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Mike Sulzberger

Aaton LTR Excessive Jitter

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I recently purchased an Aaton LTR and got the first roll of test footage back. This is Vision 3 500T processed at CineLab. The person I purchased the camera from said he had been using the camera regularly with no problems. As you can see in the clip I've linked to, there is excessive jitter. At about 35 seconds, the film jumps out of sync to the shutter. At least I think thats what happened. From there on, you will see I am getting a double exposure. I am thinking I messed something up in loading the magazine. I could only find a good video tutorial for loading an Aaton XTR. It had me do two finger widths of space between the film and the pressure plate. What did I do wrong?

 

https://youtu.be/LCX52RAc5c0

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In first 34 seconds, I would say, you´ve got short loop in loading - that is the thing Aatons don´t like - so jitter is caused by that.

But the rest, from 35 till end, is really out of sync shutter. And I don´t understand how can be that done.

Shutter and pull-down claw are mechanically connected with main axle from motor, so you can´t move them out of sync by yourself.

 

Maybe try to shoot another short test, with a little bit bigger loop, and you will see.

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If you're starting to get out-of-phase pictures, I reckon something's getting loose in the camera's mech.

 

John S

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From 35s you can see a frame line. Is it a registration issue with the scanner/telecine? You could look at the neg with a loupe magnifier and see straight away. Probably see that without one.

 

Rob from Cinelab is often on the forum. He will probably know what's up.

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Thanks Matej, John and Gregg for your insight. I got the negative back today. The camera did indeed jump out of sync with the shutter. All of the footage after about 35 seconds has a double exposure on it. I've sent the sample off to Bernie at Super16Inc. I'm guessing he is going to tell me to send the camera in. I actually think I had two problems. As Matej pointed out, I think I had too small of a loop when I loaded the magazine and that is what caused the initial jitter. I've since found some information that says the magic number is 14 frames of loop for an Aaton LTR. That may have then caused the gate to become out of sync with the shutter, but I think even too small of a loop shouldn't have caused a sync problem. Will post again when I have a definitive answer from Bernie on what happened.

Edited by Mike Sulzberger

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Update: I took the lens and magazine off and, using the inching knob, watched the claw in relation to the shutter. Indeed, the claw is in the middle of the pull down when the shutter opens. Talked to Bernie at Super16Inc who tells me the older Aatons use a belt while the newer Aatons used a chain. My serial number is in the 200's, so clearly an older camera. The camera is now on it's way to Bernie for a thorough going over. Hope this info can help the next Aaton owner when trouble crops up.

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That's exactly what happens when you lose the loop. The pulldown can only pull down so far and it pops off the perf and makes quite a racket. Honestly, the camera should have sounded really bad during all of this. It should make very little to no noise when running. I've actually done this purposely to get that look, so I know that's what happens when the upper loop is lost.

 

In terms of timing, LTR's and XTR's are direct drive. There is a shaft that comes off the motor which directly drives the pull down and then a worm gear that drives the shutter from that main shaft. The LTR's have a direct drive for the magazine, where the XTR's have a toothed belt. So I don't know what he's talking about unless it's something a lot older I haven't seen, but I've been in a few LTR's and XTR's.

 

The only way to get it out of time is to either slip the shutter OR the gear that's part of the pull down. It's a super robust assembly and I personally have never seen one fall out of time.

 

I think what you're seeing is the shutter open when the pull down is going back into position before the next pulldown.

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As a former LTR54 owner and current XTRProd owner I can just guess that the loop was too short or if the camera was making some sound that the magazine needed to be reseated with the loop pulled out so it seats in the middle.

 

I have not ever had an Aaton where the shutter / claw phase is off.

 

Both the LTR and XTR have a toothed belt in the magazine which drive the takeup and sprockets in the mag.

 

The LTR has a mechanical mechanism which drives the mag from the body and the XTR has a magnetic clutch which drives the mag from the body.

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