As I've been dabbling with handmade emulsions and alt processes, I have recently been longing for standardized exposure for my plates as I test different formulas and variables. I needed a sensitometer.
Being a die-hard DIY'er I figured this could be a project I could manage.
I know probably the most consistent and reliable light sources we have as photographers is the strobe. At basic levels, the circuit is pretty simple, reliable and very consistent, no need for additional timers or sensors. Strobe would be ideal for this project.
I found an example at https://www.jbhphoto.com/blog/2013/07/31/a-diy-sensitometer-really/ - there is a PDF of his project - TLDR; he uses a handle-mount flash, its way over-powered and too large. I don't have room for such a device. I needed smaller. I started looking at my shoe-mount strobes I might have available, but all ended up being too big for my needs - I needed smaller still.
My years of photo store work reminded me of the lowly disposable camera. Tiny flash unit. It would be perfect. I picked one up after work and and got to dis-assembly. (yes I know strobe circuits can be dangerous - don't worry, I know where not to stick my tongue).
I built the mixing chamber out of white foam-core and hot-glue and added a piece of frosted plexi to the bottom.
Then I build an enclosure out of Black foam-core and hot glue. This allowed for a second piece of plexi for extra diffusion and created a filter chamber I can add neutral density filter as needed.
To the base piece of plexi I taped a stouffer 21-step wedge, as well as B&W/color test patches from an old Kodak E-6 control strip (I knew saving those for all these years would come in useful someday!). I wrapped it all with gaffer tape for some added stability.
To make things fit a bit better, I added some external switches for power and triggering.
I'm very happy with my first tests. it works great on my slow plates, and I can easily add neutral density for faster films.
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