I had a problem. I have an older flatbed scanner that is designed to scan 120 film. This is all nice and well, but there is an obvious problem when I want to scan 4x5 inch large format film. Thing is, the scanner wasn't designed for it. So I resort to scanning in multiple parts and re-assemble everything in Photoshop. But this brings another problem: I can't rely on the scanner's edges to align the film because the scanner needs a calibration area before the negative. Annoying...
So I designed this thing a few weeks back and it had been sitting on my computer ever since. But after reading this thread about people who were also swearing every time they had to scan 4x5 film, I decided to make mine. I did change a few things to make assembly easier. Originally I was planning on having the device laser cut. But since it costs way more than the device is worth to have this done, I decided to simplify the whole thing by removing the top layer and replacing it with glued-on Popsicle sticks. As easy as pie.
To build it, you will need this template
https://drive.google.com/file/d/0B1dmZoIlURfDZklPTzdWWW9kU1k/view?usp=sharing4 popsicle sticks, some glue, an X-acto knife and a good non-slip steel ruler.
Just print the first page, lay the template on the cardboard and cut out the parts like on my picture.
Then use a piece of 4x5 film (or print the top layer on page 2) to mark the edges with a pencil. Cut the sticks to size and glue them in position.
That's really all there is to it.
To use it, you put the negative on it, align it with the left corner of the scanner and scan. Once this scan is over, keeping the same exposure settings you simply slide the card to the right corner and scan part 2.
Once the files are on your drive, you open Photoshop and select File/Automate/Photomerge...
Select Intactive layout and get the files. Photoshop will attempt to auto align the files (which works 99% of the time) and if you like what you see, just give it the OK and wait. That simple.
I hope you will find this contraption useful.
Here are some of the pictures of the project. As you can see, it's pretty simple.