8mm Film Scanner ... my build

[jankaiser]

@dgalland, thank you! These are some very interesting points for discussion.

@dgalland

My project classically uses a jpeg capture with multiple exposure fusion and I read with great interest the discussion on RAW capture.This is really interesting to consider, as multiple capture slows down the process considerably, especially when you take into account the time required for a change of exposure.
But I’m not at all sure that you’ll get such a good result ?

Personally, I think the results are very nice. This is of course from a perspective of someone looking for a result that looks good, not necessarily with a 100% eye for what one might call “archival” quality. @cpixip is doing some fascinating experiments at the moment on this topic, which I think we can all learn a lot from. I think the results so far can be summarised as “Exposure fusion is still better in terms of actual quality, but RAW capture is a very capable compromise.” That might of course change once we consider more capable cameras than the Pi HQ camera for their RAW captures.

@dgalland

On the projector:
The EUMIG (I have one) is a little marvel of extremely compact mechanics that allows you to make very clean mounting like yours. However, access to the drive mechanism and projection window is rather difficult. With the ELMO, I was able to remove the three-blade quite easily, mount a toothed pulley on the main axis and enlarge the projection window as much as possible.

Yeah, so I’m quite happy with my little Bolex projector especially because, as you mention, the mechanics and available mounting options make it very easy to mount your own hardware in there once you’ve gotten the original motor out (which I have to admit was a bit of a pain to do). However, I do also have one gripe with my choice of projector, pertaining to, as you mention, linking the drive mechanism. One annoying problem I have here is that with the toothless belt and pulley that’s already on the projector’s drive shaft, the belt occasionally slips. This would be nearly impossible if I could mount a toothed pulley and belt, or maybe even a proper gear like @Manuel_Angel has done. While something toothed would be my favourite fix, for the time being I am seeing two issues with the toothless system that might be causing the slipping:

• Improper belt tension: I’m no mechanical engineer, so I just winged the position of the stepper’s pulley and as a result the belt tension. It might be worth doing properly, which includes using a V-belt pulley on the stepper side and a V-belt, which would be what was originally used on the projector’s motor. Interestingly, the round belt I am using now was sold as a spare specifically for this model projector.
• Regreasing the mechanism: Another reason for the belt slipping could be that the mechanism has too much resistance. The projector was very beat up and dirty when I got it (which is why I didn’t mind converting it), so the lubrication is probably far from perfect after 50 or so years. Unfortunately, I don’t know what the proper kind of grease for these is and have no experience doing something like this on a film projector. In addition, there are parts of the mechanism, specifically the speed selector “gear box” that I still don’t quite understand and don’t really dare to mess with.

In the end, it’s probably a mix of both, but I welcome and value any more ideas and input on this.

@dgalland

On the lighting and the diffuser:
There are discussions in this forum about the best position for the diffuser, close to the lamp or close to the film?In my experiments, it seemed to me that a diffuser close to the film reduced the effect of scratches (to be confirmed ?)

This theory sounds about right. I can confirm that changing the diffusor significantly reduced the effect of scratches. I’ve written about this on another thread where I also shared the distances on my scanner. I believe the question of how far away to place the diffusion was also discussed extensively in relation to the Essential Film Holder where the distances are adjustable. Note that on my build the distances are simply where things were easiest to mount and I made no effort to “tune” this aspect. Nevertheless, the results look good to me.

@dgalland

On focus
A good focus is fundamental. Are you really sure that the focus is optimal in your video examples?
Your MENGS W-160 slider is interesting, but I’m not sure how precise it is, and it has only one axis.
Even if it’s a bit expensive, I’ve never regretted my purchase of an XYZ axis sliding table.
Yart’s code includes a numerical calculation of a focus indicator, which shows that a micrometric displacement is useful.

The MENGS W-160 slider is certainly not perfect, but it’s good enough and actually amazing for the money. It’s definitely possible to focus well enough to get an image where the grain, the dust and the scratches are sharp to the pixel, which is the case in my examples. It’s just a little annoying at times, because, while the slider is much better built than others I have had the displeasure of using at this price point, there is definitely still a touch of play when adjusting it back and forth that can certainly been “felt” when focusing on Super 8 film. My vertical and orthogonal axis are very coarse hacky adjustments, but luckily I’ve only adjusted them once and never again. I would also like to point out that the height on whatever the camera is mounted on was a point of consideration for me. An initial assembly I had was too high and would have required lifting the projector as well. All in all, I think the XYZ axis sliding table is definitely the more ideal and pleasant-to-use solution, but the macro slider and wooden plate can absolutely achieve the same results if you have a little patience to focus them right. I might upgrade at some point, but for now there are more pressing improvements to make.

@dgalland

On sofware, everyone can have their own ideas !
My images are transmitted to the PC for Mertens merging, but storage on an SSD is also a good solution.
I’ve done a lot of web development in my work, but in this case I’m not sure that control via a WEB interface is the best solution. It introduces additional complexity as soon as the interface is enriched, as in my project or Manuel’s ? I prefer to stay 100% Python

I don’t actually think that the web interface introduces any more complexity than a Python client, for example based around PyQT, does. The latter is actually what I started with. I don’t regret moving to the web interface and actually found it easier to develop for than I did with the Python client, both in terms of network communication and building the UI, especially because there are so many resources online. Another advantage for a film scanner here is that it requires no installation at all on the client device. I have to say, though, that all of this was made much easier by frameworks like React and TailwindCSS which had some initial learning curve to them. In my case learning them was part of the fun because in my work I rarely get out of the Python world.

@dgalland

For post-processing:
You use applications like Lightroom, FinalCut, DaVinci, Neatvideo, … for a good result !
I personally use Avisynth for corrections and ffpmeg for encoding (X265, AV1, …), the possibilities are endless but the initial investment is difficult ! Another advantage, when you have a large number of films, is the possibility of automation.

Actually, Avisynth is something I am very interested in! I know there are some pretty cool scripts out there that people have tuned extensively for Super 8 film scan post-processing. However, I am on a Mac, so unfortunately I was never able to try them. Being able to run and try them on Mac would actually be amazing!