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.

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.

• Wikipedia, always a good resource for overall info and related topics; http://en.wikipedia.org/wiki/Pinhole_camera
• A fantastic resource with in-depth discussion on all the topics related to DIY Pinhole: http://www.davidrichert.com/pin_hole.htm
• Another site full of info: http://www.pinholeday.org/
• A site full of fantastic pinhole design tools and calculators: http://www.mrpinhole.com/index.php
• A fantastic way to get inspiration on pinhole cameras is by searching "DIY pinhole" or a similar phrase on Flickr.

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.

Comments

[AlexG401]

Hello Matt,
First of all, congratulations for the excellent article, is helping me a lot to understand all the science behind the camera.
I'm having a question in one of the calculations you present, could you help me solve it?

According to the formulas presented, the diameter of the image circle resulted very large. Using the calculator of the website Mr Pinhole (which does not explain each term, just presents the formula), the result is quite different.

I need to build a camera with 60mm focal length. The diameter of the orifice was calculated and resulted in 0.345 mm. The corresponding F aperture is 174. The thickness of the material where the hole will be is 0.1 mm, resulting in an angle of view of 147.7 degrees. So far, all OK. The problem now occurs in calculating the diameter of the image circle.

The formula you present is id = 2 x fl x tan (av/2), where: id = image diameter, fl = focal length and av = angle of view. By applying the values, already known, in the formula, the result is 414.4 mm in diameter of the image circle. The MrPinhole has the following formula: image diameter = focal length x 1.92, which results in 115.2 mm as the diameter of the image circle. As you can observe, the results are quite distinct, which led me to this doubt.

If you can help me, I'd be grateful.
Kind regards from São Paulo, Brazil.
Alex Gimenes

[mattthegamer463]

Hi, I think the differences are due to Mr. Pinhole using a subjective approach. Notice he doesn't account for material thickness, just focal length and an arbitrary 1.92 factor. Consider a pinhole viewed from the side, it appears not as a circle but as an oval. Eventually it stops appearing as an oval as the material thickness obscures all light passing through. As the oval shape shrinks, less light reaches the film at that angle, making a darker image. Thus the usable area is not the same as the maximum image circle as the amount of light at that edge is 0. Whether you use a curved film plane also plays a role in the light intensity due to the inverse square law.

I hope this helps you understand the difference. Don't attempt to use the entire image circle as the outer portions are effectively useless, but it gives you an idea of the possible coverage area and you make your decision based on how much vignetting you are willing to accept.

[AlexG401]

Hello Mat

Everything's clear, now.
Thank you so much for taking your time replying my message.

Kind regards,
Alex

[Sibgetullah]

hello, I have read your article by translating it with a dialing program and I would like to say that I found it very useful and I like it. But there's a place I can't fully comprehend. Can we use this pinhole camera with 35mm film? I didn't understand English very well. And the calculations you made (f-stop, diaphragm ..) Is suitable for 35mm films? That's why I'm going to use 35mm film. Thank you again for your article

[MichaS5]

If I just take your design and make it less wide will that be suitable for 135 format? Great instructable by the way, excited to try it

[mattthegamer463]

Yes you can change the design for 35mm. Glad you liked it.

[AarónA127]

I just want to congratulate you and thank you for this fantastic tutorial. There's a lot of knowledge packed in those lines!!.

I tried a basic 35mm pinhole camera and just love it, and learned so many things about photography thanks to this camera, but sharpness is not a word i would use to define its results. Then i realized that medium format would work much better. I was thinking in something a little bit less extreme, like 6x14, with an angle of view maybe just a little bit over 120º, maybe multiformat, so i can try other medium format sizes. I made several diagrams trying to achieve a proper arc, the right length of film, the right focal length. I am still a little bit confused with the interrelations of these measurements. 65mm focal lenght seems too "zoomed in" for me, but at the same time you need that radius to make a proper arc, and still you're getting an angle of 150º...

Anyways, this tutorial helped me so much to change some things in my design (not finished yet). I love the shutter you made, and overall is a really clever design, so thank you and congrats again

[mattthegamer463]

Thanks for your comment, I'm glad things are working well for you and that I was able to teach you something.

[TimW118]

Got to tell you that this is one of the best pinhole tutorials I've found. Started off by wanting to adapt a 6x4.5, 6x7 film back (or even a 4x5 film holder) for pinhole. NOW I want to make a curved focal plane camera. I'm only worried about how to keep the film tight to the "pressure plate" guides without pulling it too tight and flexing it across the wrong axis. Also, keeping the spools tight enough to not unwind, but loose enough to move easily.

[mattthegamer463]

Thanks, I'm glad you liked it. I did my best to teach the reader how to apply the principles, rather than copy my camera exactly.

Since pinholes have a huge depth of field, they also have a huge DOF at the film plane, compared to a regular camera. Pressure plates and precise location of the film isn't a big deal. That's why you can get away with decent images in a pinhole camera with a flat focal plane, where the film is a different distance to the pinhole from the centre to the edge. The curve helps get it near to the right place to improve light falloff and reduce vignetting, more than anything.

I would recommend you don't worry too much and keep the film loose. My spools are pretty much loose too, and I relied on the felt I am using as a light seal to also serve as the friction material which keeps the spools semi-rigid in place. I just pressed down the knobs with some force before tightening the set screw, to create friction on the felt. It works great. Even if they were loose I don't think they would have any interest in moving when not being touched so I wouldn't worry about it too much. You can always test your mechanisms with an old backing paper from some 120 film. I had never actually shot 120 before and had no access to a paper backing or wasted film so I sacrificed a whole fresh roll for the testing purposes.

[Bryan2200]

Hey. Thank you for the great tutorial! I would definitely vote for you if I hadn't done so already!

I have a question regarding the knob and internal film mount. Do you perhaps know the equation to work out how big a turn would have to be to switch from the exposed film frame to the next blank one? I would like to place markings on top. Does that make sense?

[mattthegamer463]

Hey glad you liked it.

What you're trying to accomplish isn't really possible with 120 film. The reason for the sight windows on the back of the camera which are used for frame alignment are due to the issue of the changing diameter of the taken-up film. 35mm uses the sprockets and a little toothed wheel to keep track of film movement, but there are no holes in 120 film. Some 120 SLRs use a little wheel which rolls on the film to keep track of the movement but it is a pretty delicate and complex system. The sight windows on the back of the camera are much easier, simpler, reliable and practical, its what 98% of 120 film cameras have done for over 100 years.

[bonzier11]

I'm attempting to make a pinhole camera but instead of 35mm i'm going to use polaroid pack film. because i'm using pack film I cannot make a curved film plane. luckily the pinhole diameter and film size (and all that other junk that i figured out with the handy mr pinhole website calculator) makes the angle of view 70 degrees. so heres my question, is it better to put the film plane in the center of focusing zone (the center will be at 70mm instead of the correct 90mm) and will be in the perfect focal length closer to the edges of the frame. or would it be better to place the center of the image at the perfect 90mm and let the edges of the image blur outward? Do you think that either would produce a horrendously blurry image? Or will the image stay mostly in tact? I purchased a laser drilled pinhole so that shouldnt cause any problems. are there any simple solutions to my problem that i'm over looking? any help is much appreciatted, thanks in advance!

[bonzier11]

also, how far off can the film be from the correct focal length, and still produce a good image?

[mattthegamer463]

The film plane depth of field (which is the same concept as the image plane depth of field, just on the other side of the lens) is pretty wide with a pinhole. The f If you split the difference and put the film so the calculated focal length is in the middle of the film's width, you should get good results. If I were you I would try to build in some adjust-ability so you can move the film (or pinhole) closer and further if you don't like the results. If you have a blurry spot in the middle it would be less visually appealing than if you had a blurry edge.

See what you can do about leaving 10-15mm or so of adjust-ability in your pinhole to film distance so you can correct it if you don't like it. Example; if you mounted the pinhole on some 3mm thick material and had it on the front face of the camera made of 3mm thick material, you could move the pinhole from the inside of the camera to the outside and also flip it around in each position, giving you a D=0mm, D=3mm, D=6mm, D=9mm, but it would be fixed in place by screws at any of those spots.

Otherwise, I would maybe put the center at 85mm and let the rest be where it may.

[ModestOrange]

I love this instructable! It made me build two! One of your design and a second of my own. But I cant seem to get the spooling down. The film keeps buckling when I spool especially when the film tried to make a turn into the guides. I have tried to use tape as suggested and in the second design I planned for this and sanded and burned the guides to try to relieve the friction caused by the curvature of guides and rods. Might you have insight into how to solve this problem?

[mattthegamer463]

I added some polyimide "kapton" tape on the wood where the film would touch to reduce friction. Any tape which is smooth to the touch and sticks well to the wood should work to help reduce friction. Also if the turns are too tight, especially where the film makes tight turns, try using a larger diameter of wood dowel.

[talirc917]

This is incredible!! Very well designed. I am doing a project like this for school, and you have helped me immensely. I have a couple questions though, if you don't mind helping me out.

Do you have any way to see the film count so you know when you've used all the film?

Why do you have two dials for the film advance? Do you turn them at the same time?

I can't find a pinhole in brass shim shock like you did. Do you happen to have a link to a place where I could get one?

Thanks so much!!

[mattthegamer463]

Hey there,

You view the film count through the little swivel door on the back of the camera. You can also make a little red window instead of just a hole with a cover.

The two dials are because there is too much friction on the film so it has to be loosened from one end and pulled through with the other as you advance. It also lets you adjust it backwards if you crank it too far forward past your number. It also lets you tighten the film so it isn't too loose.

I bought mine from this guy:

http://www.ebay.ca/itm/0-3mm-Laserdrilled-Pinhole-...

His prices have come up but the product is good.

Good luck with your camera.

[giocad]

you're fantastic!
I want to build one as beautiful as yours.
you're really a good manufacturer.
10 votes