G'day, Dillon O'Donnell here from the Boreen Bay Observatory. Are diffraction spikes lame? Yes, yes they are. Before you click off this video and discuss because you've dropped your life savings on a 14-inch rich-christin telescope, let me explain my position. You might think you don't like my position, but what you actually don't like is the sound of my voice. I know my delivery is not for everyone, but it is 2023. And I think we can both sit down and have a civil discussion, a social intercourse, and we can exchange ideas. I can outline my thoughts, do some experiments, and show you why your opinion is wrong and dumb. My name is Dillon O'Donnell and you're watching Star Star. Let me tell you a story. When I started out in astrophotography and I took my first crappy photos of the Orion Nambilla using my little four-inch mid-Casagrange telescope, I saw the images that came down and I immediately thought, where are the spikes? I want my images to look like a magazine. This doesn't look like a magazine at all. Magazines have spikes. I fully expected those spikes to be there and I was disappointed when they weren't. I did some googling and realized that the Schmidt-Casagrange telescope design doesn't actually have diffraction spikes. I was never gonna get these pretty spikes and I was honestly pretty disappointed. But after a while I dug in and I thought, no. My little four-inch Schmidt-Casagrange is right. It's all the other astrophotographers who are wrong. In a moment I'm going to explain diffraction spikes and also how we can make them on our own telescopes in case you feel like you're missing out. But for now, let me thank these show sponsors high point scientific. High point scientific are new, your base telescope vendor and they'll sell you everything you need for astrophoreotography. You can replicate my rig using the links down in the description where you can build your own stuff and have pretty diffraction spikes. It's really up to you. They're not gonna push you in any particular brand or any particular direction. They just wanna help you with your astrophotography and they have a price-managed guarantee. So www.highpoint-side-divic.com. So I get it. Diffractions spikes are pretty. They're pretty in a kind of Barbie unicorn rainbow sparkles kind of way. And if you ask any astrophotographer, most of them will say that they like the diffraction spikes particularly on star clusters and star-rich images. Diffraction spikes are caused by an optical effect that occurs when light is bounced off an obstruction. Because light is a particle but it propagates like a wave or something. I don't know, but I can't affirm the effect is real. So here's a little obstruction, just a piece of wire. Now we would expect when we put it into the path of light, it should cause a shadow, right? It should cause like a shadow like this. But when we do that, this is what happens. It's perpendicular spike. If we go horizontal, we get a vertical spike. We end right? Chris Patterson has a pretty good explanation of what causes the spikes on the James Webb space telescope. And counterintuitively, it's the gaps between the mirror that add up to the six bike star shape, not the three struts, which is what my intuition told me it was. The struts on the James Webb space telescope cause a secondary minor diffraction spike also with six spikes. Hubble has a cross beams structure, so it has four spikes. If you have a Schmidt-Cassegrained telescope like mine, there are no struts, so there are no spikes. The classic refractive design doesn't have any struts either, so there are no spikes on those telescopes also. Stars appear round, not spiky. Quick refresher, stars are actually round, not spiky. The star is real, the spikes are not. The problem with traditional refractive telescopes is that there is a size limit, so you can't make them super big, or they'll break and burn away. With a reflecting telescope, you can design the scope to be much, much bigger. But even those of us on team reflecti have a similar problem. In a classic Schmidt-Cassegrained design, we can float the mirror in the glass. No struts, no spikes in your stars. Just the way you got intended. But if you make the telescope big enough, at some point you're gonna need struts to hold that mirror in place. That's why big observatories typically have diffraction spikes on their images, they have big telescopes and they need struts to hold that secondary mirror. But stars in art and history have always had spikes. We've always as humans drawn the stars with spikes. And this is before we had telescopes or struts in those telescopes. So what's going on here? The answer is pretty simple. It comes down to the fact that our eyes are stupid. I've been saying this for a while now, but let me show you what I mean. Here's a picture of my eye. Do you notice anything? See all those blood vessels and other things in my retina? All of these build up occlusions for the light, even the eyelashes. In fact, there's an experiment you can do right now. Grab your phone and turn the flashlight on and look at the difference between squinting and opening your eyes so the eyelashes are out of the way. Do you see the spikes? You can even change the diffraction spike on the sun. See the spike here? Just by having a dirty lens, it's now if I swipe vertically, we should get a horizontal spike. Over the lens. Magic, horizontal spike. Change it back to your vertical. BELL RINGS I am God. And the fact is no two eyeballs are the same. We all have different retinal blood vessel patterns and different eyelashes. So the diffraction spikes that you see in your eyes when you look at a distant star or a street light or something like that are different to the diffraction spikes that everybody else sees. It's kind of weird when you think about it. It's like we're all individually delusional. Real professional astronomers though realize that the diffraction spikes are a trade-off. They are a bug and not a feature. They are a necessary evil if you want the kind of focal length it takes to do real science in deep space. That hasn't stopped researchers from trying to get rid of them though. When finished, the giant Magellan telescope will be the largest, most powerful telescope on earth. And it's designed as a trying to get rid of diffraction spikes. The circular mirrors go some way to reducing the diffraction spikes by avoiding hard, straight lines that multiply the effect. Like what's happening with the James Webb. The real innovation are the spider arms, which look really crooked and weird, but they're intentionally misaligned to slip into the mirror gaps and get rid of the diffraction spikes. Or at least that's the theory anyway. Hopefully when this telescope goes live, we can see how well we've done. A lot of astronomers complain about starlink ruining exposures. But if you're going to complain about artificial obstructions throwing light around one of your exposures, we have to complain about artificial obstructions throwing light around all your exposures. I wonder if we've missed anything because it was hidden right here. Anyway, that's an experiment. It's time to prove my point and make the Dylan from eight years ago happy and give him some diffraction spikes. Now, I wasn't gonna spend any money on such a foolish endeavor or 3D print something fancy like the classicists will. I use some of my kids' play dough and some sticks from the garden and some painters' tapes so I don't leave any sticky substances on my big tube. Behold, the James Webb Space Telescope we have at home. And then I tested it out on a globular cluster. I could see the spikes, but they weren't very obvious. So I tried something brighter. Tollamy's cluster. This looked pretty good with some clear spikes, but the nearly full moon and possibly my kitchen light were seriously screwing up my backgrounds. I decided to hit a named star away from the moon. Named stars are bright and easy to image with short exposures. I pointed my telescope at the sky for 20 seconds. And this is what I saw. Well, there it is. I kinda wanted to hate this photo and I was supposed to do a video about proving the point that diffraction spikes actually suck. But I'm not gonna lie, that's pretty dope. You'll notice the diffraction spikes that there's a kind of rainbow equality in them. That's because the wavelength of light causes spikes at different intervals. So you can see this if I think the image. You know, that's it for me. In conclusion, I guess it's that diffraction spikes. Go on, say it. Pretty. Nada. My name is Dylan O'Donnell. You're watching Star Stuff. Remember, everything is meaningless. We're all going to die.