Brian Pritchard

Using Sieves might help but you shouldn't leave them in the can as they will continue to dry the film out. Also if there is a lot of moisture around they will eventually become saturated which would defeat the object of using them. The FICA system for storing film archivally takes 2 weeks to acclimatise the film at the ideal humidity before sealing into bags and freezing them. Obviously more difficult with film that has to be kept in the dark. The most important thing is to allow the film plenty of time to warm up after freezing - at least a day before opening the sealed can. Brian

The SMPTE standard for short pitch in 35mm and 16mm was proposed in December 1952. It was proposed because of the introduction of low shrink film bases. Prior to that the negative shrunk during processing and allowed it to be continuously printed onto normally perforated print stock. Brian

Reliance the owners of ILab have closed the processing facility in Poland Street. You can read about it here: http://www.broadcastnow.co.uk/technology/reliance-calls-time-on-ilab/5035043.article Brian

Thank you for your kind remarks Charles. I believe that D76 was invented by Capstaff of the Eastman Kodak Research Labs in 1926, it was specifically designed as a motion picture developer but, of course, became used universally. I think that the use of yellow dyed films and a violet filter is not quite the same as the multigrade printing papers where the papers have two different emulsions that are sensitive to different colours, one being a low contrast emulsion and the other a higher contrast emulsion. Filters allow you to vary the contrast of the paper by varying the proportion of each emulsion. I presume that the violet filter holds back the exposure of the negative highlights more than the shadows and therefore reduces the contrast and also the maximum density. The original booklet has frame samples of nitrate film and although I took a lot of care scanning them it is not the same as looking at the actual films. Brian

I don't believe that it has any effect on contrast provided you give sufficient exposure to ensure that the blacks are black. You would not normally find it necessary to filter the light when exposing the dupe positive. The orange mask doesn't act like an orange filter on B/W negative because of the way that it is inversely proportional to the amount of dye present, if you had an area of deep blue in the colour negative there would be no mask present to hold back the colour. When an orange filter is used on a camera it is holding back the light reaching the film that it is not transmitting i.e mainly blues and blue greens, so they would appear light in the negative and dark in a print. You could use 5222 and then make the negative on dupe pos stock, that would bring the contrast back to the correct contrast. In the early days of the cinema (around 1927 onwards) there was only one duplicating stock that was used for the master pos and the dupe negative. They were both processed to a gamma of 1.0. Excuse the self promotion but you will find a transcript of the booklet 'Eastman Duplicating Film - its Properties and uses' from 1927 on my website here: http://www.brianpritchard.com/Eastman_Duplicating_Film_1927.htm Brian

If you are using 35mm you could use Orwo DP31 which is a panchromatic duplicating positive http://www.filmotec.de/?cat=24&lang=en&lang=en Their website says that it can be used for the very process we have been talking about. Unfortunately it is not available in 16mm. Brian

If it is Kodak Stock, you will find the information in the section on can labels here: http://www.kodak.com/US/plugins/acrobat/en/motion/education/Film_Basics.pdf Brian

The answer to your question is that the masking is filtered out during printing. The masks are there to correct for unwanted absorptions in the dyes. The couplers that produce the magenta and cyan dyes are coloured; the magenta coupler is coloured yellow and the cyan coupler is coloured magenta. Together they make the orange colour seen in a colour negative. The amount of coloured coupler visible is inversely proportional to the amount of dye present. If there is the maximum amount of dye present then there is no coloured coupler. If you have a highlight that is white, then there would be no dye and the maximum amount of coloured coupler. It is common practice in many labs that if you want to grade a black and white negative and then print it onto colour print stock you used a piece of unexposed, processed colour negative as a filter, firstly in the colour analyser and then in the printing machine. If you don’t do that then a large chunk of your correction goes in trying to get a neutral colour. With the film base filter your ‘normal’ exposure will lie somewhere in the middle of the light range of the printer. If you want to know a bit more about masking you can find some information on my website including some unique samples of single layers of colour negative with and without masks. http://www.brianpritchard.com/why_colour_negative_is_orange.htm Brian

Whoops, I should have said orthochromatic (sensitive to blue and green). Sorry Brian

Actually B/W positive stock is not orthochromatic (sensitive to green and red) it is as you say blue sensitive only. This means that you will only get a print of the yellow layer which happens to be the layer with the most grain. Many years ago Ilford use to make a panchromatic b/w print stock just for this purpose. I have attached some images made via Photoshop that will give you an approximation to what you would get. The first is an Eastman colour print, the second the equivalent of a panchromatic print and finally a blue sensitive print. Brian

You do need to be a bit careful in case the IR lamps are giving off any visible light. You could test a short length of a fast B/W stills neg by leaving it under the lamp for a few minutes with a coin placed over the middle of the film and then developing it to see if there is an image of the coin. This is the standard way to test a safelamp in a photographic darkroom. Brian

I think that you will find RP stands for 'rapid processing'; meaning it can be processed at high temperature. Brian

You can download the file here: http://www.4shared.com/file/NLBX-1mC/The_Small_Film_Unit_and_the_La.html Unfortunately you have to wait before the download starts and probably get adverts as well. If anyone can suggest a better method please let me know. Brian

Hello Tom I am sorry it has been a problem.. Unfortunately I have to use a free website server - I don't receive any money from my website. The free servers restrict the size of file that can be uploaded; the free file sharing website only allows a few seconds viewing. I think the only alternative at present is to allow people to download the video file. I will post a link so that the file can be downloaded. Brian

I have to say that the term 'double head' has always been used in the labs I worked in as well as by editors. Also 'married print' was nearly always used although the term 'combined print' was in use as well. The term 'approval print' is sometimes used in place of 'answer print' Brian

An answer print is the first print that is sent to the customer for him to check the grading. A married print is a print with a sound track (the sound is 'married' to the picture!) An interpositive is a low contrast colour positive with colour masking which is made from a camera negative as the first stage in duplicating. From the interpositive you make a duplicate negative. The same stock is used to make the interpositive and the duplicate negative; it is usually called colour intermediate stock to distinguish it from colour internegative stock which is used to make a duplicate negative from a normal or low contrast print or from a colour reversal master. Quite often a duplicate negative is called an internegative but most labs would save that term for a negative made from a print as described above. Brian

If you need the metric pitch: 35mm long pitch is 4.750 mm, short pitch is 4.740 mm and 16mm long pitch is 7.620 mm, short pitch is 7.605 mm. Brian

The masking is to correct for unwanted absorptions of the dyes and is produced by incorporating coloured couplers in the film. The cyan and magenta layers have coloured couplers; the yellow layer does not have a coloured coupler because yellow dyes have little unwanted absorption and there are not any suitable coloured couplers for the yellow dye. If you process unexposed negative film all you will see is the colour of the unused couplers (usually an orangeish colour), if you completely fog the negative and process it all you will see are the colours of the dyes albeit it will appear black. At other densities you see a mixture of dye and coloured coupler. Although the amount of coloured coupler is inversely proportional to the amount of dye formed it is a different colour to the dye so does not affect the measurement of the dye. If you have a single colour step wedge, for example magenta, the green density would rise as the exposure rises and the yellow density would fall as the exposure rises. The amount of magenta coupler present does not affect the green density. The masking is, as I mentioned, designed to correct for unwanted absorptions, if the film were not masked then the magenta layer for example, would control not only the green light but also the yellow light so that when you printed it instead of a pure green you would have blue added to it. Brian

The colours that any three colour RGB system can display is entirely determined by the dyes, phosphers or LEDs. If you plot the three dyes, phosphers or leds on a CIE diagram you get a triangular shape. The only colours that system will display are contained within the triangle. In the diagram attached some generic Kodak film colour dyes are shown. The horseshoe shape shows the pure spectrum colours. You cannot reproduce the pure spectrum colours using a three colour system. If the violet you want to record and display lies out side the colour triangle then you cannot reproduce it. This applies to film, monitors, inkjet printers and paper prints using three colours. Brian

All emulsions are sensitive to blue light; they are made sensitive to other colours by sensitising dyes. Colour negative has the blue sensitive layer on top, producing yellow dye, there is then a yellow filter layer to absorb the blue light then there is a green sensitive layer producing magenta dye and finally a red sensitive layer producing cyan dye. Colour print does not have a yellow filter layer, the layers are sensitised so that the green sensitive layer and the red sensitive layer have a low sensitivity to blue light. The order of the layers is green sensitive producing magenta dye, red sensitive producing cyan dye and at the bottom blue sensitive producing yellow dye. This order is used because the magenta dye contributes the most to visual sharpness whilst the yellow dye contributes the least, With this order you get the visually sharpest result on the screen. Brian

Here is a photo of a piece of acetate on the left and poly on the right seen through a pair of crossed polariser. Brian

There probably will be but it is something you don't need to worry about. If you are having a film print grading will take care of any shift and the same if you are going through a telecine where the colourist can make corrections. The only time when you really have to worry about colour shifts is if you are shooting still transparencies that are going to be projected, then you have to be sure that your colour balance is right as you don't have any chance to correct the colour. A greater concern is whether the film has lost speed due to poor storage. Brian

A non-destructive test is to look at the film sandwiched between cross polariaers. Acetate will be opaque whilst polyester will be transparent. Brian

Hello John They are owned by an Indian group Reliance. Their lab website is here: http://www.reliancemediaworks.com/Default.aspx Brian