AATON 35III Single Frame / Stop Motion issue with split frames

[Robino Jones]

Shot a stop motion test using the AATON 35III handgrip which serves as a simple intervalometer with 1/4th exposures and the frames are split in half horizontally. The top part of the frame has a different exposure than the bottom half.

See a video of the issue here:

 

After some research I came across an old CML post about film  “time-lapse issue”  where someone is describing something somewhat similar to me. https://www.cinematography.net/edited-pages/timelapse_problems.htm  The issue in this thread is caused by light leaking.

My camera works great at all frame rates, I only see those split frames when I take single frames with the handgrip or when I flip the switch to test mode to move the mirror out of the way.

To verify that the single frame was exposing / working correctly, I sharpie’d some negative and looked in side the mount to see if everything was ok and it seems fine. 

See video of this test here: 

As you can see the film is not moving during exposure.

If anyone has any insights on this, if my camera is defective or if I need to figure out light leaks please let me know!

[Tyler Purcell]

Was the viewfinder closed? 

[Robino Jones]

44 minutes ago, Tyler Purcell said:

Was the viewfinder closed? 

I don’t recall - this was done a while back. But it was shot in a very dark room. Only light was a light panel in front of camera that I was drawing on.. I typically close the viewfinder from the toggle on the camera body under the handle. My bet is that it was closed and for sure there was no light hitting the back of camera / viewfinder because the room was in the dark

[Dom Jaeger]

Cameras without a focal plane shutter like Aatons and Arris usually need a capping shutter to do stop motion, because the angled mirror shutter can allow light to leak past over time. I don't know of one for an Aaton 35III, but here's the manual for the one for a 435:

http://www.aoassocies.com/wp-content/uploads/2016/12/arri_ICS1_SFHC1_usermanual_en.pdf

Alternatively, putting the lens cap on between each single frame exposure will help.

[Robino Jones]

34 minutes ago, Dom Jaeger said:

Cameras without a focal plane shutter like Aatons and Arris usually need a capping shutter to do stop motion, because the angled mirror shutter can allow light to leak past over time. I don't know of one for an Aaton 35III, but here's the manual for the one for a 435:

http://www.aoassocies.com/wp-content/uploads/2016/12/arri_ICS1_SFHC1_usermanual_en.pdf

Alternatively, putting the lens cap on between each single frame exposure will help.

Ok yes that makes sense.

So my camera is fine, I'll shoot another test with cap on between frames and see what happens. to be continued.

[Webster Colcord]

This was the case with an Arri 2B that I purchased decades ago; it had been used for stop-motion when I got it and came with a sophisticated Norris capping shutter. But I'm told you can make a poor man's version by using just a little flap of cardboard -  lift it up when you're taking the frame, put it down between frames.

[Tyler Purcell]

22 hours ago, Dom Jaeger said:

Cameras without a focal plane shutter like Aatons and Arris usually need a capping shutter to do stop motion, because the angled mirror shutter can allow light to leak past over time. I don't know of one for an Aaton 35III, but here's the manual for the one for a 435:

http://www.aoassocies.com/wp-content/uploads/2016/12/arri_ICS1_SFHC1_usermanual_en.pdf

Alternatively, putting the lens cap on between each single frame exposure will help.

Ah interesting, so there is just enough light leaking around the mirror between frames. 

What about the use of mirrored reflex cameras in special effects? Maybe the 1fps doesn't allow enough light to get in and maybe that's why Aaton limits the camera's minimal speed to 3fps.

More testing needs to happen! 

[Robino Jones]

1 minute ago, Tyler Purcell said:

Ah interesting, so there is just enough light leaking around the mirror between frames. 

What about the use of mirrored reflex cameras in special effects? Maybe the 1fps doesn't allow enough light to get in and maybe that's why Aaton limits the camera's minimal speed to 3fps.

More testing needs to happen! 

Yes It makes sense that this happened in my test since the light panel I was drawing on was very bright and shining directly through the lens. Must have been waiting at least 10 seconds min between frames..

I might design an automatic capping shutter for my lenses if my next test works (by putting lens cap on between frames)

[Robino Jones]

Here's an update - I did 2 tests this morning.

First is outside and had to put on the mattebox because I needed a lot of NDs for the 1/4th exposure.To block the light between frames I taped a flap of duvetyne and was moving it out of the way when taking frames. This was a fail and I still saw the split screen. (i was expecting it..kind of ?

For the second test I did it inside and used the lens cap on the lens to block the light between frames - and it worked! The table was lit by the window light behind me and that's why you see a bunch of shadows moving but there's no split screen.

Shot the tests on leftover 200T (5213) and hand processed it in Ilfosol 3. I looped each sequence twice since it's very short, I can only load around 3.5feet on each "still film" stainless steel reels.

So I'm happy - my camera is fine and as Dom and Webster said, it's because of the mirror shutter. If I need to shot some stop motion i'll just make sure to do it in controlled lighting and use the lens cap. Thanks for the help guys, scan is below:

 

 

[Dom Jaeger]

No worries Robino, thanks for the update!