Film-Tech Forum ARCHIVE: Jittery Film

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Posted by James Paterson (Member # 4669) on 02-20-2009, 07:03 AM:

Hi, i have a very nice kinescope print i have been trying to transfer on my home made telecine set up, its working brilliantly except for the picture "jittering"...

YOU TUBE LINK HERE

I am using an early 16mm SIEMENS 2000 projector because it can be sped up to 25fps for PAL transfers. I have tried cleaning the gate and film path, etc and have used filmguard on the print.

I wondered if anyone can give me some ideas to try to eliminate this jittery problem?

Posted by Robert Minichino (Member # 3495) on 02-20-2009, 10:13 AM:

Have you tried increasing the film gate tension (if it's adjustable)? If the tension isn't high enough the momentum of the film will keep it moving after pulldown, resulting in vertical jitter.

If all else fails, if you can find someone with video editing software you should be able to stabilize the image digitally. Adobe After Effects has a tool that you can use to stabilize motion (if there's any way to transfer the image complete with sprocket holes in frame that might help if the original is steady).

Posted by Monte L Fullmer (Member # 2797) on 02-20-2009, 01:11 PM:

Old 16mm projectors, esp if they use a retractable pulldown claw in the trap, (being called the shuttle assembly), instead of a rotating intermittent sprocket to pull down the film through the trap, will develop grooves at the base of the one side of the teeth that is pulling down the film through the trap. Any form of extra gate tension will not help - the shuttle assembly will need to be replaced.

Also, the cam assembly, which is attached to the shutter blade that drives this shuttle assembly also can get worn where the shuttle will not function correctly. This also needs replaced.

Sorry on this, if this is the cause - good luck - Monte

Check this one out

Posted by Joe Tommassello (Member # 4632) on 02-20-2009, 03:21 PM:

James:

If your film isn't torn in the sprockets I definitely think a little extra pressure in the film gate will help. Make adjustments in the smallest increments possible until it stops.

Posted by Ian Parfrey (Member # 5122) on 02-20-2009, 03:43 PM:

HI James.

Some kinescope prints, due to the type of camera used to photograph the CRT, have jitter on the film itself. Due I think to the very rapid pulldown in those cameras. If my theory serves me right, the pulldown occurs during the flyback of the scanned electron beam. 25 millisecond pulldown rings a bell somewhere but Im by no means certain on that.

In light of this, I would first, I would screen the print more than once to see if the print "jitters" in the same place eveytime. This should eliminate the print being at fault.

If the jitters are random, and the Film-Guarded print still plays up, then I would agree with Monte in that gate pressure and claw condition may well be a factor.

To determine if the projector is at fault, screen the print on another projector, preferably one with an intermittant-such as a Bauer Selecton. These are a popular machine and a quick phone around the cinemas may well locate one for you to use. One was at the Village Centre in Cinema 4, one at RMIT in Queensberry St Campus, one at the Erwin Rado Cinema in Richmond. Im sure that Dave Thomas at MIFF ( Melbourne International Film Festival) will direct you. He's a top bloke.

Good luck.

Posted by Julio Roberto (Member # 4976) on 02-20-2009, 04:24 PM:

Just fix it digitally with a stabilizing filter or software. Faster and covers all possibilities (i.e. jitter being in the print itself).

Posted by James Paterson (Member # 4669) on 02-20-2009, 07:14 PM:

Thanks for all the replies everyone,

first question is, how do i know if my siemens projector has adjustable gate pressure? My guess is it doesnt as there is no knobs or anything i can see that would do this. I did find however that ever so slightly opening the gate by moving the lense forward as you do when you thread the film lifted the pressure somewhat and would ever so slightly reduce the jitter...but then it would loose the framing as i had it open too much!! - so it leads me to beleive maybe the pressure is the issue.

Secondly, as far as stabilisation filters, what have you tried that works? I tried a few virtualdub filters as well as some commercial ones and they "sort" of worked slightly but made some really weird effects to the frame, i cant say it is easy to fix this way.

You may remember i was looking for a magnetic playback projector, the siemens is supposed to do this but it appears to be missing its audio section for the magnetic playback.

So, I'm still looking for a good "telecine" projector with magnetic capabilities, if anyone knows of one here let me know...unfortunately i cannot afford the exhorbitant prices they are selling for on ebay...(around $500+) currently a siemens 2000 on there for $750 !

Posted by Monte L Fullmer (Member # 2797) on 02-21-2009, 03:53 AM:

What happens when you put light pressure on the surface of the film with your finger just before it enters the trap, does the jittering cease?

The bounce in that YouTube video does show both possibilities - a loose trap, or worn shuttle teeth.

Posted by Julio Roberto (Member # 4976) on 02-21-2009, 07:51 AM:

Only seldom I had to stabilize footage, with FCP smoothcam i.e. Only once from film with daVinci revival. Mostly had to do a bit on a short scene or two manually with motion tracking on After Effects.

Heard good things on Pixelock iStabilize software. Get their free trial and see if it works for you.

About the weird effects with the borders you mention, you have to tell filters like Steadymove what to do with them, as they would, of course, change. I.e. zoom-in-and-out, zoom to minimun, or crop the final size.

Since you are telecining yourself, if you can change aperture plates on the projector (or don't mind ruining one), you could file it down to show the film's borders. Include them in your transfer, and then motion track them with After Effects, i.e. Then just crop them or zoom-in if you need the same size as it originated in.

That would be absolutely "rock solid" to borders on film at pixel level. No software guessing the movement and possibly overshooting a bit during zooms, fast pans, etc. Only in-camera jitter would remain.

Posted by Monte L Fullmer (Member # 2797) on 02-21-2009, 09:17 PM:

Okey, gonna throw in the obvious here: What does the image on the screen looks like when you toss in some other 16mm film - pict holds steady or still jitters?

Posted by James Paterson (Member # 4669) on 02-23-2009, 03:19 AM:

tested another film and it is rock steady..

so i tried the kinescope again and still jittery...which suggests a problem with the film...however when tried with a projector some time ago which was 24fps it worked smoothly...so why does it not go smoothly in this one?

Posted by Ian Parfrey (Member # 5122) on 02-23-2009, 06:14 AM:

Grab a loupe or a lens and scrutinise the sprocket holes. Its acetate remember and may be prone to brittleness. The first runs through the projector may have done minor damage. Even if this is the case, a machine with an intermittant sprocket instead of the claw movement may produce a steadier picture.

Posted by Christian Appelt (Member # 1067) on 02-23-2009, 09:07 AM:

Gate tension in Siemens 2000 projectors can be adjusted, although it is rarely necessary. Open the lamp cover, remove lamp and mirror and look at the back of the film gate (depending on the year of maufacture, there may be an additional cover lid to remove). There are two screws that can be adjusted.

This should be done only after the front pressure parts have been cleaned and checked. I spoke to a service guy who used to repair 2000s from schools in the 1970s, and he remembered just one single case where it was necessary to readjust the gate assembly - the projector had been dropped and went down a staircase...

If the Siemens works for your purposes, I wouldn't exchange it for a newer machine that most likely contains a number of aging plastic gears - BTW, most spare parts for Siemens are still available cheaply because it was used widely in schools.

Posted by James Paterson (Member # 4669) on 02-23-2009, 11:02 AM:

do you happen to know the pin outs on the strange din output plug for mag sound ? I ask because i cannot use it as the amplifier add on that it normally plugs into is missing and i have no way of knowing what pins go where to get the sound out?

Also, on rewind the variable resistor thingy inside it gets red hot (it the thing that has little coiled springs wound over it)

I've removed the original bulb and mirror assembly and have a new LED system instead for back illumination...the original bulb actually ballooned out and exploded !

Posted by Monte L Fullmer (Member # 2797) on 02-23-2009, 01:34 PM:

the same projector (Siemens) that you ran it at 24fps?.... wonder then if the variac on the projector has a bad spot causing motor speed variations then...

quote: James Paterson
Also, on rewind the variable resistor thingy inside it gets red hot (it the thing that has little coiled springs wound over it)

There isn't a 'REWIND' switch that bypasses that variable resistor so it doesn't get that hot during the 'REWIND' mode?

Posted by Christian Appelt (Member # 1067) on 02-23-2009, 03:50 PM:

This is the only major construction fault. The original tungsten bulb and the resistor generate a lot of heat, and with 2000 ft. (600m) reels, the rewind power is too weak.

Generations of school teachers have damaged films when it stopped over the lamp cover [Smile]

- to be fair, when that machine was constructed in the late 1930s, most of the scientific and education films were no longer than 10 to 12 minutes which the rewind mechanism handles without problems.

Sorry, I cannot tell you the pin outs because my machine is optical only and has a later date amp. A word of caution: If you ever change the lamp assembly (converting to quartz lamps is no problem) be careful with the core of the resistor because it contains asbestos. Not dangerous in operation, but take proper precautions if you handle or damage it.

Posted by James Paterson (Member # 4669) on 02-26-2009, 05:23 AM:

here are some photos of the din plug, the lead has two wires which inside have an insulated cable and one not

I've no idea how you wire this to get the sound out of the machine to a video camera as i have never wired a magnetic head before

image 1