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Arri IIc flare problem


GeorgeSelinsky

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Hi folks,

 

While doing some routine maintenance on my IIc, I decided I'd try to address the shutter flare problem as best as I can again.

 

Here is the problem with the flare:

 

Real Video for 56k Modems

 

Real Video for Broadband

 

Windows Media Player for 56k Modems

 

Windows Media Player for Broadband

 

When you click on these, for some reason an empty window opens up, just close it after you're done with the video. Thanks!

 

As you can see, even diffused light from a window, light from the clouds, and other soft sources cause this flicker. I'm using old Cooke Speed Panchro's. The flare is particularly bad on the 50 and 75mm, which are Speed Pahchro II's. The F-stop doesn't seem to make much of a difference. I've painted the heck out of everything, no improvements.

 

Here is the problem I found in the camera, looking into the lens port at the viewfinder (mirrored off the shutter)

 

Arri-problem2.jpg

 

The baffle next to the red line USED TO bend to the RIGHT of the red line. Now I touched it with a screw driver which bent it to the LEFT side of the line. It won't, however, stand straight. Could this bending baffle be the culprit?

 

Thanks for all advice as always,

 

- G.

Edited by GeorgeSelinsky
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BTW, be sure to also check out the rec.arts.movies.tech newsgroup. I posted the question up there and perhaps some techs will be able to contribute some suggestions too.

 

Incidentally, I have seen this kind of flicker flare in some feature films, noteably in the "French Connection" an instant before the drug runner guy gets shot by Gene Hackman (it cuts just when the flicker starts). Either way my Arri does it way, way too much. I can sense this flicker in many shots but in most cases it's hardly noticeable. When it goes to print, some of it will be buried by the printstock.

 

- G.

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Interesting, George. I experienced a similar problem with a IIc a while back. I used the same 2 lights for the entire shoot and the problem only seemed to occur when the light was coming from a right angle to camera position. Don't know if this mean anything.

 

Would love to know if this is inherent in the camera. I really loved shooting full frame and taking advantage of the full size of the negative.

 

Please let us know what you come up with.

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not sure if what I say will help but here goes.

 

NOTE I only have 2 baffles in place and I don't get flicker - touch wood

 

Close the viewfinder off - check if it continues - 9 times out of 10 ithe light leak comes back from the view finder

Use black electrical tape to cover from the groundglass front - my batteries are dead on my digital (but when they are better I can send you a still) - the best way to see this problem is take the groundglass out of the camera - then have a look through the eyepiece (put a lens on the camera) you will see a mirror of your view from your iris (a sphere) move your eye around and you will see the light leak at the top - this is the most likely cause

The other areas you get light leaks are on the eyepiece (where the little lever opens and shuts the final eyepiece eyelid - the one that can catch your eyelashes

There are other light leak areas in the camera body - the attachment for the old matt box at the top had dodgy screws and it is a good idea to tape it off again

There is an old sound connector unit thing next to the old matt box holder that also needs taping up

If you have a 2cVB check the paper on the shutter markings is not coming loose - it can do weird things

Check the spring system that mounts the eyepiece door onto the body if it makes any noise it is too loose and needs to be tightened - easy just use a flat piece of something to fit in and bend the levers down about 0.5mm

If you have a solid PL mount it should be OK

 

Something else is too shine a torch down a roll of card at a lens and open the body and check if you are getting light leaks around the PL connections - very rare

 

Also shine a torch down the eyepiece and check from the mag load hole for leaks

 

thanks

 

R

Edited by Rolfe Klement
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Some more stills to illustrate the problem...

 

I stuck my digital camera into the eyepiece of the IIc (I'm surprised it was able to get an image from that) and took some snaps (with great difficulty)

 

I had a white exposed 60 watt halogen bulb standing before the camera. I tried panning it left and right about 30 degrees or so. I was about a half to 2/3rds of a meter away from the light source.

 

This first image is of the 50mm. This is what I get when the shutter is open, with film in the gate - this orangy flare (which means it's being reflected from the filmstock):

 

ArriFlare50mm1.jpg

 

When the camera is pointed a few degrees left, this is what I get - a white flare:

 

ArriFlare50mm3.jpg

 

Then, when the camera is pointed to the right a few degrees, this white ghost appears on the right side, the baffles do not show any light flaring:

 

ArriFlare50mm2.jpg

 

Finally, when the camera's shutter is closed (mirror in place), when the camera is panned to the left there is a flaring by two of the baffles:

 

ArriFlare50mm4.jpg

 

With the 25mm, I get a similar effect when the above is done, only different baffles get hit.

 

ArriFlare25mm1.jpg

 

No matte box was on the camera for this test, and it's important to indicate that the degree of rotation was not significant enough to have the matte box affect the result.

 

Rolfe: Thanks for your advice! My camera is not the variable shutter model.

 

- George.

Edited by GeorgeSelinsky
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What are those baffles for exactly? I think it was explained to me once, but I don't recall and I've got the exact same in my Arri IIB. What mystifies me is that it's a flicker and not a constant fogging. I'm at the day job and I don't have the Arri in front of me, but that is a major clue to me- that between one frame and another this flare/ fogging effect decreases and increases in intensity. I don't think that a glint off the baffle would do that, if that were so it would be consistent from one frame to the next.

Edited by Webster C
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Something else is too shine a torch down a roll of card at a lens and open the body and check if you are getting light leaks around the PL connections - very rare

 

Also shine a torch down the eyepiece and check from the mag load hole for leaks

 

What about doing this while slowly turning the mechanism as to have the shutter round before the gate...

Edited by laurent.a
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Mmmm - a couple more ideas

 

Does the problem go away when you shut of the eyepiece?

Does the problem occur with newer lenses (like the Zeiss Ultras etc)

 

This might be obvious but is the groundglass in the right way - in the z direction.

It almost looks like the baffles have different depths.

Are the baffles deformed on the z axis as well

It is quite easy to get a groundglass with baffles (at least in LA) have you tried replacing just the baffle unit

 

The basic problem is to figure out if the eyepiece and baffles are actually causing the issue. If you take the path the 3 light sources take - light from the lens, light from outside and light from the eyepiece - and each of their associated routes then check for faults.

 

It could even be flashing in the mag...

 

the primary job is to figure out where and what is causing the addintional unexpected light exposure on the film

 

Have you had a chance to run any tests - cause if the baffles look weird - then they look weird but you don't want to spend time fixing it if it is not actually causing issues on the film

 

thanks

 

R

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This is a shot that has been scanned and stabilized, sorry the file is so large but you really can't see the problem at a lower rez. It's in the upper right corner around the kick light source. This was shot with my Arri IIB in Academy, not full ap (standard Arri mnt. Schneider 35mm lens). It's a very subtle flicker.

10MB Quicktime

 

Because it's a consistent flicker, my thinking is that it's happening on one 'taking' section of the mirrored shutter and not the other. The arri shutter has two blades, as you can see in this sequence below- I rotated the inching knob through a full revolution of the shutter. I am doubtful that it has anything to do with the baffle.

 

DSCN3537.jpg

DSCN3538.jpg

DSCN3539.jpg

DSCN3540.jpg

DSCN3542.jpg

DSCN3543.jpg

DSCN3544.jpg

 

George, have you tried contacting Arri? I've sent them emails in the past regarding projection equipment and gotten very helpful, timely responses.

 

-Webster Colcord

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Looks like two problems to me. But first I agree that a trip to Arri would be great. The first problem: in the test movies it looks as though they are lens flares from the lighting sources. Even soft lighting sources like the sky or the window. Older lenses don't have the anti reflective coatings a newer lens has. Do you get these flares using newer lenses? The one shot where the girls walk to the right and the camera pans and dollys to the right, there is a flare from the window. As you pan away the flare goes away but then comes back! Like light is hitting the lens from somewhere else. Is the matte box correctly attached and in good shape? Sometimes if the matte box is not attached properly you can get a flare or light bouncing off any glass filter in the matte box itself. But I don't think that is the problem here. The one shot where the girl is eating dinner the warm tablelamp is the obvious source of the flare. The light is just bouncing around the elements in an older lens. Same with the guy looking down at the camera. The light on the cieling is the cause of the flare.

 

Now the flicker is another issue. Though a trip to Arri is warranted to get it checked out I was wondering why it is flickering (duh). It seems as if during the movement the flare is reduced or eliminated. Is there something during the rotation of the mirror that blocks the light leak or flare? or could it be part of the the old lens coating issue. I don't have a suggetion on this one.

 

Please post your solutions when they are found.

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I've seen this is in some 2Cs before too. Because the camera doesn't have a focal plane shutter, it is possible to have a leak somewhere in the chamber (you don't use this camera for stop motion photography). A slight out of synch shutter could create/amplify the problem, or depending of the angle from or where some flares are projected by different lenses, some light finds it's way to the film gate.

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George,

 

Does the problem happen when you shoot with a particular lens or different lenses?

 

The only lenses I have been able to put on it are the Cooke Speed Panchro's which I own. The problem exists with all three lenses, the 25mm, 50mm, and 75mm. Unfortunately it's beyond my means right now to take the camera to repair (Arri, incidentally, will not deal with a IIc, they consider it to be antiquated).

 

- G.

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Now the flicker is another issue. Though a trip to Arri is warranted to get it checked out I was wondering why it is flickering (duh). It seems as if during the movement the flare is reduced or eliminated. Is there something during the rotation of the mirror that blocks the light leak or flare? or could it be part of the the old lens coating issue. I don't have a suggetion on this one.

 

Please post your solutions when they are found.

 

The flare itself I am not even so confused by, that is to be expected with old glass. The lenses, incidentally, were always shielded by the matte box. The instance where the flare disappears and reappears was indeed an anomaly - there wasn't a second source and it's happened like that before in another shot, too.

 

The flicker is what really bothers me because it is extremely unnatural looking.

 

- G.

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Since it happens with all your lenses, I think it's very unlikely to be a lens problem. I thought maybe one of your lenses was leaking, but not on all three.

 

The 'flaring' in your media file doesn't look like typical lens flaring to me. It looks like it's directly related the flicker issue.

 

A friend of mine has a 2B with the exact same problem.

 

Did you see Adam Frisch's post from Oct: http://www.cinematography.com/forum2004/in...604entry20604

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I have somewhat limited experience with the 2C (and none with 2B) but have used it in the past with strongly backlit situations, no special problems.

 

It is true however, that any internal bounce-off-the-glass (the reason for those baffles in the first place) issues will be more likely to come from longer fl lenses as the cone of light is larger.

 

-Sam

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I only have 2 baffles - to hold the glass in place and have never had problems (touch wood) even shooting into HMI's

 

Here is an image of how I do the electrical tape cover on my camera - standard black tape - Joel @ Otto N taught me

 

front.jpg

 

Note - only 2 baffles

 

It is weird seeing how beat up my camera is - when you look at photos of it :D

 

I would be interested to know what the issue is - George - have you called Joel at Otto N?

 

thanks

 

R

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I'm surprised you have the baffles in your 2C. In the old days, we used to rip them out with a needle nose pliers. They really don't do anything but make vertical lines in the finder. Note that none of the newer designs have them.

 

 

 

-- J.S.

Edited by John Sprung
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From the look of the flicker, I'd guess that it's coming from one of the two blades of the Arri shutter, but not the other. Can you look at the film frame by frame to see if the flare is on every other frame? It doesn't look at all like a travel ghost, it seems to be happening with the film stationary in the gate. My guess is a shiny place on one edge of a shutter blade reflecting bright areas of the frame into other parts of the frame during the passage of the blade edge over the aperture.

 

One thing to test would be to make a short piece -- a foot or two -- of ground film. Wash the emulsion and backing off to get clear plastic, then make a sort of ground glass like surface on one side by rubbing it with a wet paste of kitchen cleanser. Put this in the gate, but don't close it. Look at the image on the ground film -- difficult to do, I know -- while you slowly inch the camera. Set up a black BG with a single hot practical in frame in various places if you don't see the flare at first.

 

 

 

-- J.S.

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This is the quote from that Oct thread-

 

What's much more serious on the 2C's is their internal flaring. For some reason, incoming hotspots bounce off the mirror at certain angles and flicker the film. It can be very serious. If I recall the tests I saw correctly, it's mainly on the right side. I hear this is due to the removals of the baffles across the ground glass. It was particualarly visible on the SL Cine lightweight rebuilds. So however tempting - don't remove the baffles across the ground glass!

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Guest Sean McVeigh
From the look of the flicker, I'd guess that it's coming from one of the two blades of the Arri shutter, but not the other.

 

I think John is on the right track. It's definitely something assymetrical over one half of the mirror-shutter assembly. If the shutter were just out of sync, you'd see it in both frames. I'd also say that the bent baffles are a bit disconcerting... it's possible that an internal reflection is playing off of one of the baffle blades, but since it's clearly prominent every other frame, this may only be half of the problem.

Has the camera always had this flicker problem? Have you replaced the mirror shutter at all? If it's slightly out of sync, this could simply be magnifying an pre-existing problem.

I can't recall what all is on the mirror shutter shaft, but I'd have a look at everything on that shaft/hub. Since it looks like it repeats on every full revolution, it could just be a shiney screw head holding the mirror in place, or a scratch on the mirror mounting hub.

Rolfe's idea to tape the ground glass may at least eliminate that as a potential culprit.

 

Eliminate variables.

 

Also, John's idea to set up a sort of second ground glass using clear film in the gate is a good idea. You could even try painting the lens with a laser pointer or something to trace the light-path inside the camera.

 

-Sean

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