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Arriflex SR2 mag S16 modification - what's different?


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Hi there,

I am new here, hello! 🙂My first question is about an Arriflex SR2 mag I just bought. I have a SR2 that was moified for S16 long time ago. Now I would like to know what modification I would need to do to use a normal SR mag with my camera. Is it only the pressure plate or are there any other modifications that I need to go through? I read somewhere that the tunnels must be widened but I dont really see why because the material is the same, isn't it? 🙂

Yours, D.C.  

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There are surfaces inside the SR2 mag that touch the film as it cycles thru the camera. These surfaces need to be machined back (relieved) so they don't touch and scratch the area of the film that is seen in the Super-16 frame.

Best, -Tim

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Axel Broda taught me the Arriflex 16SR & SRII Super-16 modification, it's not just the sprockets, it's also the ramps that lead up to the sprockets, we would "relieve" them as well. That way there was no way any part of the converted magazine would scratch the film in the Super-16 image area.

 

Best, -Tim

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2 hours ago, Tim Carroll said:

Axel Broda taught me the Arriflex 16SR & SRII Super-16 modification, it's not just the sprockets, it's also the ramps that lead up to the sprockets, we would "relieve" them as well. That way there was no way any part of the converted magazine would scratch the film in the Super-16 image area.

 

Best, -Tim

Yes, when we were modifying those mags for S16 at Panavision Sydney in the 90s we also removed material from the ramps as well as the sprockets.

I think companies like P&S Technik that specialised in S16 conversion also did so, but I have noticed over the years that not everyone who converted mags was so thorough.

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Hi everyone!

Thank you very much for your answers. I know some people who used their SR2 mags only with the new pressure S16 plates. Do you think that's very risky? Does anyone have experience with that?

Yours,

D

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2 hours ago, Deniz Cooper said:

 I know some people who used their SR2 mags only with the new pressure S16 plates. Do you think that's very risky? Does anyone have experience with that?

I’ve never heard of a S16 pressure plate for SR mags. The pressure plate doesn’t need modification. Millions of feet of film have been put through S16 SR2s and SR3s with unmodified pressure plates without a problem.

Here’s an old thread where I talked about the SR pressure plate design, and the absence of a “S16” pressure plate:

https://cinematography.com/index.php?/topic/73045-super-16mm/page/2/&tab=comments#comment-467423

 

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Hi Dom,

I wish you a happy 2021!
Thanks for your message.
That is what I meant:
Looks like it isn't 4:3 but s16.
I will study your link too.
Yours,
D.C.

V2129SRMagPresplate.JPG.acbab175c242f7b41ea84a3548c181c3.JPG

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14 hours ago, Deniz Cooper said:

Hi Dom,

I wish you a happy 2021!
Thanks for your message.
That is what I meant:
Looks like it isn't 4:3 but s16.

Happy 2021 to you too! Gotta be better than 2020 right?

That’s just a standard SR pressure plate. The raised little chrome rectangle is smaller than the film frame, and only exerts light pressure on the back of the film, along with the two side rail strips, to keep the film flat at the gate aperture. The rest of the plate doesn’t press on the film at all, but closes against the gate to form a channel slightly taller than the thickness of the film. So the film runs freely through that channel and only gets pressed slightly right at the gate aperture where it is exposed.

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Okay, I see.. But why are there different shaped chrome rectangles on the magazines?

I have one mag that was used for S16 and one that was used for 16mm and they look like that.. (picture attached)

For me it seemed to be 4:3 and S16 shaped rectangles.. 🙂 

20210103_151454.jpg

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You’ll find some variation in the height of that little pressure pad, but the width is the same. With S16 the frame gets wider, but the height remains the same, so I don’t think those variations have anything to do with S16, just a design evolution like the later soft plastic drive gears. Probably done to reduce noise, like the gears.
You’ll also find that the high speed mags have a different pressure plate design, which is not compatible with normal speed SRs, but again there was no specific S16 one.

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Yea the little center piece that pushes the film against the gate is not your problem. Your problem are the side rails which "CAN" damage the image area of the film. Notice how both side rails are the same size? That's "standard" 16. On a SUPER 16mm magazine, one side rail will be half the size of the other. Thus not touching image area on the film. 

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3 hours ago, Tyler Purcell said:

Yea the little center piece that pushes the film against the gate is not your problem. Your problem are the side rails which "CAN" damage the image area of the film. Notice how both side rails are the same size? That's "standard" 16. On a SUPER 16mm magazine, one side rail will be half the size of the other. Thus not touching image area on the film. 

Show us a picture of this Super 16 pressure plate, Tyler. 

The side rails pictured are not a problem. The pressure plate acts on the back of the film, as long as the gate rails (acting on the emulsion side) are machined back for S16 there will be no damage.
Think about it: why do you think it’s OK for the centre piece to push against the back of the film in the middle of the image area but a side rail that might slightly extend into it is not OK? 

All the SR3 mags I’ve seen were not manufactured with one narrower side rail on the pressure plate.. and SR3s were S16 compatible cameras. They look like this:

F3D2C6F6-432D-4DA1-A281-2650B05421C8.thumb.jpeg.1d157c192f015abd72fd0c4edc442c60.jpeg

Were the millions of feet put through SR3s in the 90s and 00s all scratched on the edge of the image? Why were SR3s the most used S16 cameras for professional use if they were potentially damaging the image area?

Have you personally had a problem shooting S16 with SR3s and the pressure plate pictured, to back up your claim, or are you making stuff up again? I ran a rental house service department with multiple SR3s using those sort of pressure plates for years without issue.

Think about all the cameras where a pressure plate acts on the entire back surface of the film without causing damage, like a Bolex. Or many others where multiple chrome strips act on the back of the film within the image area. The important surface is the gate side.

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8 hours ago, Dom Jaeger said:

Think about it: why do you think it’s OK for the centre piece to push against the back of the film in the middle of the image area but a side rail that might slightly extend into it is not OK? 

Well the sides of the spring loaded pressure plate deal with most of the force. The center section has extremely light pressure on the film. 

8 hours ago, Dom Jaeger said:

Have you personally had a problem shooting S16 with SR3s and the pressure plate pictured, to back up your claim, or are you making stuff up again? I ran a rental house service department with multiple SR3s using those sort of pressure plates for years without issue.

Honestly, I don't care if people reported the problems 20 years ago when the cameras were new and always maintained well. These cameras are not new and are not being maintained to the level they were back then. So sure, Arri in their infinite (not really) wisdom, may have figured that the gap was sufficient to never damage the film. Mind you, the guy who literally invented the super 16mm format, didn't feel the same way. So yea, I trust him over Arri's design. Not saying it's better, just saying it logically makes more sense. 

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Thank you all for your answers. The previous owner of my SR2 told me that he used the (normal) SR2 mags for shooting S16 without any modifications and never had any problems.. What is your opinion about that? 🙂

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16 hours ago, Tyler Purcell said:

On a SUPER 16mm magazine, one side rail will be half the size of the other. Thus not touching image area on the film. 

So this statement is false, right? You have never actually seen a Super 16 SR2 or SR3 mag like this, because they don’t exist. 

4 hours ago, Tyler Purcell said:

Honestly, I don't care if people reported the problems 20 years ago when the cameras were new and always maintained well. These cameras are not new and are not being maintained to the level they were back then. So sure, Arri in their infinite (not really) wisdom, may have figured that the gap was sufficient to never damage the film. Mind you, the guy who literally invented the super 16mm format, didn't feel the same way. So yea, I trust him over Arri's design. Not saying it's better, just saying it logically makes more sense. 

This whole statement makes no sense. But basically what you’re saying is no, you have no personal experience with the issue you’re bringing up.

So back to the point - there is no such thing as a Super 16 pressure plate for any Arri 16SR series magazine, and the system works fine. 

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57 minutes ago, Deniz Cooper said:

Thank you all for your answers. The previous owner of my SR2 told me that he used the (normal) SR2 mags for shooting S16 without any modifications and never had any problems.. What is your opinion about that? 🙂

It’s possible the previous owner never noticed any issues, perhaps he only shot a few rolls of S16. Perhaps he just wanted to sell you the camera.

The places that come in contact with the emulsion side in the expanded S16 area may not always scratch the film or may only lightly scuff it. But over time, it’s pretty likely you’ll get some sort of damage. It may not be too important to you, or these days you could possibly remove defects in post. Give it a go and see.

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9 hours ago, Dom Jaeger said:

So back to the point - there is no such thing as a Super 16 pressure plate for any Arri 16SR series magazine, and the system works fine. 

That is accurate. They didn't feel they needed to re-machine anything. Doesn't mean it's the right way to do things. The gate rails and sprockets are different tho, that's what compensates for that wider rail. 

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