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MinutePhysics Briefly Explains How Pinholes and Apertures Work

By Justin Heyes on November 15th 2014

Without understanding the principles of light and how they correlate to small apertures, pinhole cameras can seem almost like magic in the way they capture a relatively sharp image without a lens. Even with a lens you need an adjustable aperture in order to control depth of field. In the short video by MinutePhysics, they briefly explain how pinholes, lenses and apertures work.

How to See Without Glasses

In How to See Without Glasses, Henry Reich demonstrates a technique making a pinhole with your fingers to see at greater distances; the same way we stop down a lens to increase the depth of field. Lenses like the ones on our cameras and in our eyes can only focus light at a particular distance away – any further, they get blurred and create that much loved bokeh.


[REWIND:Here’s What Your Camera Does When You Change ISO & Why Higher ISO Creates Noise]

Unlike lenses, pinholes use the reduction of light to focus instead of relying on optics. The reduction of light causes light to focus at one particular point from any distance. This is what happens when we close down the aperture in our lens; we prevent the stray points of light from defocusing our images.


What the video fails to mention is that at a certain threshold, reducing the aperture can help create tack sharp images; move past that threshold and you enter in the world of defraction. Light, being the wave that it is, will bend and spread around the edge of an object causing banding and spectrum change. What that means for us photographers is that it will make our once sharp image blurry.


If you leave your lens fully open all the time, you will get very shallow depth of field, but sacrifice sharpness. For maximum sharpness, it is recommended to stop your lens. Anything between f/4 and f/8 will create sharp images. Smaller apertures below f/22 for full frame and f/16 for APS-C will cause light to defract and make your images soft.

[Via MinutePhysics Youtube / Image screen captures]

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Justin Heyes wants to live in a world where we have near misses and absolute hits; great love and small disasters. Starting his career as a gaffer, he has done work for QVC and The Rachel Ray Show, but quickly fell in love with photography. When he’s not building arcade machines, you can find him at local flea markets or attending car shows.

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Website: Justin Heyes
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Q&A Discussions

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  1. David Hall

    I can’t tell you how many times I’ve created a small pin hole with my hand to read something when I’ve lost my glasses. Too funny.

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  2. Stan Rogers

    The diffraction thing is likely just trying to avoid lying to people (like, for instance, saying that light is waves). There’s only so much you can get across in a fun little video like this, and trying to simplify things to fit just ends up giving people the wrong idea — and would likely result in different videos giving apparently contradictory information. Diffraction of light is kind of cool, but it doesn’t quite work like diffraction of waves — although the wave model is “good enough” for an intuitive understanding, it would need to come with a big flashing disclaimer so that anything that has to mention photons in the series can, without putting the user into that awkward duality mental state that physicists were struggling with at the beginning of the Twentieth.

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  3. Kim Farrelly

    Love minute physics as do my kids who think the narrator sounds like Jesse Eisenberg (Blue from Rio)

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  4. Nick Viton

    True story; when I was in high school I couldn’t see the blackboard very well, so I did the pinhole-with-my-fingers trick all the time in order to see what the teacher was writing on the board. One teacher finally suggested I get my eyes checked and sure enough I needed glasses. …I was a little slow on the uptake with that one.

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  5. Lex Arias


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  6. Brandon Dewey

    Great Video. The little circle thing does really works.

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