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Home made contact printer


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#1 Nick Mulder

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Posted 28 March 2007 - 11:42 PM

After having heard a bunch of stock I just bought would be good print stock and taking a look around my room I realised I may have a quick and nasty contact printer already here -

How bout this for a possible quick hack:


1 x moviola synchronizer
1 x LED
1 x bunch of electronic gizmo's sensors and general circuit busybody stuff - glue, hypodermics etc...
1 x darkroom and collection of cinefoil offcuts


Run sandwhiched neg and print stock emulsion to emulsion film through moviola which is sensored to trigger a masked LED for a certain duration on each frame ...

Smart ?

yes yes - no no ?

hmmm - actually wouldn't that make an upside down print ? maybe its base to emulsion then and just make sure the LED light is as near to collimated as possible...

I have never seen a printer - no idea how they work, apart from knowing they use some liquid (water?) to make the stock and neg stick better-er ??
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#2 Joseph Winchester

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Posted 29 March 2007 - 01:23 AM

Hmm. It is an interesting idea. I have, in the past, looked at my magnasync moviola and imagined 2 layers of film running through it to print titles or make copies, but never went any further. It seems it could possibly work, although without any color controls... i guess black and white is all you'd be able to accurately print unless there's some sort of filter system. One of my photo enlargers, an omega d5500, has a pretty cool color correction system that uses 3 sliding color plates to mix cyan magenta and yellow to your liking. If you have the parts and the inclination, it might be worth trying.
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#3 Nick Mulder

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Posted 29 March 2007 - 01:32 AM

Sorry - yes, should have mentioned that... B+W only, for now

I might get to work one day soon - really its just the LED sensor thingy I need to make so that I can wind it through at any speed I want (as long as the rate isn't faster than the exposure time)

I should also think about what I'm going to do with it if it works! I'm so used to developing reversal...
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#4 Dominic Case

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Posted 29 March 2007 - 03:02 AM

Most "real" printers are continuous contact printers. The contact bit means that (as you envisage) the negative and the rawstock are sanwiched together and run emulsion to emulsion on a large sprocket wheel (to keep them in register) past a light to expose the stock.

The image comes out back to front (but it is already, on the negative, spo it reverts to the right way round, if you project the print with the emulsion facing the projector lamp.

The continuous bit means that you don't need the intermittent flashing LED that you imagined. As long as the neg and the stock are in good and steady contact, they can run continuously past a continuous light beam and you will get a good image exposed on the print emulsion.

It's the "good and steady contact" that is the difficult bit in practice. You need consistent tension in the feed and takeup strands of both negative and rawstock - not so easy, but not impossible. Messrs Bell and Howell did it a hundred years ago.

The liquid you mention isn't water (that WOULD make neg and stock stick, fatally!). It's used in very fancy printers, the liquid is usually tetrachlorethylene (local environmental requirements are putting pressure on this) and the reason is to mask any scratches in the surface of the base of the negative. It's all about refractive indexes.
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#5 Mat Fleming

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Posted 29 March 2007 - 04:14 AM

I use a Steenbeck in a darkroom to print b/w with. We have masked various light leaks in it, as well as the screen and put ND filmters under the triangluar prism (about 4 'stops' worth). In front of the 'gate' there is a cardboard mask which makes the light shine through a narrow slit (about 5mm) and catches some more leak. there is also an improvised cardboard filter holder where we can put ND filters to adjust exposure. Neg runs on one pair of plates, print stock on another and it works like a dream running at normal speed with the normal steenbeck lamp on as long as the tension's alright so that the 2 films hold on properly.

Mat.
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#6 Christian Appelt

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Posted 29 March 2007 - 07:07 AM

Actually, you can find some vintage amateur printers for 16mm b&w home printing on eBay from time to time.
A company named Uhler made them at least until the 1960s, the last one went for 25$ or something in that range. Will do a better job than any homemade machine.

It is also possible to do contact printing with certain cameras if you have a bipack mag or wind the films together on a core or reel. I wouldn't take the trouble because film printing needs cleanliness and precision, except maybe for certain types of experimental films.

If you insist on building your own machine, start with a good camera or projector mechnism so you will at least have a decent film path. There was an old AC article called "Bipack with a Bolex", maybe you will find it at a library.
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#7 John Pytlak RIP

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Posted 29 March 2007 - 10:02 AM

One key to obtaining sharp and steady images on a contact printer is the relationship of the perforation "pitch" to the printing sprocket the original and raw stock are wrapped around. Bell and Howell found that a printing sprocket of about 12 inches circumference was just right to prevent slippage between a processed nitrate negative that had about 0.3 percent shrinkage from processing, and the unshrunken nitrate print stock. This legacy survives today, such that a "short pitch" (e.g., BH-1866 perf) negative is printed to a "long pitch" (e.g., KS-1870 perf) print stock. In effect, today's triacetate negatives are "preshrunk" to maintain the 0.3% pitch differential dating back to the days of nitrate film when Bell and Howell optimized continuouse contact printing parameters.
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#8 K Borowski

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Posted 30 March 2007 - 10:47 AM

In effect, today's triacetate negatives are "preshrunk" to maintain the 0.3% pitch differential dating back to the days of nitrate film when Bell and Howell optimized continuouse contact printing parameters.


Hey, glad to see you around again Mr. Pytlak.

So, is this just a matter of it being too complicated changing the equipment over instead of redoing the print stock to be compatible with "natively"-sized acetate film base? Does Estar base pose any challenge to this?

I bought a Uhler on eBay, not as obscenely cheap as $25, but still very cheap. Primarily designed for B&W. You'd have to do additive filter packs (adding Kodak Wratten Additive or subtractive filters between the lightsource and the two film strips) to correct color, which would make color correcting individual scenes impossible to do in a continuous manner.

I haven't used the Uhler yet, (will in two weeks for a B&W 16mm short though) so I am not certain if it has this particular feature, but I know from an old Naval photography guide ('47) that there's a contraption on some printers where you can notch the camera negative near the sprocket holes which would trigger the printer to change its exposure from one printer light intensity to another to allow for different printing intensities for different scenes, a very handy feature for printing the conformed cut negative without having to manually start and stop the machine for each scene change.

Also, you have to have access to a darkroom or at least a room that can be made dark when you're printning, as there is no protective enclosure around the print stock. You can work with color stock only in complete darkness or with a very very dim orange or green color safelight, and with B&W you can work with a deep red or amber safelight. Basically, this is something that requires either still photography or lab experience for you to be able to do easily.

Feel free to ask me any other questions and I'll try to help you as best I can.

One other problem I can think of is getting a lab to process print stock. Most don't normally process outside print stock, so they might charge a premium, or require a 2000 foot minimum, or have specific times only when they'll do it. I don't know if doing it onesself is feasible, unless you anticipate generating the volume to justify purchasing 40-*GALLON* kits of ECP-2 chemistry, or mixing similar amounts of D-16 or whatever they're currently using as the print developer agent for B&W print stock these days (all I know is that D-16 was current as of 1947 B) ). Finally, with ECP-2, although cyan soundtracks are commercially usable in theatres, I have no idea how you'd get access to a soundtrack processor for color prints. Basically, unless you have very expensive equipment to allow you to make newer cyan and digital soundtracks with 35mm (not sure about 16mm), you have to essentially develop the soundtrack as metallic silver, with a special soundtrack developer separately from the color developer for the rest of the film, which involves a very complex process that I not only do not completely understand, but couldn't explain even if I did. Maybe John can help us out here with how a soundtrack is printed and processed on 35mm printstock.

Regards,

~Karl
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#9 Robert Houllahan

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Posted 30 March 2007 - 03:41 PM

The liquid you mention isn't water (that WOULD make neg and stock stick, fatally!). It's used in very fancy printers, the liquid is usually tetrachlorethylene (local environmental requirements are putting pressure on this)



Is tri-chlor still legal in Australia? it has been outlawed in the US for 5 years? I think. We run Per-chlor in our wet gate, as I assume most other US labs do.

-Rob-
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#10 John Pytlak RIP

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Posted 31 March 2007 - 10:54 AM

Is tri-chlor still legal in Australia? it has been outlawed in the US for 5 years? I think. We run Per-chlor in our wet gate, as I assume most other US labs do.

-Rob-


1,1,1-trichloroethane (methyl chloroform) can no longer be manufactured per the "Montreal Protocol", since it can deplete the upper ozone layer. Any still on the market is recycled material. Kodak won the EPA 2003 Stratospheric Ozone Protection award for developing Particle Transfer Roller (PTR) film cleaning technology that has minimized the need for solvent cleaning. (I led the development team):

http://digitalconten...k_receives_epa/

Tetrachloroethylene (Perchloroethylene, "Perc") is used for wet printing and film cleaning. It's main use is by the dry cleaning industry. Disposal, and vapors are regulated, but it is not banned. Most labs have efficient recycling systems for perc liquid and vapors.
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#11 Nick Mulder

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Posted 31 March 2007 - 03:28 PM

Well,

thanks for all the comments folks - I've got a little project or two that I'd like to keep %100 funded by the gear and stock I already have here and edit/cut using the same moviola hence the requirement for a cheap printing method -

The final output method I am still working on - home brew 16mm to 35mm optical blowup with sound anyone?? :huh: - but I may have found a cheap telecine, not sure exactly what it is but I found it at work in the storage room affectionately called 'the morgue' - it had two 16mm projectors mounted at 90deg to each other which disappeared into an array or mirrors which seemed to be fixed to solenoids of some variety, this collection of mirrors then poked its nose out and pointed at an Ikegami video camera -

'It' whatever it is (help anyone?) hasn't been used for around a decade and has been recently acquired by someone who I can still get in contact with after a bit of telephone twistaplot, he was 'going to get it working again' but never got a chance to really question him about it first - In the meantime I've heard that despite his intentions it may well be still sitting around doing nothing ...

I'm going to get in touch with him, but any info as to what it might be would help ...
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#12 Clive Tobin

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Posted 01 April 2007 - 12:25 PM

...two 16mm projectors mounted at 90deg to each other which disappeared into an array or mirrors which seemed to be fixed to solenoids of some variety, this collection of mirrors then poked its nose out and pointed at an Ikegami video camera...


This certainly sounds like an old style TV station type film chain multiplexer. The projectors are probably 24 FPS with synchronous motors, gearbelt drive and 5 blade shutters. The mirrors and solenoids determine which projector has the honor of being seen by the camera.
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#13 Nick Mulder

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Posted 01 April 2007 - 02:53 PM

This certainly sounds like an old style TV station type film chain multiplexer. The projectors are probably 24 FPS with synchronous motors, gearbelt drive and 5 blade shutters. The mirrors and solenoids determine which projector has the honor of being seen by the camera.

I think I remember that word being used yes ... How close am I to a telecine ? (For offline purposes only) Would the camera be synced properly with the camera shutters - or does the 5blade system take care of that ?
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#14 Charles MacDonald

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Posted 01 April 2007 - 08:19 PM

I think I remember that word being used yes ... How close am I to a telecine ? (For offline purposes only) Would the camera be synced properly with the camera shutters - or does the 5blade system take care of that ?

The TV staion would have called it a Telecine.

Shows used to be regualrly sent to staions via 16mm film, and of couse any local news coverage would have been done by carting a Cp-16 or an Auricon arround, and running the "Film at 11"
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#15 Clive Tobin

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Posted 05 April 2007 - 07:28 PM

I think I remember that word being used yes ... How close am I to a telecine ? (For offline purposes only) Would the camera be synced properly with the camera shutters - or does the 5blade system take care of that ?

For making a contact print you don't need anything approximating a telecine film chain. Basically you just need to sandwich the original and print stock together emulsion to emulsion over a large sprocket with a light bulb inside it. A sync block (synchronizer) would probably sort of work, it is normally 40 frames the same as the printing sprocket in a B&H or Peterson type printer. You need to pull the film through at a steady rate or the exposure will change. There is no shutter or intermittent pulldown mechanism needed.

5-blade shutters are only used in second-rate equipment for transferring film to NTSC video. Usually the projector is driven by a synchronous motor through a timing pulley pair at 24 FPS referenced to line frequency. The 5 blades gives a 120 Hz flicker rate which is close enough to twice the 59.94 Hz NTSC field rate that usually no flicker is visible. The 5-blade shutter gives blended film frames, where a video field frequently has information from two adjacent film frames, instead of the 2-3 pulldown in high end gear where a given film frame winds up on exactly 2 and 3 video fields in a predictable sequence.

If you are in a PAL country you would instead want a 2 blade shutter and run the film at 25 FPS to equal the 50 Hz PAL field rate. But none of this applies to continuous contact printing.
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#16 Paul Bruening

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Posted 07 April 2007 - 10:52 AM

Clive knows. Always listen to the Clive. He is the Clive and there is no other Clive.

Good to see you again, Mr. Pytlak.
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#17 David Marino

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Posted 18 April 2008 - 12:16 AM

I was curious about trying this method with my moviola, and just wanted to know what ASA film stock you use for this. I was thinking about using a b+w negative stock with a 64 ASA and was wondering how accurate this method combined with this stock would be at capturing the tonal range of my reversal print.
Thanks,
Dave







I use a Steenbeck in a darkroom to print b/w with. We have masked various light leaks in it, as well as the screen and put ND filmters under the triangluar prism (about 4 'stops' worth). In front of the 'gate' there is a cardboard mask which makes the light shine through a narrow slit (about 5mm) and catches some more leak. there is also an improvised cardboard filter holder where we can put ND filters to adjust exposure. Neg runs on one pair of plates, print stock on another and it works like a dream running at normal speed with the normal steenbeck lamp on as long as the tension's alright so that the 2 films hold on properly.

Mat.


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#18 Mat Fleming

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Posted 22 April 2008 - 10:17 AM

I was curious about trying this method with my moviola, and just wanted to know what ASA film stock you use for this. I was thinking about using a b+w negative stock with a 64 ASA and was wondering how accurate this method combined with this stock would be at capturing the tonal range of my reversal print.
Thanks,
Dave


I have used 7363 high contrast positive stock (usually used by labs for titles and effects) and Agfa ST8 (usually for optical sound recording). They dont have an asa rating but it's probably something like 4asa. I think any print stock would work, and you just adjust the ND filters accordingly. Once we tried shooting Ektachrome camera film, cross processing it and printing back to the same stock and cross processing again. looked alright if your into a grungy look.

Mat
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