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Patrick Barry

Eclair flickers... help!

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I'm happy to tell you I have found the cause. The problem was caused by a light leak, however not from the viewfinder. Many thanks to all of you contributing to this discussion. :)

 

Well don't leave us hanging... where was it?

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Heikki,

Can you tell us what it was? Don't be embarassed if you missed something obvious (maybe we all did). The feeling of relief should fix that. Was it a reflection from a filter or something like that?

 

Cheers,

Gregg

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Over the years I have gained quite a bit of experience with crystal camera motors and Hall effect motors. I believe the result of the flicker is because of the early hall effect drive motor. These motors generally do not have overlapping pole pieces and they tend to hunt between the poles, this "hunting" area is essentially a dead point in the rotation of the motor itself. If you notice in some of the transfers posted the flicker oscillates at a slow rate... comes and goes. I believe that this is caused by a slight back oscillation into the mechanism itself from the motor hunting. Cinema Products cured this issue. Aside from adding variable speed as part of the conversion on the MIALA they also added a small high mass flywheel to the motor shaft between the motor and the inching knob. This was enough to give some kinetic energy to the motor itself and smooth out it's rotation. You'll notice that area of their converted motors is also wider and has a different cover to accommodate that flywheel. There is little kinetic energy stored in the ACL itself to help filter out this hunting between poles that the motor does. Later ACL motors do not have this flickering problem. I just bought another ACL(French) with MIALA motor and I'm anxious to see if it flickers or not. If it does I'll machine and add a small high mass flywheel myself in place of the inching knob and then shoot another test.

 

What made me think of this? Years ago I built a VistaVision projector because I used to do a lot of location dailies. I used a Bodine Hall effect drive motor on this projector because it was 1/4 hp and would fit in the palm of your hand. It's a very light efficient little motor that Bodine sells to this day but it caused a slight back oscillation into the projector mechanism which could be heard and which was viewable with a variable speed strobe. Adding a small flywheel to the motor shaft added enough kinetic energy to overcome the hunting the motor was doing and it fixed the problem. The projector was subsequently used on a lot of films and I had zero problems with it. Anyway, this projector oscillation is no doubt similar to whats happening in the earlier ACL's. I never heard of someone with a CP motor having any flicker issues nor with the later ACL 2.

 

Hekki's flicker problem may also have been light leaking in through the filter holder.... Always cover that thing with gaffers tape!

 

 

Just my thoughts....

 

Mark Gulbrandsen

SLC, UT

Edited by Mark Gulbrandsen

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A few weeks ago I wrapped the super16 shoots on my short film. Today I got to see the scanned material. I'm happy to tell you there were no problems whatsoever with my camera. A few layers of black tape over the leaky spot took care of the flicker problem. I'm beginning to suspect some of the flare issues were also related.

 

So, if you have an Eclair ACL and have problems like mine, you might want to check your camera with a bright led light, especially the front of the camera.

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First half of the material was shot with those Contax Zeiss lenses with long lens hoods. Despite that there is still that odd light...

Hekki, do you have a Contax mount for your ACL? Or have you remounted some Contax Zeiss lenses?

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Hekki, do you have a Contax mount for your ACL? Or have you remounted some Contax Zeiss lenses?

 

I have a Contax Yashica to C-mount adapter. The one I used was lower quality with shiny insides so I had to put some black tape there as well to remove any chance of light bouncing from it. I have since then bought an old Beaulieu adapter which doesn't seem to have this problem but I have to test it first.

 

Contax Yashica lenses are cheap and produce quite good looking images, however there are few wide angle lenses available and those are rather slow. It would be great if everything could be done with just one adapter. At the moment I'm using 10mm and 16mm Switars for wider than 28mm.

 

I have to admit, I have been wondering if I could find some good Nikon (G) to C-mount adapter. Would be interesting to see how Tokina 11-16mm would work with Super16... ;) This might do the trick: https://www.lensadaptor.com/nikon-g-c-mount-adaptor

Edited by Heikki Repo

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Are some of the still lens camera mounts (such as exist on the front of adapters) simple enough that one could just machine a cylinder to fit between the mount and the TS fitting that joins to the ACL?

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There are lots of quite cheap Contax & other still lens adapters to C-mount available on Ebay. It might be possible to either add the cylinder over those adapters or to remove the mount from the adapter and fit it on that kind of cylinder. However, keeping the flange focal distance precise enough might be a problem.

 

Les Bosher could make me a Contax to TS adapter, but £220 is a bit too much as the wide angle is so lacking on the Contax side.

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