My 3D printed test strip maker: Test Strip Omega

[BHuij]

I just finalized all the prototyping and testing and video making and product photos for this design. I think I've shared earlier versions of it here before, but I figured I'd post again. I've been using this test strip making tool for a few years in my own darkroom, and personally find it indispensable.

LINK

Copy from the Printables description:

You thought the Ultimate Darkroom Test Strip Maker was… well, ultimate. But you were wrong. Because I famously don't know when to stop innovating.

Presenting the newer, bigger, better, more polished, Test Strip Omega (and fun-sized sidekick, Test Strip Omega Zero Calorie).

Inspired by procedures outlined in Way Beyond Monochrome, Test Strip Omega allows for extremely simple creation of localized test strips when making enlargements in the darkroom. Print the same area of projected negative at different exposures onto 3 evenly-spaced strips on a single 4x5" sheet of paper (1/4 of a standard 8x10), and revel in how easy it is to directly compare the results.

Budgetary metabolism not what it used to be? Test Strip Omega Zero Calorie is even more economical in its use of expensive silver gelatin paper, using a 2.25x4" sheet (1/8 of a standard 8x10), and allowing for 4 different exposures.

You're only a day of 3D printing and a laundry list of odd hardware purchases away from producing test strips that would make Chris Woodhouse and Ralph Lambrecht ask for your autograph. Particularly if you use the included stop-based timing PDF attached to this Printable for locating your perfect base exposure.

Fusion360 files have also been provided under a Creative Commons license so you can remix and create a Test Strip Omega for any of the odd sizes you want to use. I know you make triangular test strips, Todd. You weirdo.

Share it far and wide, just don't try to profit from my design. The last thing we need is more barriers to entry for new darkroom printers.

 

[koraks]

That's nifty!

 

[Luckless]

Far fancier than mine, which is just a mask of heavy black card stock, and a 'sled' with stepped notches cut in so I can feel the alignment. However it has the issues of not having the greatest hold and stability of position since I just hold it down with some magnets. Might have to make some adjustments to your model now that I have my 3d printer running smoothly again.

I settled on 5 test patches on a 4x5 sheet as a compromise on details. Might re-cut the rig to do a full 1x4 inch patch as my original was intended to be used with a second mask to let me burn one edge to full black while leaving the other at full white, and a space for a front facing label... But I misplaced the second mask and find I don't actually label them, so kind of wasting paper area.

Also combining it with a timer that lets me set a series and automatically advance the time for the next test exposure, which makes it a breeze and very hard to mess up.

The 5 test patches gives me my estimated target with two additional tests either side, and I find that to be a very handy space to work in. And I seem to be able to find a patch with shadows and highlights I care about with around a 1x4 patch while giving enough visual detail to make useful judgements. But going much smaller than that feels harder to work with.

 

[BHuij]

Awesome! You and I darkroom print much the same way, I suspect haha. My first iteration of this design looked almost identical to yours, but I quickly got fed up with how fiddly it was to use.

You could easily remix my design to do 4 or 5 strips on a 4x5 sheet. The full-size version of this absolutely maxed out my 230mm square print bed on my Ender 3 though, so if you wanted to go any longer, you'd be looking down the barrel of splitting the print up into separate chunks for printing.

Having a built-in reference area to actual dmax and paper base white right there on the sheet is genius. Something to consider adding to my next version of the tool