Thoughts about 3D printed film holders for scanning

[Corran]

I've been thinking lately about 3D printing some film holders as my scanner doesn't use holders really, but has ANR plexi "hold-down" plates. However, I assume others could benefit as well if they needed replacement holders or even custom holders for odd film sizes.

I wanted to brainstorm some ideas for this and get some suggestions.

My initial thought is to make a simple two-part holder that snaps together and has a slot for the film to slide in. The opening would be just the right size for whatever film of course, with about an inch of material on each side extra. One side would have holes in the side material, with the other having pegs that are slightly larger so it'll press/snap in and a channel for the film to slide down. At this point I am hoping it would just stay put and you wouldn't need to take it back apart - just slide the film into the holder - but most holders use some sort of hinge. I wonder why, and do I really need a hinged holder?

Any other ideas?

I can 3D model these as I've been learning how to use SketchUp. I can make the 3D models available here once I'm done. I'm thinking of making of course 4x5, but also smaller formats. 8x10 is too big to fit inside the printer I have access to.

[Oren Grad]

I'd worry about film flatness with a slide-in design - not that most hinged designs don't have their own issues in this respect. For me, something that holds the film under a bit of tension would be of greatest interest. How to do that in a simple plastic device and without damaging the film is an interesting design challenge, I think.

[Corran]

Some tension would certainly be nice. I'd welcome thoughts on that design implementation.

[Tin Can]

Look here for an idea. http://www.largeformatphotography.in...l=1#post900372

I use 2 of them. Hard for me to load and if you set it down on a table, the updraft will shift and bend the neg.

Very touchy, I like them.

But many will complain they lose the rebate...

[Corran]

Thanks Randy. I actually have and use a Negaflat...will have to consider ideas about how to implement that with a home-made item. I am not sure I could do it.

[Tin Can]

Thanks Randy. I actually have and use a Negaflat...will have to consider ideas about how to implement that with a home-made item. I am not sure I could do it.

It won't be easy. I use my 4x5 NegaFlat all the time, the 8x10 is not as easy, but my 8x10 enlarging is not prolific.

You may want to look at Glennview's solution. A different sort of stretcher.

I also have 5x7 Saltzman stretcher than can stretch 5x7 and smaller. NegaFlat-like.

The trick, as you, know is to make one than can work from 1-3mm in height.

[Ben Syverson]

I like the initial idea of a two part holder. Rather than sliding the film in, perhaps the holder could snap together to hold the sheet in tension? Something like the attached…

One side could provide 1mm rise above the platen, while the reverse is 2mm or 3mm.

[Corran]

Thanks for the input Ben!!

I thought about the that, an interlocking channel, but I wonder if the sheet will just bow in the center when it's snapped together? See the attached crude addition to your diagram.

The Negaflat mentioned above works by pulling the film outwards, so the tension is achieved w/o bowing the film.

Of course 3D printing is cheap, so perhaps just trying it would be the quickest way to figure out!

[Ben Syverson]

It's worth a shot! A lot depends on how much DOF you're working with on the scanner. For example, on my Epson 4990, there's a difference in sharpness between 1mm and 3mm, but it's subtle even at 2400 PPI. So even if the center of the film sagged by 0.5mm, it wouldn't be detectable. But other scanners may have less margin for error…

[Corran]

Definitely true for many scanners. I've got a Screen Cezanne, which can really deliver some stunning resolution, so I think even that much sag would be detrimental for me.

However, you've got me thinking, and specifically about the P99 ANR plexi that I've been told is a replacement for the plates that hold down film on this scanner. I wonder if I could simply make the film channels thicker and buy some plexi for each side of the holder.

Lots to think about. I'll start working on some 3D models in SketchUp next week.