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Arri 35-III Light Leak?


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#1 John Jaquish

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Posted 03 July 2015 - 11:43 AM

Just finished shooting a film for which we used a 35-III for a few shots. We got an HD transfer on the negative, and the shots we used this camera for, it seems there could be some sort of light leak. What I see on the image is an "imprint" of the pressure plate, which increases in intensity if there's any light source flaring the lens, which makes me believe the "leak" is coming from the lens, but something's causing it to bounce around or reflect inside the camera. 

 

Trying to figure out what could possibly be causing this, whether it's somehow user error; or if mechanical, if it could be an easy fix, or something more deadly.

 

Any thoughts would be greatly appreciated.


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#2 John Jaquish

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Posted 03 July 2015 - 12:26 PM

A little more information: I'm looking at the pressure plate, and the surface of the "ridges" seems to have the black paint worn off, leaving a shiny metal surface at those areas, being the exact "ghost" image I'm getting on the exposed film. Could simply re-painting that surface a matte black fix or at least mollify the issue?


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#3 Satsuki Murashige

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Posted 03 July 2015 - 03:58 PM

Do you have any frames you can share of the light leak? That would help a lot in diagnosing the problem.
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#4 John Jaquish

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Posted 03 July 2015 - 04:51 PM

Do you have any frames you can share of the light leak? That would help a lot in diagnosing the problem.

 

Sure thing. This isn't the best still in general, but one that represents the issue (there was light flaring the lens on this frame). We got a flat scan of the film (we shot on b&w film, by the way), and I adjusted the image slightly to exaggerate the issue. Most evident is the horizontal line running across the bottom ~third, and similarly along the top third. Less obvious, there's also a series of smaller horizontal lines running along the whole right edge of the image. Again, these lines mirror the surface of the pressure plate. The "ghost image" pretty much disappears as light no longer is flaring the lens. (For what it's worth, the blotch on the actor's right cheek seems to be some chemical or emulsion artifact unrelated to the issue; it just happened to show up on this particular frame).

 

This is of course a very low-key lighting scenario, though the issue is also vaguely present in high-key lighting (e.g. daylight exteriors). 

 

still copy.jpg


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#5 Satsuki Murashige

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Posted 03 July 2015 - 06:17 PM

Hm, never seen that before. It doesn't look like gate flare, which you would get on the edges of the frame from a specular light source just outside of the frame. From what you describe, it certainly could be the pressure plate. Hopefully, one of our resident film technicians can weigh in and tell you how to repair it.
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#6 John Jaquish

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Posted 04 July 2015 - 09:10 AM

Thank you though, Satsuki.

 

I'm also wondering if the lack of an anti-halation backing on the b&w film exacerbates the issue.


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#7 Simon Wyss

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Posted 04 July 2015 - 10:15 AM

Need not be the pressure plate, inspect the edges of the aperture. These mustn’t be shiny. To me it looks as if you’d have the dreaded ghost frame. A black felt marker will help.


Edited by Simon Wyss, 04 July 2015 - 10:16 AM.

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#8 John Jaquish

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Posted 04 July 2015 - 10:34 AM

Need not be the pressure plate, inspect the edges of the aperture. These mustn’t be shiny. To me it looks as if you’d have the dreaded ghost frame. A black felt marker will help.

 

Thanks, Simon. The ridges on the pressure plate mentioned above are indeed shiny. The edges of the aperture are not on the shutter side of the aperture, though are somewhat shiny on the pressure plate side, as they have similar "ridges" where it seems the black paint has rubbed off.

 

Would I simply use a black Sharpie on these areas?


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#9 evanwalsh

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Posted 04 July 2015 - 10:40 AM

I know its a bit different but I have a still camera that has light leaks and when I don't tape it up enough I will get an imprint of the pressure plate in some of my photos. A photo repair place suggested it could also be caused by the shutter not fully closing causing the ghosting/refleactions in my photos. Did you test the sync of the movement and the shutter as possible cause?


Edited by evanwalsh, 04 July 2015 - 10:50 AM.

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#10 John Jaquish

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Posted 04 July 2015 - 12:05 PM

I know its a bit different but I have a still camera that has light leaks and when I don't tape it up enough I will get an imprint of the pressure plate in some of my photos. A photo repair place suggested it could also be caused by the shutter not fully closing causing the ghosting/refleactions in my photos. Did you test the sync of the movement and the shutter as possible cause?


I have not, though seems reasonable. Do you know how I'd test that?

One other thing I noticed is that the metal frame for the GG is missing (ie the one glued to the glass, that you would pull to remove the GG). Not sure if that would cause any sort of light leak, but replacing it seems to seal it up a bit better.
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#11 evanwalsh

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Posted 04 July 2015 - 12:41 PM

You draw a squiggly line down a length of film with a sharpie, and inch it through the camera to see if the film is held in place when the shutter is open, if you see that the film is not held stationary when the shutter is open, then the shutter and movement are out of sync. This would also cause a verticle streaking in the footage which doesnt seem to be the case in your framegrab, but who knows.

 

When I see the pressure plate reflections in my stills they usually have a slight horizontal streak in the center of the frame and usually have a burned right edge, made me think it could be similar.


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#12 Simon Wyss

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Posted 05 July 2015 - 01:56 AM

Ooh, John, the ground glass is a light diffusor par excellence. I think you hit on the failure. The GG surfaces perpendicular to the light axis should of course be covered. What you can do to further encircle the culprit: Compare the effect between long focal lengths and wide-angle lenses. Stray light is more of a problem with wide angles.


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#13 John Jaquish

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Posted 06 July 2015 - 07:04 AM

You draw a squiggly line down a length of film with a sharpie, and inch it through the camera to see if the film is held in place when the shutter is open, if you see that the film is not held stationary when the shutter is open, then the shutter and movement are out of sync. This would also cause a verticle streaking in the footage which doesnt seem to be the case in your framegrab, but who knows.

 

When I see the pressure plate reflections in my stills they usually have a slight horizontal streak in the center of the frame and usually have a burned right edge, made me think it could be similar.

 

Thanks, Evan. I'll try the sync test either way and see if I come up with anything. 

 

Ooh, John, the ground glass is a light diffusor par excellence. I think you hit on the failure. The GG surfaces perpendicular to the light axis should of course be covered. What you can do to further encircle the culprit: Compare the effect between long focal lengths and wide-angle lenses. Stray light is more of a problem with wide angles.

 

Thanks, Simon. With a new GG, it's still not entirely sealed, though certainly more so than with the previous one. I have noticed the issue seemingly independently of lens focal length (in fact, we have a couple of zoom shots where it's present throughout the zoom range). Would it still be a good idea to try blacking out the pressure plate with a felt marker?

 

I suppose I'll have to run some film tests for these adjustments.


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#14 Simon Wyss

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Posted 06 July 2015 - 09:02 AM

Yes, everything near the film. I presume you’re aware of that the ARRIFLEX don’t have focal-plane shutters. The mirrored shutter stands rather a bit away from the aperture and this the more the nearer we look at the right side of the aperture. Deflection upwards, over the shorter image side length was introduced with the Caméflex in 1946, the Camerette a year later, respectively. Arnold & Richter could adapt that design twenty years later when the French patent had elapsed.

 

The reflex shutters don’t really shut entirely, an unsolved problem not with shooting but for the times the film is not transported. With the early ARRIFLEX non used turret ports must be covered and or the lenses not in use capped. Internal stray light can come from the ground glass (baffles grid before it), from the shutter rims, and more parts. A dull black paint should cover everything nonfunctional between lens and film, and the pressure plate.


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#15 Charlie Peich

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Posted 06 July 2015 - 12:35 PM

Greetings John!

 

John, from looking at your frame grab, I can tell you were shooting with a 35-III version 3 camera. That was the last version of the 35-III. It was the 35-III that is guaranteed go to 130fps with out worrying about long- term damage to the motor’s armature cage under high centrifugal forces.

 

Yes, the 2 horizontal light lines are a reflection from the 2 chrome bars on the pressure pad on the gate. The 35-III v3 was the only version that had the 2 chrome bars on the pressure plate.

 

This model also had the ‘washboard’ film guide (aperture plate), and gate with the pressure pad.

 

“Less obvious, there's also a series of smaller horizontal lines running along the whole right edge of the image. Again, these lines mirror the surface of the pressure plate.”

 

Those lines are the edges of the ‘washboard’ gate. Arri had this to say about this design:

 

A fixed gap film channel keeps the film in an optimal position between the film gate and the film guide. The special finish of the filmgate guarantees minimum friction at all filming speeds.’

 

35-III version 3 gate:

 

IMG_4093_zpsn8k15kng.jpg

 

 

‘though are somewhat shiny on the pressure plate side, as they have similar "ridges" where it seems the black paint has rubbed off.’

 

The valleys between the raised ridges seem to be painted black, but I can’t see how the paint would have been removed or worn down, over cleaning possibly. Would need to see more pics of your gate/pressure pad or film guide showing the worn spots.

 

However, your statement told me the cause of your problem right away.....

(I’m surprised you didn’t pick up on this, Simon)

 

"I'm also wondering if the lack of an anti-halation backing on the b&w film exacerbates the issue."

 

I have to ask, light heartily, why were you shooting film with no anti-halation backing in an Arri 35-III? All the late model 35mm cameras, along with Arri, were cameras designed for film WITH anti-halation backing. They had shiny gates/pressure pads, or parts on the pressure pad that are shiny.

 

Was there an effect you were trying to achieve because of the lack of the anti-halation layer? Usually, when shooting without the anti-halation backing, one would want the effect of the light bouncing off the shiny pressure plate back onto to film to create a 'halo effect' around the subject. I don't think there is a filter that can replicate that look.

 

Did you shoot any film with anti-halation backing with this camera for your project? If so, was it ok?

 

 

Anti-halation Backing:  The anti-halation backing is the dark coating applied to the back of the base. It is there to prevent light from passing through the film, reflecting off of the pressure plate, and then passing through the film again, causing a flare or flash in the image or a double exposure.

 

 

Kodak sez….

Light penetrating the emulsion of a film can reflect from the base-emulsion interface back into the emulsion, causing a secondary exposure around images of bright objects. This secondary image (halation) causes an undesirable reduction in the sharpness of the image and some light scattering. An antihalation layer, a dark coating on or in the film base, will absorb and minimize this reflection.

 

In the mid 1990's, commercial shooters re-discovered Infrared film. While Infrared film (RIP Kodak Infrared film) had its own unique characteristics, it had 1 thing in common with your film, no Anti-Halation backing

 

Clairmont Camera met the demand for cameras that were able to handle Infrared film by making black pressure plates to solve the 'halation' problem. They wrote a Tech article about this for their site: 

 

There can be problems with certain cameras using infrared film. The black & white infrared film is very translucent and the color infrared film, though less translucent, is still a problem. Because of this, the camera must have a black pressure plate or the light will pass through the film and reflect back causing an exposure problem and making the photographic impression of the shiny bars on the pressure plate. Arriflex 2C's and Mitchell cameras do not have this problem since they do not have chrome pressure plates. All the modern cameras have chrome pressure plates. Clairmont Camera can provide black pressure plates for the Arri 435, Arri 3's, Moviecam and Eyemo cameras and we're working to get black pressure plates for all other cameras. 

 

http://www.clairmont.com/tech_tips/filming_ir.html

 

 

A II-C pressure plate...

 

IMG_3149_zpseiyr445z.jpg

 

 

 

As you can see the pressure plate is solid black, so no light would bounce back (Ok, there’s a small scratch in the black paint on this pressure plate, but this camera has only run film with Anti-halation backing. This is also a gate pic from an Arri II-A, but the II-C gate is the same). Or, you could remove the black paint and have a shiny pressure plate to create the halo effect.

 

The fact that the metal tab on the G.G. is missing, is not good. Not only for light piping as Simon explained, but also for proper seating of the G.G. in the metal holder on the camera. The spring loaded retainer is set for the thickness of the metal plate with tab. Your G.G may not have been seated properly (effecting left to right composition). Remove the aperture plate/film guide, and you can gently push the defective G.G. out. Replace that or repair it.

 

As for light coming from the lens and bouncing around causing reflections and fogging the film, my 1st thought would be from the ground glass surface facing the gate.

 

Arri fought this problem since the inception of their spinning mirror shutter for reflex viewing. It has to do with the proximity of the G.G. to the aperture. The 35-III was the next generation from the 2-C, but the problem was still there, somewhat lessened, lack of 3 lens turret on the 2-C, but still a possibility. The 435 eliminated it, as did Arri’s 35 BL series of cameras.

 

Arri solved this light scattering problem with ‘light baffles’ on the Arri I, II, II-A, II-B, II-C and 35-III. They claimed it eliminated the problem.

 

Please take a moment to read this article linked here, page 105. It explains what is going on with the baffles.. middle of the page...

 

http://https://books.google.com/books?id=18Ck5PZX_ZsC&pg=PA105&lpg=PA105&dq=arri+2-c+light+baffles+in+finder&source=bl&ots=uMRytKWX74&sig=tyNLSH5n7ecc-GPFzPMPjK7D6m0&hl=en&sa=X&ei=a02ZVaqnDsWuyASrzYH4Ag&ved=0CCsQ6AEwAw#v=onepage&q=arri%202-c%20light%20baffles%20in%20finder&f=false

 

Up to the 2-C, there are 4 matte black baffles over the G.G…..

(the next 2 pics show the baffles reflected into the closed shutter)

 

post-44581-0-84256700-1294441373_zpsupm4

 

 

 

 

The 35-III reduced it to 2 baffles (no G.G. in holder).....

 

IMG_20150706_0001_zpsaqekxjyp.jpg

 

 

 

 

But, some opertors hated the 4 baffles on the 2-C, and the 2 baffles on the 35-III…. a distraction for framing while shooting..... waaaaaah. With the rise in popularity of video assist, many questions were asked in video village by the client…’what are those 2 black lines for?? Will they be on my film??’

 

So, some people not understanding what the baffles were for, started pulling them off….’aaaaah, you don’t need them, they just get in the way’ .. etc.

 

Well, they do prevent stray light from scattering and flashing the film. I never shot with a camera with them removed. There was always talk of…. ‘well, in certain conditions’. But no one ever listed those specific conditions. One was kept guessing. (to this day)

 

John, did your 35-III camera have those 2 light baffles removed? If so, that could be part of the problem, especially in low light conditions.

 

All the suggestions given by the other posters in this thread are great, and should be checked also.

 

What you should do to trace this problem down is, get the camera and lens you used, recreate the set-up you originally shot with the same lighting and light levels, shoot it with the B&W film without Anti-halation backing and then shoot it with film with Anti-halation backing. Then compare the 2 films. 

 

After looking at your frame grab, I’m still leaning towards the B&W film with NO anti-halation backing as the problem.

 

I would like to know what film you were using. And again, what look were you going for. I’m all for experimenting with different film stocks, love it, and I applaud your efforts going for a different look, I’m sorry you had a problem.

 

Charlie

 

P.S. 

There is another light reflection problem that has a name that I can’t recall. It’s where the light forming the image is reflected off the emulsion back onto the rear element of a fast lens (large rear element) that is close to the aperture, it is then reflected off that rear element back onto the film causing a superimposed ghost image around the original image. Anyone ever hear of that? I think it was Panavision that discovered that phenomena.


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#16 Simon Wyss

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Posted 07 July 2015 - 01:32 AM

There is another light reflection problem that has a name that I can’t recall. It’s where the light forming the image is reflected off the emulsion back onto the rear element of a fast lens (large rear element) that is close to the aperture, it is then reflected off that rear element back onto the film causing a superimposed ghost image around the original image. Anyone ever hear of that? I think it was Panavision that discovered that phenomena.

 

That is known since glass plate photography. In the 19th century already photographers chose coloured glass, smeared lacquers and paint on the plates backside, covered them with black paper or velvet. Anti-halo undercoats are also known since long.

 

I let myself be led by the image in post #4. That is really a mirroring of aperture plate and pressure pad.

 

John, what film is it?


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#17 John Jaquish

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Posted 07 July 2015 - 02:43 PM

Charlie, thank you so much for your detailed response. I was on a shoot yesterday so couldn't get back to you immediately.

 

I'll respond to the points you brought up to the best of my knowledge:

I have to ask, light heartily, why were you shooting film with no anti-halation backing in an Arri 35-III? All the late model 35mm cameras, along with Arri, were cameras designed for film WITH anti-halation backing. They had shiny gates/pressure pads, or parts on the pressure pad that are shiny.

 

Was there an effect you were trying to achieve because of the lack of the anti-halation layer? Usually, when shooting without the anti-halation backing, one would want the effect of the light bouncing off the shiny pressure plate back onto to film to create a 'halo effect' around the subject. I don't think there is a filter that can replicate that look.

 

We were shooting on ORWO N74+ and UN54 black and white film (similar to Kodak Double-X; it's "standard" black and white film, i.e. not infrared film). I should say I'm not certain it completely lacks an anti-halation backing, but understand that if it does, it's less substantial than color film. 

 

We were shooting on black and white film because we wanted the film to be in black and white. We weren't going for any look or effect apart from that. 

 

Although I understand and very much appreciate all the info on the 35-III, I find it hard to believe this camera lacks the capacity to shoot standard black-and-white film. I feel as though there's something else going on here, though I of course could be wrong. For example, our main camera was a 35BL-3. Now that I look at the BL-3 again, it also has chrome "ridges" on the pressure plate, and we had absolutely no issues with that footage with the same film stock (also, our 35-III pressure plate looks identical to the picture you attached -- the "valleys" in the grooves are still black, and I was assuming the chrome on the ridges used to be painted as well, though perhaps not).

 

Further, the 35-III does have the two light baffles, and they are intact.

 

Now that you mention the GG not being seated properly, it seems the shots we got from this camera are also slightly off center horizontally (for example, in that still I posted, I probably had framed the actor more centered). I have now replaced the GG with a proper one, and hoping that was the issue. Of course, I'll need to test the camera again, and it would be a good idea as you mentioned to also test it with some color film.

 

Of course, that'll teach me to shoot with an untested camera; though fortunately, we probably only got three or four shots with this camera for the whole film. The issue with the daylight exterior shots is much more subtle than the still I posted above (and like I said, the issue almost disappears for that shot when light's not flaring the lens).

 

(Also, Evan, I performed the sync test and see no movement of the film while the shutter's open).

 

Thank you all for your input and please let me know if you have further ideas based on this updated info.


Edited by John Jaquish, 07 July 2015 - 02:44 PM.

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#18 Simon Wyss

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Posted 08 July 2015 - 01:30 AM

Black-and-white negative films have a coloured base, i. e. the acetate plastic is dyed in the mass. Kodak films typically have a base density of log 0.23 which cuts away 36 percent of the excess light coming from the photographic layer. After that diminuation light reflected by the back surface of the base or shiny elements is again diminished by the base before it hits the light sensitive layer. Color films have a colourless base and a thin soot-blackened gelatine back layer as anti-halo measure.

 

I am as surprised by that impression as you. Inasmuch I can excerpt from the N 74 data sheet its base density is log 0.25. That amounts to almost 40 percent of light attenuation. One would have to inquire the exact value with Filmotec or make a measurement on a non-developed and fixed snippet.

 

But it may be the best to show the issue Arnold & Richter now.


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#19 Rudy Velez Jr

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Posted 03 August 2015 - 11:00 AM

very interesting conversation here.

@JohnJaquish big fan of your B&W cinematography, I can't wait to see what you have been working on. Hopefully you can find some technicians to service your 35 III.  


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#20 John Jaquish

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Posted 03 August 2015 - 11:25 AM

Thank you much for the kind words, Rudy.

 

Incidentally, still haven't had the chance to test the camera with the GG switched. Will post an update when I do.

very interesting conversation here.

@JohnJaquish big fan of your B&W cinematography, I can't wait to see what you have been working on. Hopefully you can find some technicians to service your 35 III.  


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