Introduction: Design and Build Your Own Pinhole Camera

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If you're somebody who likes to take film photographs, you know the satisfaction you get from a film photo that you just don't feel when you use digital.  Just imagine seeing the first photo you get out of a camera you designed and built yourself!  It is a fantastic feeling that you absolutely must experience!

The process of designing and building a camera may seem daunting, but with a little patience and the help of this Instructable and some further reading, you'll be able to do it.  You can use this information to figure out what you want to build, gather some simple materials and tools, and build it!

I want it to be clear that building a pinhole camera relies on your abilities, available materials, and your desired outcome. As a result, this Instructable is less of a step-by-step and more of a lesson on how pinhole cameras work, the physics involved, and some practical knowledge I gained while researching and building my own camera.  I'll do my best to answer any questions but please try to keep this in mind when reading;  thinking and problem solving are required.

Step 1: What Is a Pinhole Camera?

First thing, what is a pinhole and why does it have optical properties?
A pinhole has the ability to function like a glass lens because it excludes all light rays which are not reflecting off the subject that the camera is pointed at.  When light hits an object, it is scattered in all directions; this is why the object is visible from any angle.  If all this light was entering a camera and hitting the film, no image would be produced.  The light needed for a photo has to be aligned to make a focused image.  The pinhole excludes light rays from all irrelevant angles and only allows through rays which are almost perfectly aligned from the subject through the pinhole to the film.  See the image above. The red lines are light rays.  Note that they cross at the pinhole and produce an inverted image.

Applications of this phenomenon; the pinhole camera
First used in both ancient Greece and ancient China, pinhole cameras are a form of camera that takes images without using a conventional optical lens.  Originally called a "camera obscura" they were large boxes or rooms which had a hole in one wall.  This hole formed a sort of lens resulting in a projection on the opposite wall of the scene outside.  Someone inside the camera would then place a piece of paper on the wall and trace the projected image.  Once photo-sensitive materials were discovered and film was invented, the design was miniaturized but the concept remained the same.

A basic pinhole camera is a light-tight container with a tiny hole at one end, and a piece of photo-sensitive material at the opposite end.  Light passes through the pinhole and the photons cause a chemical change on the film, resulting in an image being produced.  Since the pinhole is very small, the light passing through it is light which has a particular direction; it is heading directly at that pinhole from the subject, and at a certain angle that it can pass through the pinhole.  All other light from the scene does not reach the inside of the box.  If all the scattered light that might happen to fall on the film was allowed, no coherent image would be produced.

Some terminology:

Pinhole camera:
A camera which utilizes a pinhole instead of a glass or plastic lens.  The pinhole is quite literally a pin-sized hole in a piece of thin, opaque material. Usually sheet metal is used.

Depth of field: 
With any camera lens, the depth of field is the forward and backward distance from where a lens is focused to that is in focus.  On optical cameras, this is determined by the size of the aperture inside the lens.  In a pinhole camera, this is determined by the diameter of the pinhole itself.  The smaller the pinhole, the larger the depth of field will be.  The effect can be so pronounced that the foreground and background of an image can be in focus simultaneously.  This is something that even the best DSLRs can't do.

Focal Length:
The focal length is the distance an optical system takes to converge light.  It applies to pinhole photography as the ideal distance from the pinhole to the film.  It is calculated based on the diameter of the pinhole.  If the film is not the correct distance from the pinhole the image will be out of focus.  It needs to be as accurate as possible for the best image quality.

f-stop (aperture):

You probably already know what f-stop and aperture is and how to use it for conventional photography, but what is it really?  the f-stop value is based on the diameter of the aperture inside the lens compared to the distance from the aperture to the film.  There is a formula to calculate its value based on those two measurements, which will be covered in Step 3.

Reciprocity Failure:
Pinhole cameras need long exposures, and film does not respond to the amount of light they receive over long time periods in a linear fashion.   More on this in Step 9.

Aspect ratio:
The ratio between the height of an image versus the length.  For example, HDTV is normally 16:9 meaning the width is "16" arbitrary units and the height is "9" arbitrary units.  It is just to give a relative measurement of the final image shape, not the absolute size.

Step 2: Pinhole Camera Design, Part I

Designing the camera is a simple process if you know the steps involved, and the relationship between various measurements and calculations.

The smallest and most difficult to control element of the camera is the pinhole itself.  Making a tiny, precisely round hole in any material is very difficult.  It may be out of the realm of your capabilities, and if it is, that's okay.  Pinholes can be purchased from numerous websites and eBay.  Just Google the diameter of pinhole you need and you'll find some results.  I purchased one off of eBay that was exactly what I needed for about $7.50. A picture of it through a microscope is above.

If you want to make your own pinhole at home, a good material to use is the metal from the side of a pop can.  The thinner the better, as long as it is light-proof.  Use a pin and a hammer to gently poke a hole through.  Use an eraser or something soft to support the aluminum so it stays flat when being pressed on.  Use some 600 grit sandpaper to sand away the protruding metal on the opposite side.  If you have a microscope or a flatbed scanner you can inspect the pinhole roundness and quality. 

You need to know the diameter of the hole pretty precisely to determine the focal length and equivalent f-stop, so that the film distance and exposure times are correct.  You can also use a scanner to measure the diameter of a pinhole.  Simply scan at a high resolution, then use Photoshop or a similar drawing program to count the number of pixels across the hole.  For example, if the hole is 50 pixels across, and the scan resolution was 1200 DPI, the diameter is about 1mm.

You can also purchase tiny carbide drills for Dremel rotary tools that will do tiny precise holes like the one pictured above.

Step 3: Pinhole Camera Design, Part II

Determining the focal length based on the pinhole size:

Once you have a pinhole created, you can determine the distance the film needs to be placed at to get a clear image.  The formula is:

focal length = (pinhole diameter / 0.03679) ^ 2  , units are in mm.

Example:
focal length = (0.3mm / 0.03679) ^ 2
focal length = (8.17438) ^ 2
focal length = 66.49mm 

Therefore, with a 0.3mm pinhole the film should be placed 66.49mm away from the pinhole.  I rounded to 65mm for my camera, and inaccuracies are bound to happen, but as long as you are within a few millimeters then the results will be good.

Determining the f-stop (aperture) equivalent:

The f-stop value is a relationship between the diameter of the pinhole and the distance to the film.  The formula is:

f-stop = focal length / pinhole diameter

Example:
f-stop = focal length / pinhole diameter
f-stop = 66.49mm / 0.3mm
f-stop = 221

This value will later be used to determine exposure times based on measurements from a light meter or another camera.

Determining the view angle:

Fig. 3 shows the maximum angles light can be traveling and still get through the pinhole
Fig. 4 shows the "cone of light" passing through the pinhole

Since the pinhole is round, the light passing through it forms a cone-shape on the inside of the camera.  This cone must be wide enough to cover all the film at the correct focal length.  The factor that affects the angle of the cone is the thickness of the material the pinhole is made of.

If the material is too thick, it becomes less of a "hole" and more like a "tunnel", resulting in the camera producing an image like looking through a tube.  No good. The material needs to be as thin as possible.  Some good materials are aluminum can sides, shim stock, or feeler gauges.

Trigonometry can be used to calculate the view angle that a particular pinhole diameter and material thickness offers.  Fig. 5  shows the triangle used to solve for x. 2x is the angle, in degrees, that the camera is capable of seeing.  With this angle and the focal distance then you can calculate the diameter of the image that you can take.  Fig. 6 shows the triangle used to find the diameter of the "cone of light" at the correct focal length. 

If this diameter doesn't cover your film, there are a couple tricks that can be used. This is covered in Step 5.

Step 4: A Word on Film

As you may know, there are many types and sizes of film that have been produced in the last century.  Due to the rise of digital photography, very little of those film types are still available.  35mm (135) is the most common type, with its dual perforated edges.  The standard photograph size for 35mm film is 36mm wide by 24mm tall.  It is still widely available at stores and on the internet, and development services are still available at department and drug stores.

Medium format film is much larger. The standard medium format film that is still available is 120 film.  Medium format images can be 6x6cm, 6x9cm, 6x12cm, or 6x17cm.  Medium format can be tricky to work with because it comes rolled on a spool instead of inside at canister like 35mm.  Something important to note with medium format film, however, is that it is paper-backed and numbered, and these numbers must be followed when rolling because the diameter of the supplying and take-up spools change as the roll is used, so the film position cannot be known by counting the number of knob turns.  A small window with some sort of hatch or door must be installed to allow the user to view the back of the film while minimizing the amount of light that gets in.  More on this can be seen in images on Step 8.

Which is right for me?

Now that all the major math is done, thought can be taken to determine what kind of film this camera can use.  If you used a very thin material and a relatively large hole size then you might be able to cover a large 6x6cm image size, and medium format film may be a good idea for you.  If you want to do panoramic images, I recommend this.  Just be sure you have development facilities for it!

If your pinhole is very small (0.1-0.2mm approx.) then the image probably won't cover a 6x6cm square without severe vignetting.  A 35mm standard frame or wide-angle would be perfect.

Developing:

An important thing to think about is film development.  If you develop your own film, you can probably be flexible in your choice of 35mm or 120 film.  If you are relying on a local photolab for developing, go in and ask if they do 120 film.  Many places don't take it any more, or they mail it out to be developed and charge you a lot of money.  Make sure you have your development situation understood before embarking.  You don't want to build a camera you can't use.

Step 5: Pinhole Camera Design, Part III

So at this point you should have a pretty good understanding of how to get a pinhole, how to measure it, how to determine the focal length for that pinhole, and the image diameter for that focal length.

That's the end of the hard math.  Its almost time to get back to the real world.

Curved Film Planes:
As I get into the camera that I built, you'll notice the film rests on a curved piece of wood so that itself forms a curve, and you might be wondering why is that?

The reason that I built a curved film plane camera is because the pinhole I bought produced a 150 degree image.  This is huge, and as a result, if the film at the center was at the required 65mm focal length, the sides would be off by tens of millimeters.  The image would only be in focus for the very middle of the image, and this is unacceptable.

Using a curved film plane maintains the distance from the pinhole to the film across the whole 150 degree viewing angle.  The entire image comes out in perfect focus!  This can be done for any size of image, but it is an especially useful technique for panoramic medium format cameras.  The 6x17cm image really can't be done by any other means.

For 35mm using normal framing size, or 6x6cm medium format, the curve is not necessary.  There will be minimal benefit so it isn't necessary.

The Box:
Obviously, this pinhole and film all need to go into a box.  You can make your own box from scratch out of any kind of light-proof material, or you can build the camera out of a preexisting box.  Make your selection based on your film choice and image aspect ratio.

The box is all about having control of light. When film is in the camera, the only light we ever want going in there is through the pinhole, and onto the film.  Nowhere else, otherwise we will end up with streaks of overexposed spots on the film.  Sealing the box isn't difficult.  Electrical tape can be used for cracks and edges, and felt or foam can be glued on to seal the removable opening.  Try to pick a box that is relatively light-tight to begin with to make this job easier.

You're going to have to figure out a way to keep the film in place as it transfers from one spool to another, or from the canister to the take-up spool.  The easiest way to do this is to have a piece of flat material in parallel with the pinhole, exactly the focal length away. This will serve as a sort of pressure plate for the film, to keep it flat. Then mount the spools on either side of this piece, so when the film is run across from one to the other, it will be held flat across this plate.  Other methods exist so see what you can come up with.

Attached files:
If you would like to make use of my design as a starting point there are PDFs and a DWG attached that will let you reproduce 1:1 cutting guides or laser-cut your own pieces.  Just note, most of the holes and markings are not included.

Attachments

Step 6: Building Your Camera

Here comes the hands-on.  Time to build your camera.

There's lots to do.  Youll need to mount your pinhole on the "front" of your box, drill holes for the film spool knobs, mount your film plane, drill a window for reading the film numbers.  There's lots to do that is very design-specific and unique so I'll leave the problem solving to you, but take a look at what I did for some ideas if you need them.

If you need additional inspiration, go over to Flickr and search for "DIY pinhole" or a similar phrase and take a look at all the cameras people have built, and their photographic results.  Its a fantastic way to figure out what you want to make.

Here's a tip that will save a lot of time fiddling, and help you stop worrying if your camera is going to work or not.  Buy an extra roll of 120 film and sacrifice it as a test roll.  Use it to test the rear window number alignment, the film advancing, and loading practice.  You'll also need a empty spool to serve as a take-up spool for your first roll, so you can use this one.

I built my camera from scratch using 1/4" poplar planks purchased from a local hardware store.  A solid wood glue joint is plenty light-proof but I ended up putting electrical tape in all the internal corners just to be sure. You can drill a shallow hole and glue a 1/4-20 steel nut into it to use as a tripod mount.  1/4-20 is the ubiquitous tripod thread and a very common nut size.

For film knobs I got some 1/4" diameter aluminum rod and filed down the end to match the diameter of the 120 film spool.  Then I drilled a hole and forced a wood screw into it.  I cut off the head to make a perfect spool-turning key.  I filed a notch around the aluminum rod to use with a retaining ring, this will stop the rod from being pulled out of the top of the camera.  The knob on the other side will stop it from falling in.  If you have a lathe this part will be much easier to make.  See images above.

If you are using 35mm film, you will need to make a take-up spool instead of a peg for a empty film spool.  Use a piece of dowel or metal rod and attach some sort of catch point that a sprocket hole can be caught onto.  That way the film can be rolled onto the take-up spool and unrolled back into the canister when finished.

Step 7: Building Your Camera, Part II

To hold the bottom of the camera on I made some small L-brackets out of aluminum sheet metal.  Store-bought brackets are a good idea too but they'll need to be threaded so that screws can be put in to hold the camera shut without rear access for a nut.

Shutter:
Your camera is going to need some way to stop light from entering when you aren't taking a picture, but get out of the way easily when you do want to take one.  One way to do it is to mount a UV filter and use a standard lens cap.  You can even just cover the pinhole with a piece of tape.  I decided to build a full-on shutter mechanism with a spring return.

I mounted my pinhole on a piece of aluminum that is held in place with four machine screws, which also hold on the shutter mechanism. A problem with extremely wide angle pinhole cameras is that they are difficult to cover and uncover without getting in the way of the light.  I built a shutter out of thin sheet metal that sits on the inside of the camera.  The shutter moves by being pushed up with a shutter release cable.  The shutter returns to the closed position by a small spring mounted on a smooth metal standoff.  See pictures and captions above.

Step 8: Finishing

Once the camera is built and the mechanics tested, the inside needs to be painted black.  The film is reflective and some light could reflect off the film and around the inside of the camera, causing image defects.  Use a matte black paint if you can to absorb the most light possible.

If you made your camera out of bare wood, you'll want to finish the exterior with a stain and lacquer to protect it from rain or anything it might encounter when outside.

If the film is sticking in the camera due to friction, as mine was on the wooden guide posts and along the guiding edges, apply some smooth tape to help reduce the friction on those surfaces. Packing tape and scotch tape work well.  You can see the kapton tape I used in the images above.

The opening face should be sealed with some sort of adhesive foam or felt, if the box is not perfectly light-tight to begin with. 

The rear viewing hole should be rimmed with some felt to keep light from entering.  The back of the film should be isolated so that the numbers can be read without excess light entering the camera body.  See above:

Step 9: Loading and Shooting

Calculating f-stop:
Previously we calculated the f-stop value of the pinhole. The formula was f-stop = focal length / pinhole diameter.  My f-stop is 221 so I will use this as a sample value to determine the information we need to calculate exposure times.

Exposure time:
Obviously, no other camera or meter is going to allow f221 as an option, so we need to make some calculations to find out how to do an equivalent exposure time from something that we can measure.

f-stop values have certain cornerstone values, and the difference between these values is that the amount of light allowed through is halved each time.  Essentially, the area of the circle formed by the aperture is halved each time, and thus the light.  These values are as follows;  1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, 44, 64, 88, 128, 176, 256, 352.  Anything past f22 is going to be unavailable on a light meter, so here's how we are going to determine a multiplication factor for the pinhole;

Pinhole exposure is not an exact science, so precise math is not required.  This is the kind of thing you'll have to calculate out in the field, so doing it in your head semi-accurately is acceptable.  No need to bring a calculator.  So, if the pinhole is f221, lets round to f256 to make life easier.  If we count backwards to f16, there is a difference of 8 values.  This means the amount of light through an f16 aperture is 28 times more than f256.  This just so happens to be 256.  This means that when we take a digital camera or light meter, set the ASA/ISO to the speed of the film in the camera, set the aperture to f16 and get a shutter speed, we multiply it by 256.  For example, if we measure a value of 1 second, we will need to expose for 256 seconds to get enough light.

Reciprocity Failure:
If all that calculating seemed straightforward, unfortunately its more complex than that.  When exposed for a short period of time, film's response to light is linear.  Expose the film for twice as long, and the film will react twice as much to the light. However if you begin exposing for more than a few seconds, the film stops responding linearly.  It actually takes a lot more light than you would expect.  This is called reciprocity failure and it happens with all film.  The solution is to use a chart to estimate the extra time needed.  There is one attached above and can be printed out and brought with you when shooting until you have enough experience to make estimates without it's help.

Using the example of a 256 second exposure, the reciprocity factor is approximately 4x for that length of exposure, so 256 seconds turns into 1024 seconds.  4 minutes to 17 minutes, what a huge difference!  Of course, this is all just for "ideal" exposure.  A few minutes less, or more, won't hurt anything.  In fact, I exposed my first test roll (which you can see on the next step) only 1/8th as long as I was supposed to and it came out looking pretty good.

Tripod Use:
Because pinhole exposures are always much longer exposure times than normal cameras, you will absolutely need to use a tripod or rest the camera on a table, fence or some other stable stand.  Opening and closing the shutter should be done without disturbing the camera, ideally, but if done quickly they will not affect the final image.  Moving the camera mid-exposure will result in a double exposure effect.

Step 10: Results

After your roll is shot, get it developed (or develop yourself) and check out your images!  Hopefully they came out great.  If you have a flatbed with a transparency attachment or lid, you can scan them at high resolution yourself.  This is what I did.  Since most flatbeds can't scan 120 film by default you may need to scan it in two halves and re-assemble in Photoshop, this is what I did and it worked great.

Take a look at my photographs above. I have uploaded the high-res for you to inspect closely.  You'll notice the large white streak on the left side of the images, that is a light leak through the foam seal at the bottom of my camera.  The importance of sealing!  I think I have it fixed now but I won't know for sure until the next roll of film.

Hopefully I have made sense throughout this long Instructable.  Feel free to ask any questions by comments or message to me. Please let me know if I've made any mistakes so I can fix them.  Check out the next step for more reading on the subjects presented here.

Thanks for reading!

Step 11: Very Useful Links

I don't actually know anyone in real life who has done pinhole photography.  I learned everything from the internet and pieced it all together.  Below are the best resources I've found and are a great place to get some more info.

Step 12: More Pinholes of Mine

Since this Instructable I have done some more pinhole cameras (aside from my anamorphic pinhole https://www.instructables.com/id/E5DNVGKHD4VMCZ5/ ), here are some of the results.

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