Digital Pinhole Experiment

pin holeThis past week I spent some time on a long overdue update to my website – www.forestrat.com. It’s nothing fancy. I’m no graphic artist so I keep things simple.

In the meantime I have also been experimenting with turning my digital SLR into a pinhole camera – Wikipedia.

In earlier posts I mentioned that it has been known for centuries that passing light through a small hole in one wall of a box will project an image on the opposite wall. This is known as the “camera obscura”. Photography was born from the desire to “fix” this image permanently without the need for someone to trace the image by hand.

A pinhole camera is basically just a box with a hole in one end and a light sensitive surface on the other side. It can be built out of all sorts of materials – shoe boxes, oatmeal boxes, tin cans, etc. as long as it can be made light tight. A gigantic one has even been made out of an entire abandoned air plane hangar – The OCRegister.

The tricky part is making a good pin hole. The hole needs to be very small when working at digitial camera body scale and it needs to be perfectly round without burrs. I searched the web for some guidance and ended up basically following the method described here – DIY Pinhole for dSLR.

I drilled a quarter inch hole in the center of an old camera body cap and used electrical tape to attach a piece of metal cut from a soda can with my pin hole in it. I made the hole using a pin saved from the packaging of a dress shirt.

I made several pin hole “lenses” trying to get the hole just right. I also tried using aluminum foil instead of the can metal. The foil was much easier to puncture and was much thinner, but it was also more delicate and took a steady hand to make the hole without tearing. I ended up preferring the foil once I got the hang of it. You can purchase laser cut pinholes from photo supply stores, but that takes away the DIY aspect of the whole deal.

Theoretically a pin hole lens will have a huge depth of field. Depth of field tells you where objects in a scene will be in focus. Setting your camera lens to f/2.8 will give a shallow depth of field which means that only those objects close to the same distance from the camera will be in focus. Nearer and farther objects will blur. As you reduce the aperture, depth of field increases. At f/22 (the limit for my regular lens) more objects front to back will be sharp. My pin hole should give me around f/168.
glass lens
Although a pin hole lens will give you great depth of field, don’t expect razor sharp images. Producing a perfectly round smooth hole isn’t easy and deviations will cause interference. Also light does funny things when traveling through a very small hole causing diffraction patterns. The size of the hole depends on the distance between the lens and the film (the focal length). The short distance between lens and sensor on my camera requires a really small hole; something along the lines of .298mm or .012 inches. Images therefore tend to be soft. If I had a box with a much longer focal length, the hole could be larger and things would be sharper.

Exposure times in bright sunlight were on the order of five to ten seconds and required guessing since the exposure meter in the camera would not work under these conditions. The view finder was tough to use too since the scene was really dark – in bright light I could make out major landmarks, but in lower light conditions forget about it. Trial and error is the order of the day and digital makes this much easier. I would have ruined a lot of film otherwise.

The two waterfall images  show the difference between a conventional lens and a pin hole. The first image was made with my aluminum foil pin hole lens. The exposure time was ten seconds which produced the silky smooth water effect.

The second image is the same scene made with a conventional lens. Stopping my lens all the way down to f/22 still required a shutter speed of 1/1250 of a second thus freezing the water as it fell.

I like this pin hole image. On the other hand, I tried it on other things and was not as happy. Closer more detailed scenes were too blurry for my taste. Below is a test image I took of a deck post.

pin hole

It is amazing that a shot this good can come from such a crude device, but the fuzzy feel just doesn’t work for me. I don’t mind misty images of lots of flowing water, but I tend to like the solid objects in my images to be nice and sharp. Picking the right scene is an important step in pin hole photography.

While messing around with pin holes, I ran across this little piece of equipment – the Loreo Lens in a Cap. It contains a fixed focus lens that fits on your camera sort of like a lens cap and offers f/5.6 all the way to f/64. It isn’t really a pin hole, but setting it to f/64 should be interesting.

It only cost fifteen bucks so I bought one. I’ve taken a few test shots, but nothing useful yet. I’ll give a full report once I have time to play with it under the right conditions.

MDW

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11 Responses to “Digital Pinhole Experiment”

  1. Cutthroat Stalker (Scott C) Says:

    f168? Wow!

    I like the softness. I especially like it on the sample photos from the DIY site because they are in B&W. I’m a sucker for B&W anyhow, but I think the softness lends itself more to B&W–for some reason it seems artsy in B&W but just blurry in color. The waterfall is great! I would imagine things with movement (leaves in a breeze, waves, etc.) might be fun to do.

    Looking forward to the Loreo shots.

    -scott c

    • forestrat Says:

      It is amazing how much an image can change just by removing the colors from it. The mood and focal point can shift a great deal. Black and white is all about form and shape.

      The geometry is still there in a color photograph but sometimes it is hard to see – your eyes can break the image up by color regions rather than just physical boundaries. The colors can draw your eyes off to a different part of the image. A color image is more complex and therefore the point can easily be missed.

      MDW

  2. fencer Says:

    Oh fantastic… this is so great. I’ve been wanting to experiment with this too, and I read somewhere about using a lens cap on digital cameras, but I couldn’t find the references again. Thanks for the links!

    Pinhole images have such an intriguing quality. They remind me a little of the sfumato style in painting which I’m playing with too.

    Regards

    • forestrat Says:

      I was not familiar with sfumato. I’m glad to learn about it. Surprising that it was used by big name artisits like da Vinci and I hadn’t heard of it before. You learn something everyday.

      Homer: “But every time I learn something new, it pushes out something old! Remember that time I took a home wine-making course and forgot how to drive?”

      Glad I could help get you back to the pinhole stuff. Make sure you post some images.

      MDW

      • Cutthroat Stalker (Scott C) Says:

        On the Wikipedia entry for sfumato, at the bottom, there was also the following two terms: Chiaroscuro and Tenebrism. Those kind of remind me of many of your pictures.

        Gee, learning about art is fun!

        -scott c

      • forestrat Says:

        I have consciously tried use chiaroscuro in my photographs. It is difficult when you have to take what light the world gives you rather than using studio lighting or paint.

        I do love Caravaggio’s work and I prefer solid black shadows so maybe I slipped over to the tenebrism by accident.

        MDW

  3. flandrumhill Says:

    I saw Caravaggio’s Beheading of John the Baptist a few years back in Malta. The canvas was enormous and so dark except for those light areas. His technique was so well rendered that it seemed beyond analysis. Mystery in art is good. As a viewer, if I understand the process in too much detail, some of the magic is lost.

    DaVinci’s use of sfumato is the ingredient that adds mystery to his portraits, such as the one of La Giaconda. Corners of the eyes and mouth are made foggy so that her emotional disposition is left to the imagination. I don’t know how you’d apply this technique in non-figurative photography.

    I greatly enjoyed reading your description of the photography process on your website. I agree with your decision to not alter photographs beyond the odd touch up as it is indeed quite misleading.

    • forestrat Says:

      Nothing like seeing the real thing. It is cool that the internet allows us to see images from all over the world that we may not have had a chance to otherwise, but nothing comes close to actually standing in front of a great art work.

      MDW

  4. Jonathan Says:

    Hi,

    Just came across when I was looking for pinhole info.

    Today I build my own pinhole on my digital camera, by mouting a brass plate on my lens mount, with a hole in it. I calculated the diameter of the hole, and the building method I used was 0,01mm accurate.
    It’s cool to see it working. :) But the results where not that good.

    What I was wondering about (and what you also noticed) is the sharpness. A pinhole photo -made with a digital camera- isn’t sharp.
    Howcome?
    An image made with an analogue looks way shaper.
    http://www.pinhole.cz/en/pinholecameras/l_001.html

    Maybe pinhole photo’s made with a digital camera are not that sharp as analogue, because of sensor construction?

    In my case the calculated diameter of the hole is 0.304 mm
    I’m pretty shure I’m spot on because the method I used making the hole.
    All the metal burrs are gone and the hole is perfectly round.

    The cause of unsharp images could be that the diameter isn’t correct.
    But, making new ones (slightly smaller/larger) isn’t helping, it just gets more out of focus.
    I’m at the sharperst point, which just isn’t that sharp.. (same sharpness as your picture above)

    What are your thoughts on this?

    • forestrat Says:

      I’m no expert on optics, but as I understand it the distance between the pinhole and the digital sensor is short so the hole has to be very small. When the hole gets very small it causes diffraction patterns that degrade the image.

      I guess sharpness just isn’t a feature of digital pinhole cameras. Building something that has a much greater distance to the film plain (like using an oatmeal box) and real film should be better.

      Maybe someday I’ll have time to to try it and I’ll report my findings.

      MDW

  5. Cletus Trinidad Says:

    Not all the digital pocket scale are produced equal nor they tend do the same position. I extremely recommend that you simply seek advice from a professional before purchasing one

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