Good day nerds. So I've had a question on my mind for a while which is about what's the ideal length of an exposure? Can you get away with taking like 300 one second exposures and is that the same as taking one long 300 second exposure? And it's been on my mind for ages but I haven't actually done it so I thought I'd do it for you. I just took the same target at different exposure lengths which add up to the same amount. What's your intuition about this? My intuition is that the longer one is going to be the best quality. However when you stack multiple exposures you get rid of a lot of the noise so is there a nice sort of balance point in the middle there? Let's try it out. My name is Dylan and you're watching Star Stuff. I'm Knights with a Moon is Up or if there's not anything interesting that you're particularly fond of photographing it's a good time to fiddle. That means you can clean the observatory, you can do some planning, you can check your gear, you can try new things and try new gear and make sure it all works properly. So I'm going to do some fiddling. So the first thing I'm going to do is fix all that grease I want a tree in the spring I want a tree in the spring I want a tree in the spring Do you know what I'm like? Got a little helper today. What's your name? Jack, what are you doing? We're going on these colors we're doing the same for likes different colors So excuse the facial fungus, it is November. I'm useless at growing a beard, so this is the one month of the year that I get to look like a complete fool and everyone thinks I'm a good person. Let's have a break from sponsors in today's video. Today's video is just sponsored by getting the hell out of your comfort zone and just doing stuff with astronomy. I've been really busy lately with university and this new kitchen, which looks like a laboratory, which I really like, to be a good spot for doing science experiments with my kids. Here in Australia, is a super boring time in the sky. I mean, there's always stuff in the sky, but it's sort of the in-between season where Orion is up early in the morning and, God, I'm not going to get up that early. So I'll wait for Orion later. And all the good stuff is sitting in the West. I've got our second polar targets, like small Magellanic Cloud and a large Magellanic Cloud. Small Magellanic Cloud is sort of a disrupted galaxy. It's kind of not very photogenic. It's a very odd apparent size that have to mosaic it even with the raster 8. But for now, I thought I'd do this test on the Helix Nambia. So let's take a look. This is the first frame, which is 30 times 10 second exposures. Now I want you to forget about the vertical lines, because I wasn't there to ring in this. I didn't want to waste time did the ring between these exposures. And also my stars are a little bit elongated because it was really windy last night. However, you can see that we have a little bit of detail, but not a lot. The Helix Nambia has a brow feature across the top of it. And this isn't really showing up very clearly in this image. Even though the total integration time is the full 300 seconds, and even though I'm using the raster with an F2 focal ratio, it's still not pulling out that data. In this case, having all of that total integration time is no substitute for the full long exposure. So it's still valuable and it's still a good way to get a target, especially quickly. There are some advantages in using short exposures. Of course, more of them are going to be usable. If you're tracking only for 10 seconds, it's going to be easy to get those round stars. And you'll have more exposures that you can keep, rather than, say, if you're doing a full five minute exposure, and you get a little bit of wind, and then that whole five minute exposure is ruined, and you've got to throw it out. So there can be some advantages in that fast shooting method. However, let's have a look at the next one. Now you can see we're getting much more of that brow detail. We've stacked these 10 images, so we have reduced a fair bit of the noise, but it's still a pretty noisy image. So you would need way more of these to get that return on investment. And I can tell you now this shot is closer to the full single five minute frame, which I'll show you in a second. But this is still a good middle ground between a really short exposure and the super long exposures. I was able to get a lot of these. When you're taking a number of images to stack, I find that the nice point is around 30 to 40. So if you're shooting with the CCD camera, about 30 frames minimum, before you start getting a signal to noise ratio, that doesn't get much better with the more frames that you add. If you're shooting with the ZWO or other 12-bit cameras, then you do need a little more. So I would go to minimum 40 exposures for that same return investment for the signal to noise ratio. But let's have a look at the single five minute exposure. And I'll put this side by side in a second, but you can see that the level of detail and the brow is still there. It's actually not far off the 30 second exposures. This one's a lot cleaner, and the noise profile is a lot lower. You can see that there's a better signal to noise ratio, straight off the bat, even without having to stack a single image. So if you can go for those longer exposures, and you've got time to shoot a five minute exposure or longer, you are going to get a better signal. It's going to be a much better image at the end. There isn't that much of a difference between the brightness level between these two. It's just the noise level. So if you got more of these exposures, you could make an image that is, visually, not far off doing these long five minute exposures. And you could save yourself literally hours of integration time. That said, if we put them side by side, the difference is clear. So if you can afford the time to get those five minute exposures, definitely go ahead and do that. But it is a diminishing return on investment. I'm pretty lazy, and I do tend to shoot 30 second or one minute or two minute exposures with the rassa instead of the four five minute ones. And it means I've got more usable frames, especially if the wind comes and shakes the scope, but I have to throw out a whole five minute exposure. It just makes it quicker to get that data. So there is a myth in astrophotography that you can get away with doing smaller subs and you'll get the equivalent result in the end. And that's not true. Really faint magnitude stuff isn't going to come out with those shorter exposures. You are not pulling in more signal simply by stacking more shorter exposures. So where possible, you really do need to put in the time with longer exposures, especially to draw out the faint stuff. There is a little bit more detail as well. You can see if I'm really zooming close. There is just a little bit more finer detail in the clouds and the nebulosity there as well. So you could probably resolve more of that deep towel with more of those shorter stacks, but you don't get the brightness and the luminosity. And that will never be recovered from doing shorter exposures stat. So I encourage you to do these sorts of experiments with your gear and try out new things. That's about it for me. I'm not going to do a bunch of test the videos, but I am enjoying my new Tesla and especially the autopilot stuff and autonomy in general. Here's some videos of the car driving and parking itself, which I think is amazing. So if you want to buy a Tesla, I'll leave my referral link down below. In terms of other news in the astronomy world at the moment, we are looking at Comet Borosol, the interstellar comet, which is approaching and should be visible in the Southern hemisphere around December. So I will be on the lookout for that. It's not a particularly phogenic object. It's going to be small. However, this is a very unique object. So we'll be in tune to see if we can get any kind of color information and observe this as it gets closer to Perihelian. What else has been happening? I have finished my astronomy degree apart from a couple of little submissions I have to do. I've got four weeks left of my astronomy degree, so I can maybe, if I graduate, actually drop the term amateur astronomer and just be an astronomer. But we're all astronomers. You don't need a degree for that. But for now, you know what's coming. It seems to upset a great many people who watch my videos. And that is, if it is meaningless, we're all going to die.