in the county of Monroe and State of New York, have invented certain new and useful Improvements in Photographic Reversal Processes, of which the following is a full, clear, and exact specification.

' My invention relates to the making of positive pictures upon the same support and in the same sensitive layer that is exposed in the camera, and more particularly is an improvement in the method known as reversal, in which a ne ative silver image is made by exposure and development, this silver image being removed from the undeveloped silver salts, which are then converted into a positive image.

One of the reat obstacles to the successful practice 0? this method is the necessity for such exact ex osure and development that there will be le t, after the removal of the developed ne tive silver image, an image in the undeve oped salt that reproduces correctly the tones of the ori 'nal subject. As it is generally expressed, t ere is no latitude in the exposure. Moreover, any slight inequalities in the emulsion or variations of the emulsion as a whole from the standard produce objectionably non -uniform positives.

I have perfected a process by which it is possible to allow as great latitude in the original exposure as is permissible in making ex osures for the production of negatives to used in the customary printing methods. I would mention as pre-eminentl important the controlled exposure to lig t of the sensitive silver salts remaining after the removal of the developed negative silver image, in a step analagous to the printing of a positive from a negative. This will be more fully described hereinafter, with many other new steps and refinements in the pro ssible the production of 05- itives of uniform quality, all o-f-whic I. nvention, as more pre-' be obscured. I will then describe fully and Serial N0. 9,249.

precisely the exact formulae and materials used in my referred process and indicate what precautions and care are necessary, and to what extent the ste s may be varied and equivalents introduce Following this, I will make some general remarks pertinent to the process as a whole.

While this process is of general application, it has been developed particularly with a view to use in the making of motion picture positives upon the film exposed in the camer a, and I will describe the preferred process as applied to a strip of motion picture film embodying a long band consisting of a support 0 a cellulose ester composi tion coated with a silver emulsion.

It is to be understood that the process as completely given below is illustrative and that I do not limit myself to the details thereof. These are iven with a considerable degree of particularity in order that others ma know full the methods which I prefer-ab y follow. ther equivalent steps bromide gelatine .and formulas may be used, and the features of novelty which I describe and claim may be introduced into processes differing considerably from those here given.

Referring to the accompanying drawing: Fig. 1 illustrates schematically the means used for determining the characteristics of the film, and

Fig. 2 illustrates the arrangement of the room in which the printing is done.

The steps of the complete preferred process are as follows:

1. Expose'in the camera.

2. Develop, resulting in a silver negative image in a sensitized layer.

3. Wash.

4. Reverse, i. e., remove the silver image.

5. Wash.

6. Clear in a bisulfite bath, removing products formed in step 4.

inse.

8. Ascertain characteristics of 9, Bathe in'an alkali bath.

10. Rinse.

11. Expose to a controlled printing light.

12. Develop. 13. Rinse. 14. Fix in an acid-hypo bath, removing undeveloped silver salts.

15. Wash and dr I will now descri the steps fully.

the film.

The exposure, moreover,

1. The exposure is made in the camera in the usual way. In all photographic processes there is a certain permissible variation in exposure consistent with the obtaining of the best results, and a further variation permitting passable or printable results. In reversal processes this latitude of exposure is extremely small and, exposures must be very exact to obtain at all satisfactory results. In ordinary photog'gaphic processes, particularly with the ma rials and rocesses such as aroused in ordinary and camera work, this latitude is very great. While it is desirable with my process as with any other photographic process that this exposure be carefull timed, itis possible to vary it in substan ially the same degree as in ordinary amateur hand camera work. is made directly on the emulsion surface and not through the support as is necessary in many reversal processes.

2. The developer used should be a contrasty one, by which I mean one producing in the silver negative image a high degree of contrast or high gamma as it is denoted in photographic literature; and the development should be continued until all-exposed grains have been developed, or to gamma infinity as it is denoted in photographic literature. If only partial development is given, the contrasts will be incorrectly renered.

I first take the following developer:

A. Sodium bisulphite -Q. 25 gms. Hydr uinone 25 gms. Potassium bromide 25 gms. Water to 1 liter. B.

Sodium hydroxide 50 gms. Water, to 1 liter.

this being a known process developer. The following formulae is then made up.

A+B, equal parts 3 liters. Sodium thiosulfate (30% solution) 25 c. c. Formalin 10-30 c. c.

10 minutes in running water is necessary and suflicient.

4. The film is now submitted to a reversing bath, preferably the following:

Potassium permanganate (4% so lution) 1 part. Sulphuric acid (20%) 1 part. Water Q0 parts.

It is understood that if a long strip of motion picture film is being treated it will be wound on a drum or reel prior to development and kept thereon through all the steps. During this reversing process this reel is rapidly rotated, or the sensitive element is kept in vigorous motion by other means, as otherwise a heavy deposit, presumably of manganese dioxide, collects in the form of a metallic lustre on the surface of the film and has a stron tanning efiect on the gelatine which retar s the dissolving of the negative image. The bleaching or reversing is continued untilthe silver has been entirely dissolved or removed from the sensitive layer, leaving onl the unexposed and undeveloped silver sa ts. Other oxidizing baths such as acid bichromate or any bath that dissolves out the silver leavin ithe silver halide salts, may be used. These aths should not, however, contain any soluble salts capable of forming insoluble silver compounds, as by reaction with the silver sulphate, as these would prove objectionable in the later steps of the process. The undeveloped salts are rendered insensitive by the presence of the oxidizing bath and by manganese dioxide Or other products; and any latent image on the salts is destroyed so that the element may be exposed to white light before and during this bath without damage.

5. The element is then washed.

6. It is then submitted to a clearing bath of sodium or potassium bisulfite or to any other bath capable of removing from the film the manganese compounds or any other roducts that may have been formed in the leaching operation. I customarily use a 1 to 2% aqueous solution of sodium bisulfite to which I submit the sensitive element for about five minutes. This restores to the undeveloped silver salts, at least in part, their sensitiveness which had been lost by the presence of the manganese dioxide or other roducts of the bleaching or reversin ath. It is desirable for uniform'res ts that a standard bath at standard temperature be used. I have at this step a sensitive emulsion from which the silver image has been removed. On examination this appears as a more or less translucent layer in which Exposure.

from the reel. A sketch of such a room R is shown in Fig. 2 the film F being wound on a reel or drum 15, supported by trunnions T resting in seats L in the standards M, and having a handle H by which it me be rotated. The lam s E are in the box with a difl'using from 6, and are controlled with an electric switch I, by which current flrom a suitable source, not indicated, is app; ied to the wires K. Any suitable chronometer C may be used by the operator for timing the A dark room lamp N with a screen transmltting non-actinic rays is also ill) shown. The duration of the exposure to the standard light is determined by the test already described. I use a light that will print average exposures satisfactorily in about a minute, errnitting the reel to be revolved many times and givin uniform ex osure throughout its length. he standar izing of any particular measuring means with the printing light used is, of course, to be determined by the operator by trial with the lighting conditions of his workroom. The exposure may be made of constant duration and the light intensity varied as by the rheostat X.

If the film should get accidentally overexposed or light struck at this time it can be de-sensitized and resensitized before redevelopment by resubmission to the reversing bath (step 4) and the clearing bath, (step 6), and again printed.

12. The sensitive element is now developed in safe light in any desired developer, and I find that a very wide range of developers may be used with satisfactory results. Having determined the contrast in the test strip already taken, it is possible that by appropriate choice and use of developer to modify the contrast of the finished pictures. For general use I find the following typical developer satisfactory:

Monomethyl aramido henol sulfate 23 s.

E P gm Sodium su lp ite 500 gms. Hydroquinone 92 gms. Sodium carbonate 50 gms. Potassium bromide 10 gms. Water 10 liters.

ing image may be controlled in a manner that is known to any practical photo pher.

In reversal processes such as I ve already referred to in which the exposure to light iscoincident with the redevelopment, the exposure may be controlled in similar While it is simplest to perform all the steps in succession on the film or other sensitive element, without drying between the ste s, it is possible to perform the steps at di erent times, drying the element between the steps. While I have described the use of motion picture film more particularly it is, of course, to be understood that other forms of sensitive elements may be used, and that I do not limit myself to any one form of support or emulsion. All of the operations are carried out at ordinary room temperatures, that is, from 60 to 70 F., except where I have particularly mentioned a temperature used to give a standard result, and in the presence of safe li ht only, except where otherwise'noted. ly standard practice, however, is to have all baths at 65 thereby insuring uniformity of working conditions and results.

The theories underlying this process are obscure, and I advance no explanation with confidence. It may be that even after the clearing bath there are left in the sensitive layer small amounts of manganese dioxide or other product of the reversing bath that have a destructive efl'ect on the latent image and these are distributed in that layer proportionally or difierentiall according to the original silver image. hen the second controlled exposure is made this may effect the latent image morestrongly at oints corresponding to the high li hts in t e positive since there are more of t e destructive salts at these points. Hence the contrast is greater if the second exposure is not too long.

nother possible theory is that the sensitive particles vary in sensitiveness that the most sensitive are first alfected and the less sensitive unafiected. The high 11 hts would thus cause the development of the most sensitive particles, while in the shadow fortions of the image, many of these would be unaffected. The second printing would then consist of the affecting by light of salts differentially sensitive in accordance with the orilgmal subject.

do know, however, that a controlled second exposure after a standardized clearing bath enables me to control the second printing in a manner comparable to the printing of an ordinary positive from an ordinary ne ative.

he theory of the action of the alkaline bath in preventing a second reversal in the redeveloping bath is also obscure and 1 advance no theory as to its action.

A field of usefulness for which this process is peculiarly adapted is the making of motion pictures by amateurs for home use. The great deterrent hitherto has been the exnse incidental to the purchase of both positive and negative films. Since the process I have outlined would probably and preferably be performed by a finisher under standardized working conditions, it makes it possible for the amateur to purchase the film, and expose it with the same order of care now necessary for satisfactory results with a hand camera, and have the film treated and reversed by a finisher, without the expense of paying 'for a second film. For home use the film and picture area may be much smaller than standard commercial film and a camera and projector of simpler design and smaller than the commercial ones may also be used, thus bringing the whole field to a point where the original outlay and the running expense will be comarable with that incidental to the use of a hand camera of ood quality.

The process a ove outlined may be used for the making of a positive from a positive, a sensitive element being ex osed either by contact or projection to lig t from or through the transparency or positive image to be co ied, and the steps herein described for making an original ositive followed.

Having thus describe my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a process of making photographic images b reversal from a photographic light sensitive element, containing an image, the steps of submitting the element to a printing light controlled in accordance with the rinting value of the element, and then deve oping an image in said element.

2. In a process of makin photographic positive images by reversa from photographic ne ative images in a light sensitive element, w ich process comprises the rendering of the negative image inert and differentially transparent and then developing the sensitive element, the step after such renderin and prior to developing of mittlin t e element to a printing ight trol e 3. In a process of making photographic images by reversal from photographic images in a light sensitive element, the steps of measuring the rinting and developing characteristics of the element and then submitting the element to printing and desub- in accordance with the printing- .value of the element.

veloping operations in accordance with the characteristics ascertained.

4. The process of making photographic positive images by reversal from photographic negative silver images in an emulsion containing light sensitive salts and comprising the following steps: the removal of the silver from the emulsion; determining the printing and developing characteristics of the emulsion; submitting it to printing and developing operations controlled in accordance with such ascertained characteristics and removing the undeveloped salts.

5. In a process of making photographic positive images by reversal from photographic negative silver images in a light sensitive element, which process comprises the removal of the silver from the element and the development of the element, the steps after such removal and prior to such development of measuring the printing value of the element and submitting it to a printing light controlled in accordance with the printing value.

6. In a process of making images by reversal from photographic images in a strip of sensitized film, the steps of submitting a series of test portions only of such film to a series of standard printing lights and treating such test portions to ascertain the printing characteristics of the film, submitting the film to a printing light controlled in accordance with the characteristics thus ascertained, and then developing the film.

7. In a process of making positive images in a strip of motion picture film having a sensitive emulsion, in which are inert and transparent photographic images, the steps of submittin test portions only of such film to a standar printin light behind a series of graded density tab ets, treating such test portions to ascertain the printmg characteristics of the film, submitting the film to a printing light controlled in accordance with the characteristics thus ascertained and developing the film.

8. In a process of making positive images in a strip of motion picture film having a. gelatine emulsion containing light sensitive salts and in which are inert and transparent photographic images, the steps of submitting test portions only of such film to a standard printing light behind a series of graded density tablets, developing such test portions to ascertain the printing and developing characteristics of said film, submitting the film to a printing light controlled in accordance with the characteristics thus ascertained, developing the exposed sensitive salts in accordance with the ascertained characteristics and removing the undeveloped sensitive salts.

9. In a process of making photographic images by reversal from photographic to an alkaline images in a light sensitive element, which process comprises redevelopment of the sensitive element, the etc of submitting the element to an alkaline ath prior to redevelopment.

10. In a process of making photographic positives by reversal from an emulsion containing light sensltive salts and a negative ima e, which process com rises the removal of t e negative image an the development of the light sensitive salts, the steps of submitting the emulsion after the removal and prior to the development to an alkaline bath. 11. In a process of makin photographic images by reversal from a ge atine emulsion containing light sensitive salts and a silver image, which process comprises the removal of the silver image, the exposure of the emulsion to light and the development of the sensitive salts, the step of submitting the emulsion to an alkaline bath after the removal and prior to develo ment.

12. In a process of making photographic positives by reversal from a gelatine emulsion containing light sensitive salts and a silver ima e which process comprises the removal 0 the silver image 1n an oxidizing bath, the clearing of the emulsion by the removal of the products of oxidation, and the redevelopment of the light sensitive salts, the step after clearing and before redeveloping of submitting the emulsion to an alkaline bath.

13. In a. process of making photographic images by reversal from an emulsion containlng light sensitive salts and a photographic image, which process comprises the removal of the image in a bath leaving objectionable products, the removal of such objectional products, the ex osure to light of the emulsion, and its re evelopment, the step of submitting the emulsion to an alkaline bath after the removal of the objectionable products and prior to development.

14. The method of treating a light sensitive element in which there has been formed an inert transparent image which consists in, submitting the element to an alkaline bath, and to a developing bath.

15. The method of treating a light sensitive emulsion in which there is an inert transparent image which consists in submitting the emulsion to an alkaline bath, exposing it to light, and then submitting it to a developing bath.

16. The method of treating a gelatine emulsion containing light sensitive salts and an inert transparent, photographic image which consists in submitting the emulsion bath, exposing it to a con trolled printing light in accordance with its printing characteristics, and then submitting it to a developin bath.

17. The method 0 treating a gelatine lightsensitive silver salts and an inert, transparent photographic ima e which consists in submitting the emu sion to an alkaline bath, ascertaining its printing characteristics, exposing it to a printing light controlled in accordance with the printing characteristics, developing the sensitive salts thus exposed, and removing the undeveloped sensitive salts.

18. The method of treating an element containing light sensitive salts and an inart, transparent photographic image which consists in submitting the element to an alkaline bath, ascertaining its printing and developin characteristics, exposi a printing ight controlled in accord nce with the characteristics, developing the exposed sensitive salts in accordance with the characteristics, and removing the undeveloped ts. 19. A photogralphic reversal process consisting o the to owing steps: the formation in a light sensitive element of a silver photographic ima dissolving out the silver ima e in an oxidizing bath; clearin the protfiicts of oxidation from the sensitive element; submitting the element to an alkaline bath; measuring the printin characteristics of the element; exposing t e element to a controlled printin light in accordance with such characteristics and developin an ima e in such element.

20. he metho of making a hoto raphic positive image consisting of t e f0 lowin steps: exposing to the controlled action 0 light a gelatine emulsion containing a light sensitive salt; developing a silver image to a high degree of contrast in the emulsion; dissolving out the silver image by an oxi dizing bath; clearing the products of oxidation from the sensitive emulsion; submitting the emulsion to an alkaline bath; measuring the rinting characteristics of the emulsion; su mitting the emulsion to a controlled printing light in accordance with such characteristics; developing the salts affected by the light also in accordance with such characteristics; and removing any undeveloped salts still in the element. I 21. The method of treating a light sensitive element in which there is an inert transparent image which consists in testing such element to determine its characteristics as to re-reversal, submitting it to an alkaline bath if it shows a tendency tolwail'ld re-reversal and then to a developing at 22. In a process for making photographic images by reversal from photographic ima s in a light sensitive element, the step 0 testing the element to determine its characteristics as to its tendency toward rereversal and as to its printing value and submitting it to suitable chemical treatment to overcome a tendency to reversal, if any,

emulsion containing and to a controlled printing light in accordance with the results of such steps.

23. In a process for making photographic images by reversal from photographic images in a light sensitive element, the step of testing the element to determine its printing value and its tendency toward rereversal, submitting it to an alkaline bath, if it shows a tendency toward re-reversal, submitting it to a printing light controlled in accordance with the printing value and developing said element.

24. In a process for making photographic images by reversal from photographic images in a light sensitive element, the step of testing the element to determine its characteristics regarding re-reversal and development, submitting it to an alkaline bath if it shows a tendency toward re-reversal and developing it in accordance with the results of such test.

25. In a process for making photographic images by reversal from photographic images in a light sensitive element. the step of testing the element to determine its characteristics relating to its tendencv toward re-ieversal, printing value'and contrast and subjecting it to suitable chemical treatment to overcome a tendency to reversal, if any, controlled printing and controlled development in accordance with the results of such steps.

26. In a process for making photographic images by reversal from photographic images in a light sensitive emulsion. the step of testing the emulsion to determine its characteristics relating to its tendency toward re-reversal, printing value and contrast, submitting it to an alkaline bath if it shows a tendency toward re-reversal, and to controlled printing light and development in accordance with the results of such steps.

27. In a process for making photographic images by reversal from a gelatine emulsion containing light sensitive salts and a silver photographic image. the steps of removing the silver image, submitting the emulsion to a clearing batln testing the emulsion to ascertain its characteristics as to its tendency toward rereversal. printing value and contrast submitting it to an alkaline bath if it shows a tendency toward re-reversal. submitting it to a printing light controlled in accordance with the printing value, developing the light affected salts, and removim the undeveloped salts.

Signed at ochester. New York, this 24th day of February. 1921.

JOHN G. CAPSTAFF.

Certificate of Correction.

It is hereby certified that in Letters Patent No. 1.460,?03. granted July 3. 1923, upon the application of John G. Capstaff, of Rochester. New York. for an improvement in Photographic Reversal Provessvs." errors appear in the printed specification requiring mrrection as follows: Page 4. lime 7. for tho \vul'd from read front; same page, line 40, strike out the word that :emi line 53 [or the word proportion read proportions; and that the said Li'llvl's Patent should he read with these corrections therein that the same may ronfm'm m the reomd of the case in the Patent Ofliee Signed and sealed this 31st day of July, A. D.. 1923.

[BELL] KARL FESNING.

Acting Commissioner of Patents.

Images