Brian Pritchard

We seem to be going over the same ground again and again. There have been two threads on the Film Processing forum already. ILab can only process colour neg. Film & Photo can process colour neg, E6 and B/W. They can also do 16mm prints in colour and B/W. Brian

Film and Photo have the capacity, I believe that although Prestech are able to print both B/W and Colour in 16mm they tend to prefer to concentrate on 35mm restoration. Brian

It is not correct to say that Soho is the last lab to print 16mm. Film and Photo print 16mm, both B/W and Colour, Prestech also are able to print both B/W and Colour and No.Where can print 16mm B/W. Brian

Thanks for all the clarification. Actually Film and Photo still offer a 16mm printing service in both B/W and Colour as well as colour neg and E6 processiing. Brian

I understand that Soho Images, who have been taken over by Deluxe, are stopping all 16 mm services and stopping all printing. I heard this second-hand (or should I say previously owned :rolleyes: ) so I hope it is accurate. Brian

Pity he can't get his facts right. Dwaynes has NOT closed: http://www.dwaynesphoto.com/ they have just stopped processing Kodachrome. They still offer C41, E6 and B/W. Brian

There is an interesting article in the SMPE Journal (Available from the Internet Archive) in Volume 14 (1930) page 108 entitled 'Camera and Projector Apertures in Relation to Sound-on-Film Pictures' by Lester Cowan. There was a lot of argument at the time regarding 'correct' picture ratios. Some argued that the rato should be kept at 4:3 for both silent and sound pictures with much discussion about 'golden cut' a ratio of 8:5. It also seems that all the Hollywood studios used different aperture sizes in their cameras, see Table 2 in the article. Brian

Alex The use of filters for re-grading is really only an approximation. As I mentioned in a previous post the filter will over correct on the highlights and under correct the shadows so it requires a lot of experience to decide on the correct filtration. The filters are most useful to decide whether the correction is blue, cyan or a combination of both, again for example. You also have the difficulty that printer points are discrete amounts; you can't correct by half a point, for example. If you are re-grading using filters you would look at the print over a light box, use the filters to get the approximate correction and then use your experience to judge whether a four point correction suggested by filters is really perhaps 3 or 5 points. This is the reason that the introduction of Video Colour Analysers in the late 60's was such a revolution for colour grading. Up to that point the first and possibly the second print ended up in the bin (or the bulk release if you were a little bit sharp) after the introduction the best graders were able to show the client the first print as the answer print. Before analysers some labs used special printers that were able to print a few frames of each scene at different lights to enble the grader 5o get a reasonable first print without the expense of printing a complete test print first. They were called scene testers; they were also used in the BW days. Brian

Thanks for that, I didn't think of looking on Ebay. Quite pricey considering you can't get it processed as colour. Brian

Does anyone have a roll (any length) of Ektachrome Commercial 7252, exposed or unexposed but unprocessed, that they don't want? I will, of course, pay any postage. Thanks Brian

I believe that reversal emulsions are thicker than negative emulsions. I suppose it depends whether your 7231 was put through as 'normal' reversal film or received a different development time. If your film has a high fog level then it probably didn't have sufficient development. 7231 is notorious for being difficult to dry so if the drying time is not sufficient you can get the film winding up wet or damp which will give you ferrotyping - shiny patches on your film. Drying marks indicate that the film was not squeegeed correctly before drying. These would be circular marks on the film. Brian

The amount of silver in the film won't affect the base fog when reversal processing. The high fog indicates that the first developer was insufficient. If the correct d max is not reached in the highlight areas then it leaves silver halide that can be re-developed in the second developer producing a high fog level. Insufficient bleaching will also increase the fog level. Brian

Did you remove the rem-jet backing? If not that is why the base looks so dark. Brian

I know of someone who regularly processes Agfa CP30 as black and white, I would have to check what gamma he gets but Agfa did some tests and made recommendations for processing through a normal B/W pos developer. Brian.

Marc You do it after the film is processed. It is to remove spots of backing that has got onto the emulsion. You can use silver wadding cleaner (called Duraglit in the UK) or cotton wool with liquid silver cleaner. Afterwards you must rewash the film to remove the tiny abrasions you have made. Backing left on the base side can be removed with cotton wool soaked in Perklone. Brian

I agree with Dominic's comments, however I would add that it is possible to remove backing from the emulsion. You have to carefully polish the emulsion with silver polish and then rewash the negative. It is very time comsuming and you have to take great care not to damage the film in any other way. I spent a morning earlier in the week doing exactly this. (not damaging neg but removing backing!) It is really only practical with occasional spots. Brian

I meant to say in my last reply that the SMPTE book, 'Control Techniques in Film Processing' gives all the information you need about control techniques. I have two SMPTE books, the one I mentioned which deals only with B/W and 'Principles of Color Sensitometry' for colour. I believe that the first book is out of print but you might find a second-hand copy. Brian

Alexandra You will need a step wedge to attach to your positive film. I presume you have access to a densitometer. Depending how quickly you need a wedge, if you contact me off-list I can send you one next time I visit the lab I work at occasionally. Brian

Hi Alexandra Unfortunately there is no way of knowing what the gamma of an old B/W Positive. You have to assume that it has a normal gamma of around 2.4 to 2.6. A dupe negative is normally processed to a gamma of 0.73 because it is designed to be printed from a duplicating positive which should have a gamma of 1.4. This gives a reproduction gamma of 1.0 which will give you a duplicate negative that is a close reproduction of the original negative. If you are making a duplicate negative from a print with a gamma of 2.4 then the duplicate negative should be processed to a gamma of around 0.4. Most labs I have worked in actually made negatives from positives at a gamma of 0.45. Duplicate negatives are always denser than original negatives as they are printed on the straight line portion of the curve. Brian

I believe that you should be calculating Overall Contrast for B/W negatives. Average Gradient is used for colour negatives. Overall contrast is the slope of the straight line portion between density point 0.10 above minimium density and the point corresponding to Log E1.50 of the exposure scale. If you are using a step wedge with 0.15 increments then that is 10 steps up the curve. If you are push processing you need to calculate the change in speed. It is not usual to measure push processing by change of contrast. The curve should move two steps to the left (if you are using a 0.15 step wedge). To be strictly accurate you should calculate the Exposure Rating : 100(1-Log E) where E is representing the exposure at a point of the density curve 0.20 above the D Min. It would be sufficient to see how far this point has moved to calculate the change in speed. The contrast you get will depend on the particular developer mix the lab is using. Brian

Thanks for the reply. Yes, maybe I have to put it on youtube. The problem maybe with the free internet provider I use. Brian

It seems to be playing OK on Opera and Internet Explorer but I couldn't get it to play on Firefox. I will keep trying to sort it out. Sorry. Brian

Sorry about the difficulties I will check to see what the problem is; I have just used Opera and that seems to be working OK, I will try Firefox and Internet Explorer. Brian

For those of you interested in film labs and processing I have a 16mm film made in the 70s streaming on my web site. The film is not quite of Academy Award standard! However it does have some interest. It was made by Humphries Film Labs and is called 'The Small Film Unit and the Labs' You will find it here: http://www.brianpritchard.com/British%20Labs.htm Humphries Film Labs was around from about 1927 until 1984 when it was closed down; I was technical director at the time, The lab also owned satellite labs in Manchester, Leeds and Glasgow. The Leeds lab eventually became Film Lab North and finally closed earlier this year. I hope one or two of you will find it of interest. Until recently only the first 7 minutes was available on my site due to using a free file sharing site. I have now converted it to flash and the full film is available. Brian

Another lab gives up film processing. http://www.nytimes.com/2010/08/14/movies/14arts-ATDUARTANEND_BRF.html At DuArt, an End to Film Processing By PATRICIA COHEN; Compiled by RANDY KENNEDY Published: August 13, 2010 Al Young, a film editor, and his partner, Arthur Gottlieb, started the DuArt film laboratory in 1922, during the era of silent movies. Now, after 88 years, Young’s son Irwin has announced that the company will process its last roll of film this month. “I grew up with film, so I’m sad to see it go,” Irwin Young, chairman of DuArt Film & Video, said in a statement. “But most of our clients have moved to digital image acquisition, and we’re moving with them.” The president of DuArt, Bob Smith, said the company was responsible for one of the first continuous-processing machines in 1927 and the first processing of Eastman Color negatives in 1951. The lab received an Academy Award for technical achievement in 1979 for the development of a frame-cueing system. Closing the processing lab, Mr. Young said, will enable the company to expand its digital work. Brian