I build my own 30x40cm ULF camera (unique design)

So it all started about half a year ago, I got my hands on a 30x40cm film holder (that is roughly 12x16 inches). Obviously it is impossible to find a fitting camera so I decided to build one myself. I also decided that I'm not a good enough builder to hassle with bellows, front and back standards etc, so I settled with a box design. It is big and heavy, but honestly any ULF camera is big and heavy... I don't plan to backpack it anyway.

I made a YouTube playlist of the build process so far...

Your comments are welcome. Also if you have modification ideas I can still do whatever I (you) want.

Thanks for showing the process. With a camera like this, you don't put it in your suitcase - the camera is the suitcase!

The diagonal of a 30 cm x 40 cm rectangle is 500 mm.

In the video, the lens shown is a 360 mm f/9 APO Nikkor. This lens has actual focal length f = 356 mm and the coverage angle is 46º per the Nikon data. The coverage at infinity is 302 mm. This camera needs a lens with greater coverage.

The shortest APO Nikkor with at least 500 mm infinity-focus coverage is the 610 mm f/9. Its infinity coverage is 517 mm.

https://www.savazzi.net/download/manuals/Apo-Nikkor.pdf

Another thing to consider is that the lens should be parallel to the film plane - if you look at the camera from the side. If the lens is not, the left side of your negative may be unsharp, or the upper part may be unsharp - or the right side and the lower part may be unsharp at the same time.
The lens should be parallel to the film plane - this goes for any film format - but especially at such a big format it is even more important. Because of the big image circle needed you have to use much longer focal lengths than with smaller formats - and longer focal lengths have fewer depth of field. DOF can compensate a bit for lenses not being parallel to the film plane, but only if DOF is sufficiently big.
On such a big format room for error is small.

Depending on how these two wooden boxes are joined and on how you can adjust sharpness, you should check for parallelism of lens and film plane - and undertake measure to improve it if insufficient.

Thanks for all the useful comments! I see image in all corners on the ground glass. The quality surely degrades but it can be improved by the aperture and focusing distance... yet I still have to finish the build and make test shots. I also have a Carl Zeiss APO 45cm f9 lens to test...
I'm not that worried about the parallel planes: the two boxes are attached to a common rail, so they cannot really move independently other than sliding back and forth. But you are right: the margin for error is very small and this is not a precision build at all, so anything can happen. That is part of the charm of such project, isn't it?

You`re welcome! My comment was meant to save you from frustration, but i see where you`re heading to. Interested in the results.

There is a new episode (#11) in the playlist, showing all the boxes coming together and the "focusing mechanism" is working as well...

I did the first "field test" with my 30x40 ULF box camera. It went relatively well. I found some light leaks and I scratched my Xray film (nothing to do with the camera) so I have not much to show for in the end, but it was plenty fun.
I also made a video showing what is going on. It's in Hungarian, but there isn't much yapping anyway... I developed the Xray in D23 1+2 8 min, the Foma retro special 320 neg in its special Retro developer (that looked weird), and the paper negatives in Adox Neutol. I used matte / pearl paper, but maybe for negatives glossy would be the best?! Anyone has experience comparing those?

Congrats, those negatives look really nice!

milane said:

I scratched my Xray film

Click to expand...

That stuff scratches if you so much as breathe on it. It takes a very delicate touch indeed. I never really got along with the double-sided stuff also for this reason.

If you jump to 27:10 in the video I found out why are there so many scratches. The developing tray actually has a small bump in the middle... but there are so many ways to go wrong.
But also there are so many details, it's actually almost 3 rolls of 35mm film surface. I can't wait for the Ilford ULF program this year...
Here is an example zooming in (as I said I found some light leaks in the design, and already solved them, you can see here mostly on the left):

milane said:

The developing tray actually has a small bump in the middle

Click to expand...

Yup, I've had that exact cause ruin some x-ray sheets as well.

More concerning is the fog you got in that riverside shot. Have you determined the cause of that yet? Sorry if it's in the video and I missed it!

The nice thing about these big negatives is what you can do in terms of alt. process contact prints. Is that what you're planning on doing with them?

The fog was because of the light leak, I already fixed that, but there are more tests to come...
And yes, my plan and main interest is to do alt. processes, where 8x10" is not big enough, that's why I had to start this whole project.