Jittering ghosting on Arricam ST, 86.4° shutter angle

[Leander Ott]

Hi everyone,

I recently shot a project on 35mm 4-perf using an Arricam ST and Master Primes and encountered an issue: there’s vertical ghosting in the image, and the ghosting itself is jittering slightly. In some shots it's more noticeable than in others.

The camera was set to 24fps with an 86.4° shutter angle, selected because it’s flicker free for 24fps in a 50Hz region (Europe). I adjusted the shutter from the standard 172.8° to reduce motion blur, as still frames from the footage will be used in a print magazine.

It doesn’t appear to be filter-related. The ghosting is not static — it shifts slightly from frame to frame. For reference, there was only a single ND filter in the matte box, with no other optical elements in place.

I’m considering whether this might be a timing or phase issue. Has anyone experienced this when using a narrow shutter angle like 86.4° on the Arricam ST? Or could this indicate a possible misalignment in the camera movement or registration?

Due to a tight schedule around a bank holiday, I wasn’t able to shoot a test and get it processed in time, so I had to rely on the rental house's assurance that the camera was properly set up.

Unfortunately, I can't share any footage and only a censored still of the jittering, but I hope you still see what I'm talking about.

I’d appreciate any technical insights or similar experiences.

Thanks in advance.

Leander

[Leander Ott]

I just realized that it can't come from the smaller shutter angle, as the first takes that were shot at 172.8° show the ghosting as well. Must be a registration problem then, right?

Could someone have used a timing shift box on that camera before and it didn't reset itself after it was unplugged?

[Dom Jaeger]

I managed a rental house service department with Arricams for 10 years and never had a steadiness or timing issue. They are pin registered, so you won’t get unsteady images unless something is really wrong with the movement. The timing is set electronically, so I guess there is some chance it was out.. was the camera recently converted from 3 perf to 4 perf? Timing needs to be checked/reset after that procedure, but I never had a problem with timing after doing conversions.

Double check the film neg in case it’s a scanning error, then get the rental house to shoot a steady test to check the camera. 

[Leander Ott]

Hi Dom, thanks for your insight, really appreciate it!

I will check with the rental company that supplied the camera to see if it had been converted recently or used with a timing shift box and if they can do a test.

The lab also suggested that it could be a registration problem either caused by mis-loading or even by dirt somewhere in the camera and mag unit as the reel was travelling through. But since the effect is noticeable on all four mags we used, I doubt that. What do you think?

Thanks for your help!

Leander

Edited July 19, 2025 by Leander Ott
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[Aapo Lettinen]

Not an Arricam expert but on pin registered camera it 100% looks like mirror timing issue to me if there was no weird filtration which could cause it. Because these cameras have electronic shutter syncing it is pretty certain there is something wrong with the timing

[Dom Jaeger]

1 hour ago, Leander Ott said:

The lab also suggested that it could be a registration problem either caused by mis-loading or even by dirt somewhere in the camera and mag unit as the reel was travelling through. But since the effect is noticeable on all four mags we used, I doubt that. What do you think?

No, Arricams don’t really get registration problems from a bit of dirt.. they are pin registered. As for misloading, you’d have to seriously screw up the camera lacing to cause a pull on the film while it’s registered - it would sound awful, damage perfs and probably just cause a jam error. And it’s highly unlikely to happen on four seperate mags, as you point out.

If you’ve checked that the ghosting is definitely on the neg itself and not a scanning issue, then I would be looking at the camera shutter timing, though normally that is also pretty reliable on Arricams. But I don’t know the camera condition or service history, so you need to discuss this with the rental house and possibly have them shoot a test.

[Tyler Purcell]

Yea no way it was loading. 

As Dom said, timing is done electronically. 

This ghost isn't a lot out of time, it's very very very close to being right. 

The only thing I can think of is that the camera had recently gone through service, perhaps a part like the shutter motor was replaced and never re-calibrated because the tech didn't have the Arri module to do that. Really it could be that simple. 

[Leander Ott]

Thanks for your suggestions!

I'm in conversation with the rental house now to see what could have caused it and if they can do a test.