Possible magazine flashing on 416 - feedback / thoughts quested

[James Malamatinas]

Today we received the report from the lab for a 16mm job that we've just finished and one roll is coming back with strange orange/red, pulsating, flashes on one side of the frame. Video below:

https://clipchamp.com/watch/DWOV51Zu3Ik 

We shot on an Arri 416 and the initial thoughts from the lab is flashing, however a few things don't line up and I'm hoping someone can help me understand the cause a little better. I've loaded hundreds of rolls of both 16mm and 35mm and never encountered this issue. 

• The flare is on the opposite side of the perfs on the Arri 416. This side of the film is closest to the platter on both feed and take-up side and to my mind should be less likely to be exposed to flashing and light leaks. Theoretically I imagine it could have been exposed on that side if it was exposed to a leak prior to to entering the mag e.g a light leak in the bag, but then I would have expected to see the problem on all rolls over our 3 day shoot. 

 

• The flare is consistently pulsating, this suggests that it's following the rhythm of the mag spinning. What does this indicate? If there was a leak in the mag then I'm assuming the leak would be consistent? 

 

• The flare is scratchy with lines throughout it, does this also indicate something inparticular? 

Other observations:

• This magazine had been used for other rolls which did not have the issue. 
• This roll number in particular was actually used on two different camera bodies, and the effect was consistent on both suggesting it's not a body issue. 
• It was a 400' fresh roll of 200T
• Shooting conditions were warm, about 30 degrees however stock was kept in a fridge overnight when not on set, and on set in an ice cooler kept under a shaded EZ-up

 

Does this 100 percent line up with a mag flashing, or are there other possibilities including on the processing side? All thoughts welcome and can provide more information if necessary. 

 

[Dom Jaeger]

The video link isn't working for me, but a few thoughts:

The film in a mag spins at a constant rate, so a mag leak would be continuous, except for just before or after a cut (depending on which side of the mag has a leak) where you would have a more intense leak due to the film being stationary for a while. The nature of the leak would also change in response to the camera position and exterior light conditions.

The only place where you have intermittent motion is the loop between the sprockets, so in the throat or gate area, but a leak here would result in a pulse every frame.

Usually if there is one roll with a weird light leak but all the other rolls are fine, including ones from the same mag, then it's more likely you have a lab issue (or a loading issue) than a camera one. If this roll was used on two different cameras as well, I would definitely say it's not a camera problem.

If the roll was exposed on one side by a narrow beam during loading or unloading or in the lab, you would get periodic flashing, but it would change in frequency because each layer of a roll is a different length. 

[Tyler Purcell]

The main issue with the 416 mags is the gasket for the counter, it fails. So you're moving the mag around and you get it in the sun by accident and it flashes the side of the roll ya know? I suggest having the mags gone through by a tech and having them check that seal. 

[James Malamatinas]

Thank you for the replies. 

@Dom Jaeger here is a YouTube link if that works for you. I have also managed to secure rushes for the whole role and the flashes are the same throughout other than the pulsing become steadily quicker in frequency (because the diameter of the film is getting smaller on the roll I'm assuming). Annoyingly the lab has trimmed the roll-up between shots so I can't see how it appeared during that. 

@Tyler Purcell that's a good suggestion and we're having the rental house investigate the mag today. 

Out of interest, if it was a lab issue what kind of cause would it be on their side?

•  

[Mark Dunn]

deleted

Edited March 7, 2023 by Mark Dunn

[Dom Jaeger]

9 hours ago, James Malamatinas said:

the flashes are the same throughout other than the pulsing become steadily quicker in frequency (because the diameter of the film is getting smaller on the roll I'm assuming).

Yes, so the roll has been flashed before exposure. If it was afterwards, the flashes would decrease in frequency (because the start of the footage would be at the core). Assuming it was a fresh roll that means it was either flashed during loading or in the feed chamber. 

I wouldn’t have thought a leak through the mag counter window would reach all the way across the roll, but I’m not familiar enough with 416 mags to say. Isn’t  the counter window between the platines? Anyway, you’re having it checked so you’ll find out soon enough.

[James Malamatinas]

Thank you for the extra clarification.

If that’s the case I’m still struggling to understand the pattern of the flashing just from a technical side and would appreciate any help in understanding how it arises.

If it was from loading then this was done in a bag. At no point did I notice a zip undone, but if this was somehow the case how does the pattern of flashing stay consistent through the whole roll - would the more tightly coiled, inner part of the fresh roll not receive less exposure to the light and therefore show reduced issue?

Also, how would the flashing be on the inner side of the stock, rather than the more exposed outer? If it was somehow in transferring the film from can to the feed side that handling isn’t is erratic in the sense of holding the film in one hand, moving it into the mag, feeding it etc - wouldn’t that be an uneven pattern of flashing?

Thanks for any input.

 

 

 

 

 

[Tyler Purcell]

18 hours ago, James Malamatinas said:

@Tyler Purcell that's a good suggestion and we're having the rental house investigate the mag today. 

Out of interest, if it was a lab issue what kind of cause would it be on their side?

For sure supply side issue on the magazine, that's where it always happens with that silly seal. 

[Dennis Toeppen]

Here's what it looks like when mag is opened accidentally. Intensity of light exposure wasn't consistent across the whole platter, so it appears to pulsate. Pulse occurs with each revolution of the supply side platter.

 

Edited March 8, 2023 by Dennis Toeppen

[Mark Dunn]

1 hour ago, Dennis Toeppen said:

Here's what it looks like when mag is opened accidentally. Intensity of light exposure wasn't consistent across the whole platter, so it appears to pulsate. Pulse occurs with each revolution of the supply side platter.

 

Save for the intensity, that looks awfully (word chosen carefully) similar, with the ragged streaks. Even the frequency (about 2.5sec at the start) is the same, getting shorter towards the end, about 1.5sec.

Edited March 8, 2023 by Mark Dunn