terraPin ACME 6X6 (6x9, 6X4.5) Pinhole Cameras - 120 film

by schlem Aug 26, 2016
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hello! first off thank you for the design. Second, what film do you use? im super new to this and a push in the right direction would be nice.

I'm super happy to share, but I'm not sure exactly what you're asking, but I'll address my assumptions individually:

When you ask what film I use, I assume you are asking what film I recommend that YOU should use.

If you mean what "format" film this camera uses, it takes 120 film, also known as Medium Format.

If you want a specific recommendation, I have worked out exposure times for a number of films, including FujiChrome Velvia, Kodak Ektar, FujiFilm Acros, the Provias... See the exposure charts for more information on tested film stocks.

If you're asking what film I, personally use, I shoot a lot of Velvia slide film, Kodak Ektar, and Ilford PanF+. These are my favorites, but you should eventually shoot enough film to decide which are your favorites!

Let me know if you have any questions about this.

Congratulations for the work! it's awesome!
Would it be possible to post a self-clipping slider set for the ACE too? That would be great! Otherwise I will try it to do it myself :)
Thanks a lot!

Done. I haven't tested, but it's based on proven designs. Let me know how it works!

To be honest, I was putting this off, unless someone asked for it. :)
I should be able to adapt the modification I made to the OSKAR sliders without much difficulty.
The OSKAR is a better camera, in many ways, but maybe you're interested in the ACME/ACE/CAMEO for the licensing? Perhaps the snap-together construction? I'd be interested in your perspective.

In any case, I will endeavor to get this done in the next week or so. Don't hesitate to remind me if you don't hear from me. I'm easily distracted.

Just chose to build the ACE as I want to take 6x9 pictures and seemed to me the most documented project so far. At the same time I wasn't able to see the self-clipping slider for the OSKAR, nor the OSKAR Tuxedo. Is that right?
That iteration on the slider is for me a good upgrade as you don't need an extra-piece to secure the camera, which in my case I can imagine it would be easily lost :(

This is by far the COOLEST 3d printable thing I have EVER seen! And that's saying something!

Very kind words! I hope you print one. Let me know if you have any questions!

I do infact have a question: If I were to design one myself as a student, what would be some mistakes to avoid etc?

Good Question! The first consideration I would suggest for a camera is material / opacity. I started with black ABS, which is colored with pigment and naturally opaque. Everything about the material is good for a camera application, but the finicky nature of its "printability" and toxicity moved me to PLA. Finding opaque PLA wasn't a problem (or even a thought), until suddenly the supply of black PLA I had in the Schlaboratory was found to be translucent, even though it was called "Black as Midnight". Apparently, in the cut-throat realm of the 3D printer filament industry, coloring the product with a dye rather than a pigment (formed from colored solids) was deemed financially prudent (even though I suspect the margins on the product are princely). And the vast majority of users of the product have no requirement for absolute opacity. I obtained some other polymers to try, but many are crazy-expensive, erosive to non-hardened nozzles, or simply not opaque. My standard is ZERO light through a 1mm sheet of printed filament, with the brightest light I can find behind it. Currently, I am using eSun Black PLA, and it works flawlessly.

Beyond materials, avoiding light leaks that will destroy your exposures is Job One. Essentially a box with a tiny hole, your task as designer is to invent a way to open and close that box, and advance (and possibly rewind) the film, such that the joints and tiny gaps don't let ANY light into the box. That, alone, is one reason that black is a traditional color for cameras. A typical camera light trap requires stray light to change directions three or four times before it can shine into the camera. Any bouncing light gets absorbed, rather than reflected. For parts that fit/slide together, I find that a 0.5 mm tolerance works well with most FDM printers.

TWO KNOBS. So many reasons.

Another thing I would suggest is that 120 film is always going to produce MUCH nicer photographs than 135 (35mm). Also, dealing with the indexing numbers on 120 film is better than most of the indexing options for 135. But, if you want a real design challenge, a 35 mm pinhole camera that works as well as a 120 camera is a lofty goal. I think I designed one, but the fiddly nature of assembly negates the other virtues of the design, IMO.

Also (I'm guilty of this), documentation of some sort is key. Some people will look at the STLs and the pictures of your camera and intuit how it all goes together, others... not so much. I try to make good faith documentation and then be very responsive to questions, for unanticipated questions / misunderstandings.

That's just a quick brain dump. I hope that helps. Don't hesitate to hit me up with any questions you may have in the future.

Thanks! I'll put the information to good use. (This was incredibly helpful :D)

THIS is how I do it. Don't be in a rush, and use the smallest beading needle you can find. It's actually not the most critically important factor in making a pinhole camera. But knowing how big your aperture is, is important.
Your f/# = focal length / aperture diameter

Hope that helps

Awesome! Thanks!

Hi there! Printed this yesterday and am very excited to get some film and try it out. Silly question, but any tips for making the .22mm pinhole?

Hi, could you tell me which parts absolutely need to be opaque? thank you for the design!

There are not that many, but it's probably easier to tell you that, of all the parts, only the knobs and winders DON'T need to be opaque.

Another question! In the first picture the camera features what appears to be a clip to hold the cap tightly closed in place, but I can't find it among the thing files. I found a similar thing uploaded to the OSKAR... Is it compatible with the ACME?

Yes! The 6X6 OSKAR and ACME share the same dimensions where that clip fits. It is an optional part, necessary if the sliders on your camera are excessively slide-y. A bit of gaffer tape works quite well, too - and won't get knocked loose in your bag. I have recently worked out a self-clipping slider set. If you haven't printed that part yet, I can modify the ACME sliders so that you won't need a clip. So many projects! Let me know if that would be of interest!

I was planning on printing the cap in a few hours when the body I've modified finished printing, so any improvement would be greatly appreciated, of course! :D

OK! DONE! There is a new source file, called "terraPin_ACME_Better_Cap_Plate.stl" that incorporates a built-in snap clip into the sliding parts. It will fit all ACME 6X6 body variations. Much better than the arched clip or a bit of tape!

Wow, that was FAST!! Thanks a lot, I'll be sure to post pictures when it's done :D

Hi! First of all, congrats on the design! I love it :)

I was just wondering if there is a reason for the tripod mount not being a blind hole so you don't need to put tape on the inside. Wouldn't it be better like that?

Absolutely. I have had that very idea, but I worry that there won't be enough thread for many tripod screws.

In many cameras, I also use a 1/4-20 flanged nut for the tripod thread, which works fantastically. Folks sometimes have a hard time finding the hardware, though. I recently designed a 3D printed replacement for the 1/4-20 flanged nut, which pops right in, and is replaceable if it gets stripped out. I should rework the ACME family of cameras to use this part.

I just made a very rough modification of your design and published it as a remix: https://www.thingiverse.com/thing:2824605

Terrapin ACME with blind tripod thread


I was also wondering how should I put the tape in the hole in the back so I can see the frame numbers but the light doesn't affect the film. I really don't know what you mean by "Holga flap", sorry. Maybe you could post a picture of what you mean by this?

The "Holga Flap" is a bit of gaffer tape that covers the frame index hole. It probably isn't strictly necessary, but light leaks suck. There is a 14 ? mm disk of red(ish) translucent material INSIDE the camera body, recessed in the wall behind the film plane. I 3D print mine from translucent red PLA, but you can use a plastic file folder from an office supply store (like $0.99). Make sure you can read a dollar bill through it.

OK. It makes sense now. I thought that the Holga Flap was meant to be on the inside of the camera and in my head it completely ruined the purpose of having an index hole haha

Thanks for your replies!

what is the 14 mm red disk , what did you use?

Hi mattknapp

120 film is indexed by advancing the film until the next frame number comes into view. The 14mm red disk gets glued into a recess inside the camera for viewing frame numbers. These days, I print disks from a red translucent PLA, but a clear red presentation folder (think Office Max) works too. The red is a traditional color for this little viewing pane. The camera is designed such that stray light from the window probably shouldn't affect your film, and the pane is probably not strictly necessary. I cover the window with a bit of gaffer's tape on the back of the camera, as I often leave a given camera loaded with film for a while and I want to avoid fogging my exposures. HTH! Todd

can this be adapted to 35mm film?


my friend Clint O'Conner has designed an adapter that allows the use of 135 film in cameras that take 120 film.

Of course, you lose the ability to accurately index your frames, and should, in fact, tape the sliding cover for the frame number window in place to avoid ruining your photographs. I get that 135 film might be easier to source and process sometimes, but with the Internet, you can buy film online and send it to remote labs for processing. I promise you that 120 film makes better pinhole than 135, by virtue of the larger frame size.
Hope that helps.

35mm Film on 120 Spool

If there are awards for this kind of thing, you should get at least three!

OMG...stunning! a gift to the world, thank you so much!!!