Building 11x14 Film Holders - Feedback on an idea

[MAubrey]

I'm building a set of film holders for my nearly complete homemade 11x14 camera (I can't build the back until I have a holder). Originally I was going to build based on the ANSI standard and maybe I'll still try to stay close to that, but lately I've been thinking about film flatness. Grooves in the holder aren't going to do it the same way they do with smaller formats.

But I had the thought: what about magnets?

I'm looking at getting a sheet of .001" (~.0254mm) low carbon steel from to line the inside of the holder and then use magnets to hold the film flat. It'd be more work leading film in the darkroom, but it seems like it would solve the flatness problem fairly well.

Any opinions or thoughts?

Has anyone ever tried anything similar?

[barnacle]

Er, where are you planning on putting the magnets? Doesn't the film need to be between the magnet and the plate, where they're going to get in the way of the image? Or are you thinking just around the edge?

Neil

[MAubrey]

Yeah, just around the edge. I've sketched something out on paper. I'm thinking that the magnets would basically cover the film as much as the grooves do on a normal film holder. McMaster-Carr has "Increased-Pull" magnet strips as thin as 1/32", which would do the trick.

Figuring out how to still have a darkslide is the larger issue for making this work. It'd have to be less than traditional...

[MartinP]

You could make it work for your 'own' standard and also the ISO/ANSI standard (assuming there is one for 11x14) by increasing the film-holder depth to allow room for the magnets, then using a carefully selected spacer-shim between camera and film-holder to increase the distance when using ISO/ANSI standard film-holders (which of course don't have your magnetic system). That would give you one position for the focussing screen and the possibility to use any future holder you came across, if it was made to standard measurements.

Most likely the spacer-shim would be simplest if made from a standard thickness material, to allow easy replacement, then your personal standard film-holders could be designed to suit both the shim and the extra depth to accommodate the magnets?

[plaubel]

Since my 12x16" double-filmholders take plates, I use two aluminium plates and some tape to fix my sheets.
I gave up my own magnetic idea.

I believe in my tape, but if you like my idea, you alternatively could try to glue some neodyms into such an aluminium plate and then covering the film with this thin carbon steel.

For me, fixing the film onto a separated plate instead directly into the holder, it gives big advantages concerning fiddling with the stuff, and flatness.
My first step is taping the plate edges in light, with one stripe, but both sides.
Then I loosen one side, so it can take the film, and I dim the light to red (Xray film..)..

Next I fix one edge ( the smaller side) of the film, and then I can pull the film a bit in the other direction, meanwhile pressing and giving the plate a slightly concave form with my other hand - luckily no filmholder disturbs this process.
After fixing and "deconcaving" the plate, , I load a flattened film, fixed onto a sturdy plate.
The tape steals me 3 to 5 mm at each side of the film.

Sounds ugly, maybe, but the whole process needs less time then writing ( and translating a bit) this text.
And: once taped the aluminium, I can use the tape for 4 or 5 other sheets.

Ritchie

[MAubrey]

You could make it work for your 'own' standard and also the ISO/ANSI standard (assuming there is one for 11x14) by increasing the film-holder depth to allow room for the magnets, then using a carefully selected spacer-shim between camera and film-holder to increase the distance when using ISO/ANSI standard film-holders (which of course don't have your magnetic system). That would give you one position for the focussing screen and the possibility to use any future holder you came across, if it was made to standard measurements.

Most likely the spacer-shim would be simplest if made from a standard thickness material, to allow easy replacement, then your personal standard film-holders could be designed to suit both the shim and the extra depth to accommodate the magnets?

That's a good idea.

[MAubrey]

Since my 12x16" double-filmholders take plates, I use two aluminium plates and some tape to fix my sheets.
I gave up my own magnetic idea.

I believe in my tape, but if you like my idea, you alternatively could try to glue some neodyms into such an aluminium plate and then covering the film with this thin carbon steel.

For me, fixing the film onto a separated plate instead directly into the holder, it gives big advantages concerning fiddling with the stuff, and flatness.
My first step is taping the plate edges in light, with one stripe, but both sides.
Then I loosen one side, so it can take the film, and I dim the light to red (Xray film..)..

Next I fix one edge ( the smaller side) of the film, and then I can pull the film a bit in the other direction, meanwhile pressing and giving the plate a slightly concave form with my other hand - luckily no filmholder disturbs this process.
After fixing and "deconcaving" the plate, , I load a flattened film, fixed onto a sturdy plate.
The tape steals me 3 to 5 mm at each side of the film.

Sounds ugly, maybe, but the whole process needs less time then writing ( and translating a bit) this text.

Ritchie
That's clever. I'll take a look at some plate holders and try to get a visual of what you're saying. I like the sound of it though.

[plaubel]

Yes, for me it works best, and with flat film.
The plate holder don't care about glass or aluminium :-)

Ritchie