film magazines

[Filip Plesha]

can someone explain to me in a few words, how do those single-axel magazines work. Where does the film go when it's exposed? Is it side by side with unexposed film on the same axel? (that would make the magazine quite wide)

[Filip Plesha]

So, nobody has time to spare or I don't deserve an answer to such a stupid question? ;)

[Rik Andino]

Do you mean coaxial magazines?

 

They're a simple concept. The magazine has two sides put side by side

The simplest way to explain it is--->sorta like an Oreo (two cookies side by side)

 

It's quite hard to explain without pictures but...

A coaxial magazine has both sides (the take up and the feed) stuck together

The feed compartment is on one side of the mag (right for Aaton, left for Arri SR)

And the Take-up compartment is on the other side of the mag.

 

Depending on the concept you either pass the film through the pressure plate

Which is ingeniusly already attached to the magazine

And then thread on the take-up side or you (Like the Arri SR)

Or push the film through to the take up side then pass it through the pressure plate

And then thread it again as it comes back in to the feed compartment

(Like on the Eclair or Aaton).

 

It's a quite simple concept

Coaxial magazines are easier to load than Mitchell mags or Displacement mags

And can make the camera shorter (but longer)

 

 

The Aaton LTR/XTR and the Arri SR1/2/3 both have coaxial mags

 

Check out these manuals

 

http://www.cinematography.com/forum2004/in...?showtopic=2750

 

http://www.cinematography.com/forum2004/in...?showtopic=3694

 

http://www.cinematography.com/forum2004/in...?showtopic=2746

 

http://www.cinematography.com/forum2004/in...?showtopic=2747

 

I would also recommend you check out the ACS manual

They have lots of good illustrations there

And Perhaps also The Professional Cameraman's Handbook.

 

The best way to understand a coaxial magazine is to see if in person

Perhaps you can go to your local rental house or Film school

Or meet someone who has a camera with a coaxial mag

Such 16mm cameras like ECLAIR, AATON, and ARRI SR all have coaxial mags

 

So does the Aaton 35, the Arri 35BL1/2/3/4, and the Arri 535

 

Anyways good luck and I hope you were able to understand my answers

[Filip Plesha]

Yes, I get what you mean, I've suspected something like that

 

thank you

[Mike Panczenko]

The 535 and 35BLs do, but the Aaton 35 is displacement.

[Rik Andino]

The 535 and 35BLs do, but the Aaton 35 is displacement.

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It's a displacement magazine? Even the Aaton 35-III?

 

I've don't work with 35mm usually, and don't AC much

Only worked with the 35BL and the 2C

So I don't really know about the Aaton 35.

 

But since it looked so much like the XTR I thought it had the same magazines

Gosh it looks too small to be a displacement magazine.

 

Well thanks for enlightening me.

[Michael Nash]

It's a displacement magazine? Even the Aaton 35-III?

 

Gosh it looks too small to be a displacement magazine.

 

 

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That's kinda the point behind having a displacement mag! ;) It only has to be marginally bigger than one roll of film, since the takeup roll "displaces" or fills the void left in the exposed part of the feed roll. Operating the Aaton 35 is a lot like shooting Betacam in terms of size and weight.

[Rik Andino]

It only has to be marginally bigger than one roll of film, since the takeup roll "displaces" or fills the void left in the exposed part of the feed roll.

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But isn't that also the same principle in a coaxial magazine?

 

I looked at the Aaton 35 manual and the mag is a displacement

It's one of the strangest displacement mags I've seen though

Do they make 1000' versions?

It would make the camera very heavy...

Why didn't Aaton decide on a coaxial mag like they did for the XTR?

[Guest Sean McVeigh]

But isn't that also the same principle in a coaxial magazine?

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A coaxial magazine places the reels side-by-side coaxially as the name implies (both spin around a common center point). A displacement magazine is very similar to a traditional 'mouse ears' style magazine, except that the spools are not stationary. Here's a quick diagram... pardon my poor ascii art.

 

A ((((1)))) B (2) C

 

A,B,C are empty spaces in the magazine. Imagine a set-up in which spaces A,B,C are kept to a minimum throughout the entire run. As film unspools from core 1 onto core 2, space A becomes larger, while space C becomes smaller. (assume space B stays relatively constant for argument's sake). This is how a typical magazine works. In a displacement magazine, as the film spools off of core 1 and onto core 2, the entire assembly shifts from right-to-left, meaning that spaces A and C neither grow nor shrink. The net result is that no space is wasted in the magazine and it can be kept sufficiently smaller than a traditional magazine.

 

In a coaxial magazine, it's an entirely different beast. It's basically a traditional magazine, but folded in half, making it roughly half as tall and deep, but twice as wide. No real net savings in space (volume occupied). A displacement magazine can in theory be about 33% smaller than a traditional magazine.

 

Hope that makes sense.