Need help with LED power for my custom scanner.

[Robino Jones]

I built myself a 35mm scanner using an optical printer head with pin registered movement. It's working and I'm really happy with the results I'm getting.

I capture using a RED EPIC Dragon.

For the illumination I use a 50W Yuji Led chip (5600K version) https://store.yujiintl.com/collections/frontpage/products/bc-series-cob-400l and it is powered using this PSU https://www.amazon.com/gp/product/B01N374QPE/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=13

The issue is that there are scan bars slowly moving down in my scans when shooting at shutter speeds other than 1/60th. It's like a darker horizontal band taking about 1/4th of the screen and you can see it moving when playing back a scanned clips.

It sucks because I could REALLY use HDR in this application but with the EPIC HDRX feature set to 1/60th for A Frame, then the X frame track (is using a higher shutter speed that I cannot manually set, you can only select how many stops you want) has flicker issue.

Any suggestions on how to improve my LED power or other power supply recommendations, so I could use more shutter speeds and not have to worry about scan bars / flicker ?

Someone suggested I install a High Speed Dimmer between the power supply and the LED Chip similar to this and said it would improve flickering. What do you guys think?

https://www.amazon.com/dp/B06W9MH8QQ/ref=asc_df_B06W9MH8QQ5044497?smid=A2VAJ7VEVYWQKW&tag=shopz0d-20&ascsubtag=shopzilla_mp_1191-20;15027333268181517694510070302008005&linkCode=df0&creative=395105&creativeASIN=B06W9MH8QQ

[Perry Paolantonio]

It's been a while and I've actually forgotten most of the details, but I built a custom lamphouse for a 35mm scanner rebuild project a few years ago. RGB LEDs, for doing three-flash scanning, as well as an IR array for making dustmaps for restoration software. Never had any problems with flicker or scan lines, but I was also using a machine vision CMOS camera and not a digital cinema camera. There may be inherent differences there, since I don't really know what the Red camera you're using is doing when it snaps a frame.

 

Here's a look at mine - never quite finished it, but I did get it working for all three colors plus IR (and you can do white by mixing RGB). I 3D printed a simple lamphouse lined with mylar, and had some diffusion material on the opening to soften the light a bit. Seemed to work quite well.

 

https://www.flickr.com/photos/friolator/17037539117/in/album-72157644369553789/

 

You can click forward on that, there are several shots and a short video of it in action. The earlier photos in the album are the disassembly and rebuild of the scanner transport. Everything is controlled with an arduino.