DIY Filmholders

[seabird]

Michael,

Congratulations. I really hope the holders work well for you.

-alas, final testing is going to have be done with film, in the field, I think. I hope to get to that next week.

I'm sure I dont need to tell you, but remember that you can perform initial tests for light-tightness using paper rather than film - should be a lot cheaper and you wont have to sacrifice any of that expensive ULF film.

Best

[David Karp]

I agree. This would be a fantastic article for the home page.

[svarzaru]

Keep us posted! It looks very interesting.

[Michael Roberts]

Thanks Sorin. I will. I'm out of town this weekend, but will finish up these first two holders and test them out next week and post results. If these work out, I'll post all the specs and then do the same for 11x14.

[Michael Roberts]

Not a lot of progress this past week, but solved a huge problem last night--the lighttrap for the dark slide. I'd been having a problem with the dark slide bowing in the middle, producing a small, but obvious light leak in the center of the opening. I considered various alternatives--

1. increasing the thickness of the felt in various ways,
2. using a more rigid covering material (e.g., some type of metal),
3. cutting away some of the felt for a narrower strip.

Option 1 did not help; same problem. Option 2 did not seem to work, either (doubling the thickness of the wood overlay). Tried option 3 and, voila, no light leak.

Turns out placing the felt right up to the edge of the groove for the darkslide was pinching the dark slide, causing upward pressure in the middle (the bowing I was getting).

I have to confess I finally brought my spare brain in to work on this--it's great having a wife with an engineering degree.

The picture is pretty ugly, as I was cutting and tearing away the felt that I had already glued in place. On the next holder, I'll cut the felt the appropriate width before gluing it down.

I also discovered I need a smaller rib lock than anticipated. Most modern holders use 3/16 inch. My vintage Kodak 7x11 holder (and, more importantly, the groove in the spring back) is 1/8. So back to the hardware store today....

[Michael Roberts]

Took a break from this project to work on the 7x11 back for my camera:

http://www.largeformatphotography.in...ad.php?t=62789

Here are a couple of updates showing the 2d try with the felt and the cover (with rib) in place.

Last step (other than putting in the double-sided tape) is to decide whether to use pull-tabs or wooden handles on the dark slides. I have been considering pull-tabs b/c it will allow me to use all of one 12x24 sheet of Garolite with no waste, but handles will help block direct light that might o/w find its way inside the holder.....

btw, the black strips under the holder in pic #1 are more felt strips I cut for additional holders.

This holder slides in/out of the spring back and the rib lock drops into place nicely; so far, so good....

[J Ney]

This is an evil post that gives hope to folks in the 4x5 / 8x10 world that larger formats can be obtained without the ridiculous cost of film holders. Assuming your 11x14 holders go well, it would nearly make it affordable.

All kidding aside, this is amazing. Great job!!!

[Michael Roberts]

Yeah, my fantasy is a 20x24 holder, using the double-sided tape, and placing six 8x10 sheets of x-ray film side by side--6 sheets total at 50 cents each--$3 for 20x24. Talk about ULF on a budget!

[Barry Young]

Okay, so ULF and odd-sized film holders are expensive--even used, vintage (very used) holders. Here is an experiment to make your (i.e., my) own. The catch is, I have zero woodworking skills and very minimal equipment (a 10-inch mitre saw, an 18-inch metal ruler, a pencil, and a bottle of contact cement).....plus access to a really well-stocked hardware store that conveniently has a good supply of craft wood....

This first attempt is for 7x11 holders:

I start with craft wood (basswood) in three sizes:
3/4 x 1/8 x 24"
1/2 x 1/16 x 24
3/4 x 1/16 x 24

(T-dimension for 7x11 holders is .25 inch.)

Here's the result of today's efforts:

Hi Michael:

Just curious how you are going to cut the grooves for the darkslides with a chop saw?

Barry Young

[Michael Roberts]

Hi Barry,
I'm not cutting grooves; instead, I am sandwiching the 1/2 inch wide wood between the two 3/4 inch wide pieces. This leaves a 1/4 inch groove all the way around the three closed sides. See the first set of pictures on page 1 of this thread.

By selecting the right dimensions of pre-cut wood pieces, there is no need to plane down the wood or rip it; just chop the lengths to the needed sizes.

BTW, I'm still working on getting the baffle/light trap right. Eric Larsen has given me a lead on finger springs that I am following up.