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How much of the cartridge has been used?


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#1 darren walsh

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Posted 26 March 2007 - 02:06 PM

Hi There

i'm hoping someone can help. I have a super 8 cartridge that's been used roughly between 10 secs and 1 minute. What I want to know is, is there a way of telling how much has been used / exposed just by looking at the cartridge?

Thanks in advance
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#2 Dan Salzmann

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Posted 26 March 2007 - 02:29 PM

Unfortunately no.
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#3 Alessandro Machi

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Posted 26 March 2007 - 02:50 PM

Hi There

i'm hoping someone can help. I have a super 8 cartridge that's been used roughly between 10 secs and 1 minute. What I want to know is, is there a way of telling how much has been used / exposed just by looking at the cartridge?

Thanks in advance


Some day, I don't know when, I want to create some type of device that would allow one to figure out how much film is left in a super-8 cartridge. Because the film starts on one half side of the cartridge and ends up on the other half side, the center of gravity of the cartridge probably changes.

If I (or anyone else who would like to try) could pinpoint the center of gravity when a cartridge is new, then do another test when a film cartridge has been completely shot, then in theory all the points in between would represent some type of percentage that could be translated into film footage already shot.

By attaching some kind of extension to the cartridge (sort of like the pole a tightrope walker holds onto) and finding the center of gravity when the cartridge is new versus completely shot, one might end up with a measureable distance that could be converted into how much film has been shot.
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#4 Nick Mulder

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Posted 26 March 2007 - 03:37 PM

If I (or anyone else who would like to try) could pinpoint the center of gravity when a cartridge is new, then do another test when a film cartridge has been completely shot, then in theory all the points in between would represent some type of percentage that could be translated into film footage already shot.

Well, its not that hard - and you've even alluded to the method - use two pins ... either side in the same spot (so it doesn't flip sideways when enough force is applied to hold it by itself) then move it around testing each time until you find a point in which the cartridge is neutral... ie. it doesn't want to swing - If it does swing, the center of gravity will be along the line scribed from the pin point to the center of the earths gravity (ie. down) -
Once you have found it it should spin like a wheel would, ending up arbitrarily wherever the amount of force you applied to it ended it up...

easy!

Find the final point the same way - It'll be interesting to see if the transition as the cartridge is used is linear between these two points or follows some sort of slight curve

Hmmm, just had a thought - I don't know how the internals work of a super8 cartridge, are they like a cassette tape? or maybe some sort of funky dual concentric thing going on ? - still possible to do it though...
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#5 Alessandro Machi

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Posted 26 March 2007 - 03:57 PM

Hmmm, just had a thought - I don't know how the internals work of a super8 cartridge, are they like a cassette tape? or maybe some sort of funky dual concentric thing going on ? - still possible to do it though...


I think dual concentric is the right word???
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#6 Nick Mulder

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Posted 26 March 2007 - 04:00 PM

I think dual concentric is the right word???

Is that a statement or a question ?
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#7 Terry Mester

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Posted 26 March 2007 - 05:08 PM

What I want to know is, is there a way of telling how much has been used / exposed just by looking at the cartridge?

I don't understand why you want to be able to make this calculation. The Meter on the Camera would have given you a measurement of how much Film was used before you removed the Cartridge. There's nothing to stop you from finishing the Cartridge. Just run it until the Camera automatically stops. There's no problem for the Camera if it continues running after the Film is used up.

Hmmm, just had a thought - I don't know how the internals work of a super8 cartridge, are they like a cassette tape? or maybe some sort of funky dual concentric thing going on ? - still possible to do it though...

I've taken apart a Cartridge that came with a used Camera. On the front (supply) side, the Film is just coiled up -- there's no supply 'Reel' or anything like that. The Film unwinds nicely. On the back (take-up) side, the Clutch only forms a Spool which winds up the Film -- once again there's no Reel. There's a plastic mould case inside which forms the outer dimensions of a Reel for both the supply and take-up sides. This keeps the Film in alignment without the need for a Reel. What is particularly interesting is that the Camera gear mechanism can gradually (and accurately) reduce the speed of the Cartridge Motor as the Film is used. The more Film that is used, the slower the take-up Spool must turn in order to maintain a 'constant speed'. The Meter indicating Film usage is likely linked to this mechanism.
The Sprocket in the Film Gate exclusively advances the Film through the Gate. This means that there must be slack between the take-up Film coil and the Film Gate. The take-up Spool must not 'pull' the Film, and there are a couple of corners the Film must go around before reaching the take-up Film coil. If the Sprocket suddenly stopped moving, the pulling of the take-up Spool would likely break the Film since it cannot be pulled through without being pushed by the Sprocket. I wouldn't waste my money to buy a Digital Camera, but I hope to get a Webcam in which case I can take pictures of the Cartridge inside and post them on this Forum.
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#8 Alessandro Machi

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Posted 26 March 2007 - 05:27 PM

Is that a statement or a question ?


Yes!
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#9 Nick Mulder

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Posted 26 March 2007 - 05:28 PM

Yes!


hah hah - great ... really helpful
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#10 Rick Palidwor

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Posted 26 March 2007 - 07:38 PM

Not exactly an answer to the posted question but related:
One of my favourite cameras is the Nikon Super Zoom 8 or 8X Super Zoom because they tell you when a cartridge is finished, regardless of when it was loaded. Most cameras don't give that indication, as the film-end signals are linked the the footage meter and not the film itself. On the Nikon's it's linked to the film itself. Worth owning one of these strictly for shooting cartridges with unkown histories.
Rick
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#11 Alessandro Machi

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Posted 27 March 2007 - 03:41 PM

hah hah - great ... really helpful


Basically, anyone who owns two super-8 cartridges, one completely shot all the way through, and another that is completely new, could play around with the center of gravity issue and see what they see. I'm real curious to do some tests myself but they will have to wait for a couple of days.
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#12 darren walsh

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Posted 28 March 2007 - 05:00 PM

I don't understand why you want to be able to make this calculation. The Meter on the Camera would have given you a measurement of how much Film was used before you removed the Cartridge. There's nothing to stop you from finishing the Cartridge. Just run it until the Camera automatically stops. There's no problem for the Camera if it continues running after the Film is used up.

Hi, I had to take the cartridge out to see why it wasn't playing properly. So there's no real indication on the meter


Not exactly an answer to the posted question but related:
One of my favourite cameras is the Nikon Super Zoom 8 or 8X Super Zoom because they tell you when a cartridge is finished, regardless of when it was loaded. Most cameras don't give that indication, as the film-end signals are linked the the footage meter and not the film itself. On the Nikon's it's linked to the film itself. Worth owning one of these strictly for shooting cartridges with unkown histories.
Rick

That's really handy to know

Thanks for the replies
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#13 kevin jackman

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Posted 02 April 2007 - 11:02 AM

there is actually such a device that labs had. it holds the cart and weighs it.by weighing one side of the cart to the other it can acurratly tell you much much footage has been shot.i know a guy that has one. i havent seen it but he used to use it in the hayday of super8 but he only now processes still stuff. so yes there is a device out there that can do it.
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#14 Anthony Schilling

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Posted 02 April 2007 - 04:30 PM

I have a device for this... a small piece of white tape with ft used written in sharpy. just stick it on the back of the cart after you pull it. But don't forget to look at the footage counter :P
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#15 Jonathan Bowerbank

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Posted 02 April 2007 - 05:57 PM

i'm hoping someone can help. I have a super 8 cartridge that's been used roughly between 10 secs and 1 minute. What I want to know is, is there a way of telling how much has been used / exposed just by looking at the cartridge?


Uhhhh, yeah, no way to know. But Super8's relatively cheap anyways, just shoot it and bring along plenty of extra cartridges. They're so easy to switch out, I wouldn't ever get too hung up on how much is left on a roll.
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#16 Alessandro Machi

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Posted 02 April 2007 - 11:39 PM

There is actually such a device that labs had. It holds the cart and weighs it. By weighing one side of the cart to the other it can acurrately tell you much much footage has been shot. I know a guy that has one. I haven't seen it but he used to use it in the hayday of super8 but he only now processes still stuff. So yes there is a device out there that can do it.


Thanks for sharing Kevin. Any chance of you getting a picture of it on the internet? l wonder how common these devices were?
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#17 Rick Palidwor

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Posted 03 April 2007 - 01:19 AM

Uhhhh, yeah, no way to know. But Super8's relatively cheap anyways, just shoot it and bring along plenty of extra cartridges. They're so easy to switch out, I wouldn't ever get too hung up on how much is left on a roll.


Except that you often don't know when it ends, which isn't much fun, which is why I recommend one of those few cameras that actually tell you, like the Nikon 8X super zoom.
Rick


I have a device for this... a small piece of white tape with ft used written in sharpy. just stick it on the back of the cart after you pull it. But don't forget to look at the footage counter :P


Of course, but what about when you have a cartridge with an unknown history? I deal with a lot of them.
Rick
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#18 Mark Dunn

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Posted 03 April 2007 - 04:42 AM

there is actually such a device that labs had. it holds the cart and weighs it.by weighing one side of the cart to the other it can acurratly tell you much much footage has been shot.i know a guy that has one. i havent seen it but he used to use it in the hayday of super8 but he only now processes still stuff. so yes there is a device out there that can do it.


I'm not doubting you but can't see what use such a device would be to a lab. You can't clip-test Super-8. They either dev the whole cartridge or they don't. An exposed cartridge is readily identifiable, so you wouldn't need it to prevent processing of an undeveloped film.
Surely, the film is so narrow and the component mass distribution within the cart so imprecise that you'd need laboratory (physics, not processing) conditions to work out the CG.
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