Brian Pritchard

I believe that the Ektachrome stocks were always identified by plain language i.e. Ektachrome EF; Ektachrome Commercial and also Kodachrome. The colour neg stocks had a letter at the start of the footage number for example 5247 was identified with an F. The data sheets give the identification of each stock. I have a large number of data sheets and would have to read through them all to extract the information. Brian

Thanks for the comments. Unfortunately I only have a couple of frames, like many of the samples in my collection. I always keep a look out for anything unusual. Often it is only possible to quickly photograph them. If possible I like to make high quality scans. There is a short Gasparcolor film on my website which might interest you. Brian

The best route to take is to shoot the motion picture stock in your stills camera. The problem is finding a lab that will process the short lengths for you. This subject has been covered several time previously on this forum. Brian

This is a sample from my collection, I believe it is the Polychromide process. It was a duplex print one side toned magenta and auramine the other side with malachite green and helio safranin. Brian

Most of the 2 colour additive systems, as mentioned in my previous post, used red and green; however subtractive 2 color systems such as Dascolor and Cinecolor used Ferricyanide toning which is cyan coloured and an orange-red dyetoning. These were duplex systems with emulsion on both sides. Brian

Actually Freise-Green, Biocolor and Kinemacolor all used red and green rather than cyan. Brian

Just a point with Dufaycolor, the film had to be shot and projected through the base for the system to work. As well as reversal stock, Dufay also produced a negative and print stock. The Friese-Green material is held at the bfi/National Archive. He shot 22,000 ft on his trip from Land's End to John o'Groats. I did the original digital restoration of some of this material at The Digital Film Lab (when they had an office in London),it was for the then Curator of the Archive, David Pierce, to use in a lecture at the National Theatre, I was a consultant at the Archive at the time. I also made the filter wheel shown in the BBC programme. I have a picture of the machine made by Vinten for Friese-Green so that the positive prints could be coloured. You can see the picture on my website http://www.brianpritchard.com/Anorak%27s%20Corner.htm. The machine enabled 8 alternate frames to be coloured, say Green. You then wound on the film and coloured another 8 frames. When you had coloured the whole reel green you had to go back and colour the intermediate frames red. Brian

It has a silver anti-halation undercoat which needs to be bleached to be removed during processing. Brian

You can download an Eastman Kodak Booklet 'Photography of Colored Objects' dated 1919, from the Internet Archive. Although this booklet is concerned with still photograpic plates I am sure the information would apply to films. In the boklet it states that although orthochromatic plates are sensitive to green the sensitivity is 1/40 compared to the blue. It recomends the use of a yellow filter to reduce the sensitivity of the plate to blue. It also says that panchromatic plates have a much higher sensitivity to blue than to the green and red. The blue sensitivity is 7/8 and the green and red 1/16 each. Again it suggests the use of a yellow filter to balance the sensitivity. It would be interesting to know if movie cameramen used a yellow filter or accepted the lack of green sensitivity. Brian

Hello Bill I would recommend the book by Dr R W G Hunt 'The Reproduction of Colour' Fountain Press. You can get second-hand copies from $3.16 plus P&P from Abe books http://www.abebooks.com/servlet/SearchResults?an=R+W+G+Hunt&sts=t&tn=Reproduction+of+Colour&x=0&y=0 There have been a number of editions, if you are particularly interested in digital then you would need the latest edition which is around $160. Brian

This is the definition of Cirle of Confusion from the Ilford Manual of Photography. Lens Aperture and Depth of Field. If the focussing scale is set to give sharp focus at, say, 15 ft., then objects at 20 ft. and 10 ft. respectively will be less well defined, and objects at 25 ft. and 5 ft. respectively will probably be very much out of focus. There will, however, be a range around 15 ft. over which definition will be tolerably good. This range, known as depth of field, increases very markedly as the aperture of the lens is stopped down. Depth of field can only be quoted for a given degree of permissible unsharpness, and this is defined in terms of “circle of confusion.” Points of light in planes other than that which is sharply focussed are reproduced as circles which are cross-sections of the pencils of light coming to a focus either behind or in front of the sensitive surface. If these circles are small enough under the conditions of viewing to be considered as points, then subjects in the same plane will be rendered sufficiently sharply. ‘Ilford manual of Photography’ Edited by James Mitchell 4th Edition Published 1949 by Ilford Ltd and Henry Greenwood & Co Ltd I hope this helps Brian

This is the Kodak definition of Special Order: SPECIAL ORDER PRODUCTS Eastman Kodak Company provides a number of Special Order items that are used in special trade applications. These materials may be unique products derived from a parent product, product being test marketed, low volume products, products seeing diminished use, and similar considerations. These products may be listed as SO, O, MX, KIND, GRADE, or other generic designation. The listing of such a product in the catalog does not represent a commitment of continued availability by Eastman Kodak Company. Most of the Special Order Items are available in sizes or configurations other than shown here, however, there will generally be substantial minimum-order requirements. Their Motion Picture Catalogue lists the following SO products: SO-205 Vision 250D Estar Base SO-219 Vision 500T Estar Base SO-227 Colour Pos Leader SO-297 Test Leader Brian

SO stands for Special Order. It means that the stock has been produced to a special order because it does not appear in the catalogue. If you request a particular film with, for example, non-standard perforations - you might ask for Colour Negative stock with pos perfs it would have to be produced to Special Order. There would normally be a minimum order. Any stock that is not in the catalogue is given an SO number. If the stock has a large demand it will eventually be given a regular number and added to the catalogue - it might still have a large minimum order! The only way to find out what these films are is to ask Kodak. Brian

Dominic I am not sure that is what Casey meant. I read it as the lab had graded out his tobacco filter and he wanted to put it back by regrading the print. However I would agree that telling a grader what ights to use is not a great idea because if you make a mistake and the print comes out wrong you will have to pay for another print whereas if you requested a certain colour correction and the grader gets it wrong you should get a reprint - at least that is the way the labs I have a worked in resolved the problem Brian.

A printer point is 0.025 Log E and equivalent to a 2.5 CC filter. A 30 CC filter is equivalent to 12 points. If you are using filters to work out what correction you will need when printing you have to remember that because of the uplift in contrast between the negative and print, a smaller correction will be required on the negative to give a larger change on the print. Each change of a printer point will make a change of 0.07 density on the print (at the LAD density). So if your print requires a 30cc yellow correction, 0.3 density correction, then the correction to your negative grading would be 0.3/0.07 = 4.28, giving around 4 points. You would increase the blue light by 4 points and reduce the red and green by 2 points (if you want to keep the density the same). The other point to bear in mind is that when using filters to colour correct you have to judge by the middle tones because the filter will overcorrect the highlights and undercorrect the shadows. Brian

There is no reason why you can't specify printer lights. The normal set-up in a lab means that their lights remain constant. The trims on the printer are used to compensate for variations in light output, process variations and so on. It is vital for a lab to maintain their line-up otherwise a job that was graded 10 years ago would have to be re-graded if it needed to be printed today. This is the reason that the standard light will vary from 25-25-25 as new and different film stocks become available and depending when the lab standard was first set-up. Brian

There was a lot of discussion in 1930 in the SMPE Journals regarding projection aperture. There was an article in Jan 1930 by Lloyd Jones of Kodak entitled 'Rectangle Proportion in Composition'. The SMPE maintained that the aperture should be kept at 1.33 for sound on film prints. There is further information that says that many major studios in Hollywood used different projection apertures in their theatres. Later, in May 1930, the SMPE issued the following statement: "WHEREAS, Investigation has revealed wide variance in theater projection practices and that there is no effective standard aperture for projection of sound-on-film talking motion pictures; "Be it resolved: That as a temporary measure this committee recommends that all studios and cinematographers using sound-on-film methods make marks on the camera ground glass equally spaced from the top and bottom in addition to the mat mark for the sound track ; these marks to delineate a rectangle 0.620 by 0.835 inch in size and that all vital portions of the picture be composed within these limits; This gives a ratio of 1.35. In Feb 1932 the Standards Committee recommended an aperture of 0.590 x 0.825, a ratio of 1.4. In March 1932 the Standards Committee settled on an aperture size of 0.825 x 0.600 giving a ratio of 1.37. This was after a simultaneous study with the Academy of Motion Picture Arts and Sciences. There is no mention as to why they had finally settled on this size. Brian

To me it is an interesting query and I want to find the answer. I really don't understand your post ; it doesn't help or add to the discussion in any way. Brian

My investigations so far agree with Charles that this was imprinted by Kodak when processing Kodachrome. Brian

I recently, on another web forum, recommended Rocky Mountain for processing old Kodachrome but they were rather slated by other correspondents. Other places recommended were: http://www.filmrescue.com/ Pro 8 in Burbank I don't know or had experience of any of these companies (including Rocky Mountain) but thought I would mention it. Brian

The term 'Sharpness' is a recognised, scientific term used by Film Technologists throughout the world. It is not something invented by Kodak to sell films. There is an excellent article that can be downloaded from the Internet Archive by Higgins and Jones titled 'The Nature and Evaluation of the Sharpness of Photographic Images' It is in the Journal of the SMPTE Volume 58 April 1952 PP277-290. This is the Ilford Manual of Photography definition of Sharpness: Sharpness The appearance of the edges of well-resolved detail in a photograph is termed sharpness. When a film is exposed while partially shielded by a knife-edge, the image after development does not change abruptly at the knife-edge from a high density to clear film. Instead, there is a measurable density gradient across the boundary. One reason for this is the turbidity of the emulsion, which results in the diffusion of light beyond the knife-edge. Adjacency effects in develop- ment (page 431) may also affect the image at the boundary. The quantities acutance and contour sharpness have been defined in the U.S.A. and Germany respectively as expressions of sharpness in terms of this density gradient. Brian

You can't use ultrasonic splicers on acetate film - well you can but it burns the film and doesn't stick very well. You have to use cement splices. Brian

As I mentioned in my previous post, sharpness is defined and calculated by exposing a knife edge on the film and then measuring the black to white transition. If the film is 'sharp' then the transition will be 'sharp' if the film is less 'sharp' the the transition will be less 'sharp'. This has nothing to do with lenses or optics and is purely a function of the film emulsion along with all the physical factors of the film's construction and chemical effects of the processing. Brian

A quick glance through the Kodak glossary shows some very odd explanations - 'Grayscale - a black and white image' for example. The definitions for A and B wind stock do not specify whether you are looking at the emulsion or the base side so are no help whatsoever. Brian

The stock was 5305 known as IB blank, it was normal B/W release positive with an extra overcoat of gelatine to absorb the dyes. 3M's also made IB blank. One of the advantages of the process was that if anything went wrong in the dye transfer the blank could be washed off and re-transfered. At the take-off end of the processing machines the operator viewed the print coming through and had control of three water taps which allowed him to change the colour balance by altering the wash off of each dye. I spent a couple of days at the London Technicolor plant when I worked at Kodak. The batch of IB blank in use had over-exposed 'Kodak Safety Film' legend. There was no more stock in the country so we had to dip test every roll to check the edge print before the roll could be released for sound track printing. The process was running constantly so we worked very hard to prevent the process having to be shut down. Technicolor ran an IB plant in Hollywood in the 90's, I saw some of the reels from it; it was wonderful. We were able to compare to Eastmancolor prints. I believe the film was the remake of King Kong. I think that they made 100 copies by IB. Brian