Using crop_rec_4k to digitize movie film - test results
My movie digitization machine came off the back burner recently and was fitted with a hall sensor for reliable half press triggering (each 1/2 press captures 1 frame into an mlv file). Here are the long overdue test results. It works great! I have been running the projector at 10 fps without any blurred frames in the 3k crop mode at 2560 x 1920 14 bits lossless continuous recording on a 5D3 1.1.3. Magic Lantern crop_rec_4k is amazing software for this purpose.
https://drive.google.com/open?id=184kg_8hzHTJwUDwKXIsQlGjavjSka6dy While the resolution may seem higher than needed for 16mm movie films, I have found that it's much easier to crop off the extra pixels in post rather than trying to make fine adjustments to the camera position during capture. Also, different movie cameras mask the image area differently with some movie cameras having image area running out to, and sometimes, beyond the film sprocket holes. I used a file on the film mask in my projector so I can record almost to the edge of the film.
a few raw frames which are h and v flipped
https://drive.google.com/open?id=1GLMwmbsmOTAPqvqUHhfwDQg2TI9QxLPz Timing between ML the projector film advance is the key to avoiding blurred frames. Running a capture and then looking through a few thousand frames to check for frames with blurs was not efficient so I set up a test to capture the projector main shaft position when ML captures the frame from the buffer.
example blurred frame
https://drive.google.com/open?id=1k-NNk0ZmYOVdCzdq45So0YJ3f1K7sMsD Here is a great video about how a projector works, it may help with understanding my test video below.
How a Film Projector Works by the engineerguy
https://youtu.be/En__V0oEJsU Running the projector at about 1/2 the Canon camera frame rate seems to be the most reliable to avoid catching the frame while the film is advancing. The film advances within about 1/8 of a turn of the main shaft. My projector shutter has been removed so I have the other 7/8 of a turn to capture the frame at a standstill. I timed the hall sensor activation so it activates just before the film advances since the half shutter activation captures a frame already in the camera buffer. Here's the video, hopefully, it makes sense!
https://vimeo.com/327622574 I find it amazing that the half-press triggering at 20fps works. I ran a previous test in 3k crop mode at 2560 x 1920 14 bits lossless for 6000 frames (the exact number expected) but there were lots of blurred frames.
On one hand, the 3x3 pixel binning at 48fps looks very workable though the lens would need a lot more extension tubes which will complicate things. The more macro magnification the harder it is to set and maintain focus due to even more shallow depth of field.
Running at 10 FPS is more than enough for my project, that said, running at full projector speed of 18 to about 24fps would benefit other projects like this since the projector drive would not need to be re-worked, which is a time-consuming task.
If there are any setting that I could change to get the 3k crop mode at 2560 x 1920 14 bits lossless to run at a higher fps please make a suggestion. I have tried FPS override, it crashes if I change to higher frame rates.
I captured a film through the projector this weekend as an example. The mlv file was converted to an image sequence then globally graded and sharpened in Davinci Resolve. This reel was shot by my Grandfather during the 1969 United States Grand Prix at Watkins Glen.
https://vimeo.com/327447552
Show Posts
