strange light flicker cause?

lars preisser · March 10, 2022

Hello, I am an amateur when it comes to cinematography and I encountered a strange light flicker on some of my recent footage. The flicker seems to resemble the old 4:3 aspect ratio of the camera but I got the acl eclair II converted to S16 not too long ago and I wonder if something has been done wrong or if its just some other issue that happened during filming or scanning? I also have scenes where the issue is absent. I noticed the motor knob on the left side of the camera became loose after the camera was in Ireland for conversion. I would be very thankful for any hints.

vimeo link: https://vimeo.com/686817666/e80c7c5d47

Heikki Repo · March 10, 2022

Hi Lars,

Resembles the flicker I got back when I had mine converted.

Look around the TS-mount and check if there is a hole in there -- mine had one there. You can use a flashlight to see if you get light inside some other way than through the lens...

Heikki Repo · March 10, 2022

For comparison:

lars preisser · March 10, 2022

12 minutes ago, Heikki Repo said:

For comparison:

Hi Heikki, that looks indeed very similar. Thank you very much for your help I will check it out tomorrow. I guess the solution will be to put some tape over it?

Perry Paolantonio · March 10, 2022

Something else to look at: we've had two customers with ACL S16 conversions that had a similar issue. In both cases the problem wasn't a light leak per se, but some of the black paint inside the camera body had been scraped off during the machining. Light was bouncing around inside the camera body, causing reflections that lead to a similar flicker. It's worth taking a look to see if you need to touch up any painted areas.

Heikki Repo · March 10, 2022

1 hour ago, lars preisser said:

I guess the solution will be to put some tape over it?

Yes, that works perfectly. Also, if there is a hole where I had it, using a lens adapter that uses the TS-mount works as well. My issue wouldn't have come up if I hadn't used the c-mount, leaving the TS-mount edges bare (and the hole in it!)

Heikki Repo · March 10, 2022

26 minutes ago, Perry Paolantonio said:

Something else to look at: we've had two customers with ACL S16 conversions that had a similar issue. In both cases the problem wasn't a light leak per se, but some of the black paint inside the camera body had been scraped off during the machining. Light was bouncing around inside the camera body, causing reflections that lead to a similar flicker. It's worth taking a look to see if you need to touch up any painted areas.

Now that sounds wild, but I guess that could happen too. The thing is, even though there was that hole in my camera, I didn't get so bad flicker unless direct light was hitting it. In shade, or not facing direct light the flicker could pretty much disappear, as you can see in my video.

Must have been quite shiny innards in your clients' cameras! ?

Perry Paolantonio · March 10, 2022

12 minutes ago, Heikki Repo said:

Must have been quite shiny innards in your clients' cameras! ?

haha. it's subtle, but the flicker was definitely there before it was repainted, and gone afterwards! I bet with something like Black 3.0 paint, it would be totally eliminated. Though I'm not sure how well that stuff will stand up over time, since it's more of an artists paint than an industrial paint.

Heikki Repo · March 11, 2022

9 hours ago, Perry Paolantonio said:

haha. it's subtle, but the flicker was definitely there before it was repainted, and gone afterwards! I bet with something like Black 3.0 paint, it would be totally eliminated. Though I'm not sure how well that stuff will stand up over time, since it's more of an artists paint than an industrial paint.

Very good to know!