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Brian Pritchard

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Posts posted by Brian Pritchard

  1. The masks come from coloured couplers in two of the layers. The coupler that produces the cyan dye is coloured magenta and the layer that produces the magenta dye is coloured yellow. Together they make the orange colour. The layer that produces the yellow dye is colourless. The masks correct for unwanted transmissions in the dyes. There isn't an appropriately coloure coupler for the yellow dye and also the yellow dye does not have any great unwanted absorptions.

    If you are interested I have a page on my website with some film samples that show the individual layers with and without masking.

    http://www.brianpritchard.com/why_colour_negative_is_orange.htm

    These pictures were made at the Kodak research laboratory in Harrow on specially coated samples as there ia no other way to see the individual layers.

     

    Brian

  2. Dirk is quite right, of course. You can't make a CRI from an Ektachrome original. You have to make an 'normal' internegative. However if you are looking at a negative it will be masked and you wouldn't be able to see that the blacks are green without using a video analyser, the black areas would be white in the negative. Again it wasn't normal to make 35mm Ektachrome dupes. Would it be possible to post a frame scan so we can see what you are looking at?

     

    Brian

  3. Richard

    You must make sure that the film break rollers are held up into position, you usually do this by putting rubber bands to the roller above. The machine shuts down if the film breaks. You can only operate the trims manually. They move the 1 to 50 by 22 points. Only the light valves will work from the RF cue detector or the notch detector. It is possible that the other cables are FCC information from the motor. What you really need is the Model C manual. I am not sure when I will be in a lab next but when I am I will check for you if you can wait.

    Best Wishes

    Brian

  4. The BFI/National Archive don't do work for outside customers but, of course, this might change in the future. They do have the capability to do 16mm B/W work. Film and Photo can do A&B roll printing in both 16mm and 35mm. They use Schmitzer Model C printers and can do grading. I work there occasionally and recently graded some A&B's to make interpos's for them.

    I understood that Nowhere had a 16mm Debrie printer that people are able to use but that information might be out of date.

    Prestech run a fairly complete service in B/W and colour in 16mm and 35mm. Their main work is Archival preservation work but also do other work. They also have a very comprehensive digital setup including scanners and recorders.

    Brian

  5. The problem is really a financial one. Most labs have processing machines that use perhaps 1000L of develope,r if it is quite a fast machine. They would have to dump or store the current developer and then make up the new chemicals. Incidentally D76 is very similar to D96 the normal MP developer. Whilst they are processing your film they would not be able to process anything else. In addition they would have to run tests to establish running speed to get the required gamma on the stock(s) you are using. You would have to pay for the new chemicals, and if they had to dump the original bath you would have to pay for a new bath and probably the time involved for the technicians to do the work. Actually no lab is really happy with putting a new unseasoned bath in a machine; your special developer would probably stop them processing for a week.

     

    Brian

  6. The calculation is based on the molecular weight of the chemical: Sodium carbonate is Na2Co3 which has a molecular weight of (2 X 23) + 12 + (3 x 16) = 106 Water is H2O which has a molecular weight of (2 X 1) +16 = 18. So decahydrate has a molecular weight of 106 + (10 X 18) = 286. The molecular weight of monohydrate is 106 + 18 = 124. The equivalent weight of decahydrate to monohydrate is 286/124 so you would need 52.5 x 286/124 gms of decahydrate = 121 gms.

     

    I have a formula that uses anhydrous Sodium Carbonate the amount is 45 gms. So using the above calculation monohydrate would need 45 X 124/106 = 52.6 gms which is what you have quoted.

     

    I hope this is clear.

    Brian

  7. We came to FPD once (only once) for some cheap rushes when I was at LCP and they were rather pink!

    Went straight back to Filmatic after that, and hang the expense. They may have been one-light but it was a very good light. That was probably you then, 1980-82.

    I left Filmatic in 1981 to become Technical Director at Humphries. I will assume the excellent quality was entirely down to me! :D

    Brian

  8. Hello John

    Yes they are still in business. They work with a very small staff; I go in occasionally to help with grading and sensitometry.

     

    Brian

    Are they actually still in business then Brian ?

    Their website hasn't changed for ages, their price list is 2 years old and their 'items for sale' page is 8 years old.

     

    I emailed them about a year ago and never got a reply so assumed they'd shut down.

     

    John S :(

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