Skip to main content

Lab #3 - Photopigments

Lab #3 - Photopigments

Our next task is to work out how you translate the image formed in the back of a pinhole camera into some kind of signal that your nervous system can work with. We'll start addressing this question by examining photopigments in Lab #3. To complete this lab, you'll need access to some sunprint paper, which is available from a variety of different sources. Here's where I bought mine: http://www.sunprints.org.

You can find the lab documents at the link below:

https://drive.google.com/file/d/17MVZqvyiCRdT_Qu5n_CtK3rVcUP0zoOG/view

When you're done, move on to the Lab #4 post to make a few more observations that will give us a little more information about the retina. Afterwards, we'll try to put all of this together into a more comprehensive description of what's happening at the back of the eye.


Comments

Popular posts from this blog

Monocular cues for depth perception

Monocular cues for depth perception In our last post, we discussed how you can use the information from your two eyes to estimate the relative depth of objects in the visual field. Both vergence and binocular disparity provided cues to where objects were situated in depth relative some fixation point, allowing us to obtain some information about the 3D arrangement of objects in space. Clearly, two eyes are helpful in resolving the ambiguity that follows from projecting the light coming from a three-dimensional scene onto a two-dimensional surface. We said that this projection of light onto the retina made it much harder to make good guesses about depth from one image, and that using two images was a necessary step towards making it possible for you to recover this information from the retinal data. However, consider the picture below:   Figure 1 - A boid in some trees. Some things here look closer to you than others, but how do you tell that when you don't have bino...

Observing the retina (and what it can do)

Observing the retina (and what it can do) Now that we’ve seen how images are formed inside of a pinhole camera, we have a sense of how patterns of light from the environment become patterns of light inside the eye. The next question is how those patterns become signals that can be sent from the eye to the brain. This process is called transduction , and within the eye, the structure that actually transduces light is called the retina . How does this bit of tissue sense light? Something must be happening that turns light into an electrical signal, but what? We’ll develop a quantitative model of how this works, but first, we’ll try to develop a basic understanding of the retina based on some simple observations. Compared to some of our previous discussions, this is going to be a little trickier – the retina is inside our eye, for example, so we can’t just look at the parts of it the way you were able to look at your own pupil. Instead, we’re going to adopt a dual strategy of (1) Makin...

What is Light?

What is light (and what does it do?) To begin talking about vision, we need to talk about light. What I mean is that we need to work out a way of thinking about what light is as a physical stimulus so that we can understand how it interacts with the physiology in our eye and brain. Our goal is to come up with a description of what light is that I’ll be calling a model . A good model allows us to account for some properties of a complex system and predict how it should behave under different circumstances. Good models also frequently leave out some aspects of a complex system in favor of being easier to work with, which means we have to remember that our descriptions of complex systems have limits. For now, we’ll have a limited set of phenomena that we’re trying to understand, but even so we’ll see that we’re leaving out some properties of light that are physically meaningful in some circumstances, but not terribly meaningful given our physiology. What is light?...