Question about Flickering

Hi Everyone !

I have a question, perhaps will somebody know the problem.

I got some flickering problems on my 16mm scans, you can see it on the wall between the window and the woman here:

As I’m filming myself, processing myself (Trix / reversal) and scanning myself… I don’t know where the problem is. It’s impossible for me to see if the problem is on the film itself as it’s really subtil.

Is the problem coming from my light ? but I don’t see any problem in the highlights…
Camera ? perhaps a equation between LED and exposure time ?

Or cam + process ???

So, if somebody had this problem, I would be very gratefull to have informations.

Thank you, cheers !

Gregory

In order to isolate a little bit the problem, you could re-scan the above example film with the film transport deactivated. In this way, your camera sees only a single, fixed image. If the flicker still persists, it’s not on the film (which is static now), but with your camera/light-source setup. If it’s gone, the issue is more related to the film source/film development/movie camera.

From what I see in your footage, I think it might be a sync-problem between your light source and your camera. If you are using anything similar to a dimmable LED source, you might encounter a beat between the (high) frequency of the pulsed LED source and a similar exposure time of your camera. One test to conduct here would be to change the exposure time of the camera drastically, say to at least half a second or longer, and see if the beat still persists.

By the way - I think the flicker is all over the place, it’s visible in the shadows as well as the highlights.

I had a similar problem when switching rapidly between different exposure times. The camera sensor I am using, a Raspberry Pi HQ camera, takes forever to settle to the requested exposure time. If you grab your image too early after an exposure change, you end up with noticeable flicker. This flicker is however more random (as it depends on the film’s content) than the flicker you are experiencing.

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Scan another film that is not hand processed and see if it flickers. Clear leader would work too.

Hand processing can do this sometimes depending on method used (morseg3 or lomo)

Thank you for your message…

I don’t have any film that isn’t hand processed as I process everything since my first film. I use a lomo tank… I’ll try Cpixip method to test and see if the problem is with my led/camera setup…

I second @cpixip observation that the flicker is in other parts of the film too, perhaps not as noticeable as the wall beside the window.
Is is possible you have two issues?

  1. Synchronization between the light source (at shooting) and the camera.
  2. A variation in light/exposure at scanning.

On number 2 I would also suggest to look carefully at the power supply used for the light source at the scanner. A minor voltage ripple -depending on the frequency- would be noticeable.

Thank to all of you !

So, yes, after tests, it seems that my probleme is in my RGB led… perhaps do I have voltage drop as I power my LED with my arduino…I have to find, perhaps, an external 5v power supply, I’ll let you know !!!

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Hi everybody,

after some tests, I’ve managed to have no flicker after… changing my exposure settings… when exposure it too long, I got some problems sometimes, perhaps because of the LED frequency… I don’t know for b&w yet (but no problems on the last rolls), but that s really the case in color (3 images, RGB merging).

Perhaps have I to change my RGB Led… I only got a cheap led like this: Anneau NeoPixel 7 leds RGB ADA2226 Adafruit - Leds adressables | GO TRONIC

Is there something more efficient (but still ‘low cost’ ?) ? I know nothing about led, power, frequecies etc… and I know I won’t solder different very small leds to create something.

Thank you for your help !