Angles of Incidence and Reflection

Learn how to position your lights right every time.

If you’ve ever struggled to position a light correctly, or wondered how to avoid glaring reflections in an image, this class will answer all of your questions.

Here, Karl breaks down some simple laws of physics to help you get to grips with how reflections work and how you can optimise them in your photography.

After describing the four different types of reflection, Karl goes on to explain the angle of incidence and the angle of reflection. (In the video, the latter is sometimes referred to as the ‘angle of reflectance’.)

Understanding how these angles relate to one another is crucial to capturing successful photographs. Using graphical examples, mirrors, laser pointers, smoke pellets and even a Harley Davidson motorcycle, Karl demonstrates how to put this key aspect of lighting theory into practice.

To wrap up the class, he shares a handy technique for removing glaring reflections from a shot – without having to move your lights.

By the end of the video, you’ll have a deeper understanding of how light works and how to harness and manipulate it for stronger images.

In this photography class:

  • The four types of reflection
  • The angle of incidence
  • The angle of reflection
  • Using polarising filters in photography
  • How to use a laser pointer to position studio lights
  • Adjusting focal length to alter reflections

If you enjoyed this class, check out Understanding Light or Harley Davidson Night Rod Photoshoot.

You may also like to watch How and Why to Polarise Light in Studio Photography, which Karl mentions in the conclusion to this class.

Questions? Please post them in the comments below.

Comments

  5. ppgoesbig

    Hello! Amazing class. The focal length vs reflection area point blew my mind.

    This is a bit off topic, but I can’t get over it. Regarding the tiles – to me it would seem much easier to shoot them lying on a flat surface rather than go through the hassle of mounting them on a wall. Was there a benefit to shooting them vertically other than it being more clearly viewable for the video? Thank you!

    1. Hi and thank you. Mostly so the lesson was more clear in the video. The other advantage is not having to climb up a ladder to look through the camera or adjust the position of your lights.

  8. Hello Karl,

    It’s me again. For product photography, we often use more than one light. How do we set up different lightings correctly when the camera is only pointing at one position on the product but we have 3 or 4 lights set up at different locations? How do we calculate the angle of incidence and reflection?

    1. Hi, you test each one individually. But remember you should only be adding more lights for a specific reason. Some product shots are done with just one light, each light has to have a purpose and reason for it to be there.

  9. This is the best video I have ever watched on this subject. The illustrations and actual live shooting were very helpful in explaining something that is very difficult for a lot of people who don’t understand the physics. Thank you Karl.

  10. Hello Karl,
    watching this a couple of times truly shed more light on angles of incidence/reflectance concepts, no pun intended. I have a question though regarding the last part of this class which is the focal length and positioning of the camera/focal plane in relation to the angle of incidence of the light. My first query would be as it follows:

    Do we change the focal length as a consequence of moving the camera so that narrowing the angle of view allows filling the frame and achieve the same results in terms of perspective or is it the focal length in itself that allows avoiding the unwanted glare? I mean let us say that we do not care about filling the frame therefore changing the focal length of the lens… Would moving the camera further away from the subject alone without changing the lens suffice to kill the glare on the subject surface?

    Also, would the use of a tilt/shift lens aid in this scenario so that no repositioning of the camera focal plane were necessary to achieve the same results?

    Thank you so much.

    1. Hi Thanks and I’m glad you enjoyed the class. Yes we change the focal length because the camera has been moved further back, we do this to make sure the subject still fills the frame and in increasing the focal length we reduce the angle of the family of angles. Moving the camera further away alone but without changing the focal length will actually make it worse as the area of the family of angles actually increases. Cheers Karl.

  12. castlewolfpictures

    Karl, beautiful breakdown of angles of reflectance and I believe it fully gave an answer to my confusion of light height placement. In the scenario of your motorbike shot, the light you diffused by bouncing off your infinity wall – it could have also been shot through a giant scrim or a massive octa/box? I must ask as well did you have the foresight to know you wanted to bounce the gas tank light off a wall like that and that is why you chose that exact spot in your studio? Incredible either way. It seems as if you have to treat every angular surface of a product as needing its own light source. The example in my head would be shooting a car head on you may need separate light sources for the hood, roof, sides and very front headlight area.

    1. Hi, thanks. Yes I often know where the light needs to go just from experience and looking at the angle and imagining where it would end up. I only use the laser if I need to check precisely. For what you mention on a car front on we have a class that covers exactly what you describe in our automotive section.

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