Arri IIA Shutter

[Frank Cook]

I just bought an Arri 35 IIA and need to identify the shutter angle. It should be 120 degree, but it could have been upgraded at some point to 180 degree. How do I tell the difference?

[Christian Appelt]

Frank, all Arri 2A models had an 180 degree shutter. Only the Arri I+II had the smaller shutter opening.

 

You can make sure that your camera is a IIA by removing the small plastic cover over the claw drive - Arri II has a round disk, IIA and later models have a eccentric (heart-shaped) disk.

[Dan Goulder]

You can make sure that your camera is a IIA by removing the small plastic cover over the claw drive - Arri II has a round disk, IIA and later models have a eccentric (heart-shaped) disk.

Actually, the movement wasn't changed until the 2B.

[Leo Anthony Vale]

Actually, the movement wasn't changed until the 2B.

 

Christian is correct.

The 35II is frequently misidentified as the IIA.

Perhaps because the differences between the IIA and IIB are so minimal.

 

Another difference between the II and IIA is that the II has a single set of wings that open the mount blades on all three lens mounts, while the IIA and all later models have a set on each of the mounts.

[Frank Cook]

Christian is correct.

The 35II is frequently misidentified as the IIA.

Perhaps because the differences between the IIA and IIB are so minimal.

 

Another difference between the II and IIA is that the II has a single set of wings that open the mount blades on all three lens mounts, while the IIA and all later models have a set on each of the mounts.

[Dan Goulder]

Christian is correct.

The 35II is frequently misidentified as the IIA.

Perhaps because the differences between the IIA and IIB are so minimal.

Sorry Leo, but I'm standing my ground on this one. The difference between the II and IIA is the 180 degree shutter. The claw mechanism was changed on the 2B, and is identical on the 2C.

[Frank Cook]

Christian is correct.

The 35II is frequently misidentified as the IIA.

Perhaps because the differences between the IIA and IIB are so minimal.

 

Another difference between the II and IIA is that the II has a single set of wings that open the mount blades on all three lens mounts, while the IIA and all later models have a set on each of the mounts.

 

I'm pretty sure this is a IIA because the serial number starts with Nr. I found a camera that is known to be a IIa that also has that prefix. Thanks for the info on the wings, this camera has them for each lens.

 

I am in question about the shutter angle because Visual Products says on their site that the Arri 35 IIA has a 120 degree shutter. I person I bought the camera from thought this camera has a 180 shutter, but wasn't sure. The mirror in this camera is a "butterfly" shape with four mirror faces. I should be able to measure the mirror and determine the angle, but I need the specs. I have had NO luck finding this information on the web. If someone has an Arri with the 180 degree shutter they could measure the widest part of the mirror and post it.

 

Because these cameras are upgraded and modified over the years, I don't want to assume anything.

[Christian Appelt]

D. Goulder wrote:

Sorry Leo, but I'm standing my ground on this one. The difference between the II and IIA is the 180 degree shutter. The claw mechanism was changed on the 2B, and is identical on the 2C.

 

I have scanned an article taken from FILM TECHNIKUM, a German film technology paper, printed in June 1954, page 154:

The text is in German, I will translate a few passages (some people on this forum speak German, so they can correct my amateur translation if necessary):

 

 

 

 

"Image steadiness had not been sufficient for all applications of the Arriflex, a price that had to be paid for the comfort of reflex viewing. The engineering departement of Arnold & Richter, Munich, have tried to improve on this to encourage the use of Arriflex for a wider field of applications.

They have succeeded in this by creating both a new 180-degree mirror shutter and a new film transport/pulldown system. This has resulted in 50% more exposure time, excellent steadiness and absence of any excess vibration."

 

On the photo, you can see the then-new heart-shaped claw drive so familiar to us Arrificionados ;).

 

In another issue of FILM TECHNIKUM and the other trade paper KINOTECHNIK, there is an advertisement by Arri for "the new model IIA camera with improved 180-degree-shutter and superior steadiness". Could not scan that one because the bound volume is very brittle, I'll scan another one next time I have access to a single magazine.

 

There is definitely no difference between Arri IIA, B, and C regarding the claw mechanism. My IIA no. 3962 has 180 degrees too. In the past, some people have tried to resell ARRI II models as IIA, maybe this is where the myth came from... :)

Edited April 24, 2007 by Christian Appelt

[Leo Anthony Vale]

I am in question about the shutter angle because Visual Products says on their site that the Arri 35 IIA has a 120 degree shutter. I person I bought the camera from thought this camera has a 180 shutter, but wasn't sure. The mirror in this camera is a "butterfly" shape with four mirror faces. I should be able to measure the mirror and determine the angle, but I need the specs. I have had NO luck finding this information on the web. If someone has an Arri with the 180 degree shutter they could measure the widest part of the mirror and post it.

 

The 1953 edition of the AC handbook states that the Arriflex 35 Model 2 has a shutter angle of 120 degrees.

 

The 1956 edition states that the Arriflex 35 Model IIA has a shutter angle of 180 degrees.

 

Under TYPE OF DRIVE it is stated that the 2's "tachometer registers speeds to 40 frames per second with 30 V batteries". I've tried driving one with a 16V, it couldn't get past 8 or 12 fps. But a CP Xtal motor ran it at 24 fps.

 

The IIA has "Tachometer registers speeds to 50 frames per second with 16 V batteries."

 

Since the AC handbooks were printed while thus models were being manufactured I give them more credence than a contemporary web site which is 50 years after the fact.

 

Chek your tach and the number of lens locks on your camera to see if it's a 2 or a IIA.

[Christian Appelt]

Just wanted to add that the article's headline says Arriflex with new Mirror Shutter

Note the picture, here you can see the then-new heart-shaped claw drive so familiar to us Arrificionados ;).

[Frank Cook]

Now were're getting somewhere. Christian, since you have an Arri IIA with the 180 shutter, could you measure the shutter opening (at widest point)? The opening is a different width for 120 than it is for 180 so if I have a measurement on a shutter that is a known opening, I can then measure mine and know what I have for sure. I'm getting great information here on early Arriflex models, but since the shutter opening controls exposer, it would be very expensive to ruin film guessing the shutter size wrong.

 

I suspect this camera has been modified over the years, so I just want a way to verify things.

[Dan Goulder]

There is definitely no difference between Arri IIA, B, and C regarding the claw mechanism. My IIA no. 3962 has 180 degrees too. In the past, some people have tried to resell ARRI II models as IIA, maybe this is where the myth came from... :)

Since two different Arri techs I know claim otherwise, we're probably just going to go around in circles on this. One of them, at Cinematechnic, has a website which spells out the differences between the different models quite thoroughly. If you still think they've got it wrong, you should tell them.

[Frank Cook]

Since two different Arri techs I know claim otherwise, we're probably just going to go around in circles on this. One of them, at Cinematechnic, has a website which spells out the differences between the different models quite thoroughly. If you still think they've got it wrong, you should tell them.

I never thought I would stir up this much disscusion of which camera has what mirror! Somehow I thought there would be a way to just look at the mirror and know what I have. Ha! Anyway, I guess I can always use measurements and math. Maybe I'll just shoot a little footage exposed for the 180 mirror and see if it comes out too dark.

 

Boy, it seems like there should be some way to look at the mirror and determine the shutter degrees.

[Dan Goulder]

I never thought I would stir up this much disscusion of which camera has what mirror!

Welcome to Cinematography.com! I was just trying to help you identify the camera. I know Christian also means to be helpful, and we can respectfully disagree. You might find the Cinematechnic web site interesting, especially concerning the history of Arriflex cameras, and if you send Jorge an e-mail with any questions, he'll probably answer you within a couple of days.

[Frank Cook]

I went to cinematechnic.com (not my first time) to contact Jorge. To my surprize, he said he has not seen the Arri IIA. He also thought it would be either a 180 or 165 degree shutter. He has not heard of a 120 degree shutter. Probably didn't think of an older shutter from a 35II being a possibility -I'm sure he's a busy guy.

 

The camera looks to be built from other cameras. I ran some dummy film through it and it seems to work great. That's what I bought it for is having a camera that works (it has ugly paint). The two halves of the body look like they came from different cameras. There is a difference in the way they are painted. I think the camera was assembled then painted, but it easy to tell the two sides are different. The door I would guess came from still a different camera.

 

All this leaves still leaves me with the question: Which shutter does it have?

Edited April 25, 2007 by Frank Cook

[Leo Anthony Vale]

Welcome to Cinematography.com! I was just trying to help you identify the camera. I know Christian also means to be helpful, and we can respectfully disagree. You might find the Cinematechnic web site interesting, especially concerning the history of Arriflex cameras, and if you send Jorge an e-mail with any questions, he'll probably answer you within a couple of days.

 

So Frank says that Jorge has never seen a IIA.

 

I don't have the AC Handbook Xeroxes with me today, but the descriptions of the the pulldowns for the 2 and IIA are different, with the IIA described as having a registration effect. This agrees with Christian's article.

 

As to why the principle differences between the IIA and IIB are an upgraded motor and the 480 magazine, you'll have to ask Arri. & that's from 50 years ago.

[Dan Goulder]

So Frank says that Jorge has never seen a IIA.

All this establishes is that no one has ever sent him a 2A for repair. If you're convinced that Cinematechnic, which is an authorized Arri service center, is putting out misleading information on their website, then you should notify them.

[Frank Cook]

All this establishes is that no one has ever sent him a 2A for repair. If you're convinced that Cinematechnic, which is an authorized Arri service center, is putting out misleading information on their website, then you should notify them.

I have only the highest respect for a repairman that says he doesn't know (MUCH better than the guys that will lie and claim to be an expert). I think Jorge gave a good honest answer. Kudos to him. I was surprized that he has not worked on the Arri IIA, but I don't think he tried to mislead me, or give out bad information. Who knows, maybe I'll be able to sent the camera in to Cinematechnic for some upgrades, then Jorge will have his chance to look it over.

[Frank Cook]

Ah ha!!! I have it.

 

I was advise by Tobin that measuring is the only way to identify the shutter. Hmm. They reminded me the 180 degree shutter is half of the area of the shutter. So I looked at the camera and realized all I needed to do was compair the size of blades vs. the opneings. A 180 would have them both the same size. Mine has more mirror, so it is a 120 degree shutter. (There's too much difference to be a 165 degree shutter)

 

Thank guys!

Edited April 26, 2007 by Frank Cook

[Frank Cook]

Up-date: The camera I have turned out to be an Arri Model 1. No wonder I could not find information on the specs that match the camera! I have not done a registration test, but it runs nice and smooth with dummy film, and will pull a full mag. The camera has all matching ID codes inside, even the motor (127).

[John Sprung]

Sorry Leo, but I'm standing my ground on this one. The difference between the II and IIA is the 180 degree shutter. The claw mechanism was changed on the 2B, and is identical on the 2C.

 

The pulldown mechanism and shutter angle would necessarily have been changed at the same time. The pulldown places an upper limit on the possible shutter angles that a camera can use, because the shutter can only be open when the film isn't moving. Otherwise, you get severe vertical streaking of highlights. Fixed shutters are generally designed for the largest opening the pulldown will allow. If the simple bell crank were capable of supporting a 180 degree shutter angle, they would have used that angle from the beginning. Certainly they wouldn't have used such a very small angle as 120 unless the pulldown forced the decision.

 

It's possible that they may have tested prototypes of the new cardioid cam pulldown using the old 120 degree shutter, but fitting a 180 degree shutter to a camera with the old bell crank movement simply won't work.

 

 

-- J.S.

[Dan Goulder]

The pulldown mechanism and shutter angle would necessarily have been changed at the same time. The pulldown places an upper limit on the possible shutter angles that a camera can use, because the shutter can only be open when the film isn't moving. Otherwise, you get severe vertical streaking of highlights. Fixed shutters are generally designed for the largest opening the pulldown will allow. If the simple bell crank were capable of supporting a 180 degree shutter angle, they would have used that angle from the beginning. Certainly they wouldn't have used such a very small angle as 120 unless the pulldown forced the decision.

 

It's possible that they may have tested prototypes of the new cardioid cam pulldown using the old 120 degree shutter, but fitting a 180 degree shutter to a camera with the old bell crank movement simply won't work.

-- J.S.

Your point is questionable, as both movements are designed to advance the exact same amount of film in the exact same amount of time, regardless of the angle of the shutter.

[John Sprung]

Your point is questionable, as both movements are designed to advance the exact same amount of film in the exact same amount of time, regardless of the angle of the shutter.

Though you may run different cameras at the same number of frames per second, the percentage of the cycle time spent pulling down and the percentage spent exposing the film can vary quite a bit. The simple bell crank of the model I gives you a sinusoidal vertical motion. The cardioid cam of the II-A produces the "dwell" at the top and bottom of the stroke, which adds to the amount of time that the film is stationary.

 

Both cameras have a one frame per revolution inching knob, so you can do a little experiment: put some white camera tape on the body around the knob, and a little piece on the knob. Make a mark on the tape on the knob, and inch forward until the film just starts to move. Mark that point on the tape on the body, and make another mark where the film stops moving. Do it with both cameras, and you'll see that the I takes longer than the II-A to advance each frame, more of the cycle time. That's why camera designers use different shutter angles for fixed shutters on different cameras. If it had been possible to use a 180 degree shutter on the Arri I or the Eyemo, they would have done so.

 

For a more extreme example, I have an Acme kinescope movement somewhere that only pulls down on every other rotation of the vertical cam, so as to allow the use of a 288 degree shutter.

 

Bottom line, there are lots of different pulldown designs, and which one you choose determines the maximum shutter angle you can use.

 

 

 

-- J.S.

[Dan Goulder]

The simple bell crank of the model I gives you a sinusoidal vertical motion. The cardioid cam of the II-A produces the "dwell" at the top and bottom of the stroke, which adds to the amount of time that the film is stationary.

Arri initially introduced a longer dwell by putting an extra pulldown claw link onto the original "round" cam. This is most likely the point at which the 180 degree shutter was introduced. Although it's been disputed on this forum, some Arri techs refer to this variation as the 2A. Regardless of which model you want to call it, this variation on the original movement is what preceeded the cardioid cam, and also explains how Arri achieved a wider shutter opening prior to migrating to the cardioid movement.

[John Sprung]

Arri initially introduced a longer dwell by putting an extra pulldown claw link onto the original "round" cam. This is most likely the point at which the 180 degree shutter was introduced. Although it's been disputed on this forum, some Arri techs refer to this variation as the 2A. Regardless of which model you want to call it, this variation on the original movement is what preceeded the cardioid cam, and also explains how Arri achieved a wider shutter opening prior to migrating to the cardioid movement.

Very interesting -- I've never seen an Arri with this link mechanism. You certainly could get to 180 degrees that way.

 

 

-- J.S.